Honors & Awards

  • Life Sciences Research Foundation Postdoctoral Fellowship, Merck Research Laboratories (2019-2022)
  • Dean's Postdoctoral Fellowship, Stanford School of Medicine (2019)
  • Graduate Student Gold Award, Materials Research Society (2017)
  • O.P. Jindal Engineering and Management Scholarship, O.P. Jindal Group (2010)

Professional Education

  • Doctor of Philosophy, Washington University (2017)
  • Bachelor of Technology, National Institute of Technology (2012)

Stanford Advisors


All Publications

  • Metal-Organic Framework Encapsulation for the Preservation and Photothermal Enhancement of Enzyme Activity SMALL Tadepalli, S., Yim, J., Cao, S., Wang, Z., Naik, R. R., Singamaneni, S. 2018; 14 (7)
  • Gold Nanorod-Mediated Photothermal Enhancement of the Biocatalytic Activity of a Polymer-Encapsulated Enzyme CHEMISTRY OF MATERIALS Tadepalli, S., Yim, J., Madireddi, K., Luang, J., Naik, R. R., Singamaneni, S. 2017; 29 (15): 6308–14
  • Bio-Optics and Bio-Inspired Optical Materials. Chemical reviews Tadepalli, S. n., Slocik, J. M., Gupta, M. K., Naik, R. R., Singamaneni, S. n. 2017; 117 (20): 12705–63


    Through the use of the limited materials palette, optimally designed micro- and nanostructures, and tightly regulated processes, nature demonstrates exquisite control of light-matter interactions at various length scales. In fact, control of light-matter interactions is an important element in the evolutionary arms race and has led to highly engineered optical materials and systems. In this review, we present a detailed summary of various optical effects found in nature with a particular emphasis on the materials and optical design aspects responsible for their optical functionality. Using several representative examples, we discuss various optical phenomena, including absorption and transparency, diffraction, interference, reflection and antireflection, scattering, light harvesting, wave guiding and lensing, camouflage, and bioluminescence, that are responsible for the unique optical properties of materials and structures found in nature and biology. Great strides in understanding the design principles adapted by nature have led to a tremendous progress in realizing biomimetic and bioinspired optical materials and photonic devices. We discuss the various micro- and nanofabrication techniques that have been employed for realizing advanced biomimetic optical structures.

    View details for PubMedID 28937748

  • Influence of Surface Charge of the Nanostructures on the Biocatalytic Activity. Langmuir : the ACS journal of surfaces and colloids Tadepalli, S. n., Wang, Z. n., Liu, K. K., Jiang, Q. n., Slocik, J. n., Naik, R. R., Singamaneni, S. n. 2017; 33 (26): 6611–19


    The physicochemical properties of abiotic nanostructures determine the structure and function of biological counterparts in biotic-abiotic nanohybrids. A comprehensive understanding of the interfacial interactions and the predictive capability of their structure and function is paramount for virtually all fields of bionanotechnology. In this study, using plasmonic nanostructures as a model abiotic system, we investigate the effect of the surface charge of nanostructures on the biocatalytic reaction kinetics of a bound enzyme. We found that the surface charge of nanostructures profoundly influences the structure, orientation, and activity of the bound enzyme. Furthermore, the interactions of the enzyme with nanoparticles result in stable conjugates that retain their functionality at elevated temperatures, unlike their free counterparts that lose their secondary structure and biocatalytic activity.

    View details for PubMedID 28605903

  • Effect of size and curvature on the enzyme activity of bionanoconjugates. Nanoscale Tadepalli, S. n., Wang, Z. n., Slocik, J. n., Naik, R. R., Singamaneni, S. n. 2017; 9 (40): 15666–72


    Biotic-abiotic hybrids comprised of globular proteins and functional nanostructures with complementary and synergistic properties are central to a number of bionanotechnological applications. A comprehensive understanding of the effect of physicochemical properties of abiotic nanostructures on the biological activity of the bionanoconjugates is critical in the design of these bio-nano hybrids. In this study, using size and curvature-controlled gold nanoparticles as a model abiotic system, we investigated the effect of hydrodynamic diameter and surface curvature on the activity of a model enzyme, horseradish peroxidase (HRP), adsorbed on the surface of the nanostructures. In contrast with the previous studies, we have employed a novel class of gold superstructures (gold nanoparticles on spheres) to deconvolute the effects of size and curvature on the catalytic activity of the bionanoconjugates. This study improves our understanding of the bio/nano interface and the design of bioinorganic hybrids with potential applications in biomimetic and bioenabled sensors, energy harvesting, optoelectronic components and devices, responsive and autonomous materials.

    View details for PubMedID 28993826

  • Adsorption Behavior of Silk Fibroin on Amphiphilic Graphene Oxide ACS BIOMATERIALS SCIENCE & ENGINEERING Tadepalli, S., Hamper, H., Park, S. H., Cao, S., Naik, R. R., Singamaneni, S. 2016; 2 (7): 1084-1092
  • Adsorption Behavior of Silk Fibroin on Amphiphilic Graphene Oxide. ACS biomaterials science & engineering Tadepalli, S. n., Hamper, H. n., Park, S. H., Cao, S. n., Naik, R. R., Singamaneni, S. n. 2016; 2 (7): 1084–92


    Graphene oxide-silk composites have gained a significant interest in the recent times because of the unique mechanical properties of both GO and silk and their ability to form layered structures that exhibit a striking resemblance to the layered (brick-mortar) composites found in nature. However, various aspects of the interaction between silk and graphene oxide (e.g., conformation and distribution of the silk chains on chemically heterogeneous GO surface) are not completely understood. In this study, we demonstrate that the interaction between the silk fibroin chains and GO can be modulated by altering the pH of the silk fibroin solution. We employed atomic force microscopy (AFM) and Fourier transform infrared (FTIR) spectroscopy to probe the distribution and the secondary structure of silk fibroin adsorbed on GO. In acidic pH conditions (i.e., pH < pI), a high density of silk chains were found to adsorb on the GO surface, whereas an increase in pH resulted in a progressive decrease in the density of the adsorbed silk chains. This pH-dependent adsorption is ascribed to the electrostatic interactions between the negatively charged GO surface and the tunable ionization of the silk molecules. The secondary structure of silk fibroin chains adsorbed on GO was also found to be highly dependent on the pH. This study provides a deeper understanding of the interaction between GO and silk fibroin that is critical for the design and fabrication of bioinspired nanocomposites with tailored mechanical properties.

    View details for DOI 10.1021/acsbiomaterials.6b00232

    View details for PubMedID 33445236

  • Peptide Functionalized Gold Nanorods for the Sensitive Detection of a Cardiac Biomarker Using Plasmonic Paper Devices SCIENTIFIC REPORTS Tadepalli, S., Kuang, Z., Jiang, Q., Liu, K., Fisher, M. A., Morrissey, J. J., Kharasch, E. D., Slocik, J. M., Naik, R. R., Singamaneni, S. 2015; 5


    The sensitivity of localized surface plasmon resonance (LSPR) of metal nanostructures to adsorbates lends itself to a powerful class of label-free biosensors. Optical properties of plasmonic nanostructures are dependent on the geometrical features and the local dielectric environment. The exponential decay of the sensitivity from the surface of the plasmonic nanotransducer calls for the careful consideration in its design with particular attention to the size of the recognition and analyte layers. In this study, we demonstrate that short peptides as biorecognition elements (BRE) compared to larger antibodies as target capture agents offer several advantages. Using a bioplasmonic paper device (BPD), we demonstrate the selective and sensitive detection of the cardiac biomarker troponin I (cTnI). The smaller sized peptide provides higher sensitivity and a lower detection limit using a BPD. Furthermore, the excellent shelf-life and thermal stability of peptide-based LSPR sensors, which precludes the need for special storage conditions, makes it ideal for use in resource-limited settings.

    View details for DOI 10.1038/srep16206

    View details for Web of Science ID 000364446200002

    View details for PubMedID 26552720

    View details for PubMedCentralID PMC4639779

  • Shape-Dependent Biodistribution of Biocompatible Silk Microcapsules. ACS applied materials & interfaces Cao, S., Tang, R., Sudlow, G., Wang, Z., Liu, K., Luan, J., Tadepalli, S., Seth, A., Achilefu, S., Singamaneni, S. 2019


    Microcapsules are emerging as promising microsize drug carriers due to their remarkable deformability. Shape plays a dominant role in determining their vascular transportation. Herein, we explored the effect of the shape of the microcapsules on the in vivo biodistribution for rational design of microcapsules to achieve optimized targeting efficiency. Silk fibroin, a biocompatible, biodegradable, and abundant material, was utilized as a building block to construct biconcave discoidal and spherical microcapsules with diameter of 1.8 mum and wall thickness of 20 nm. We have compared the cytocompatibility, cellular uptake, and biodistribution of both microcapsules. Both biconcave and spherical microcapsules exhibited excellent cytocompatibility and internalization into cancer cells. During blood circulation in mice, both microcapsules showed retention in liver and kidney and most underwent renal clearance. However, we observed significantly higher accumulation of biconcave silk microcapsules in lung compared with spherical microcapsules, and the accumulation was found to be stable in lung even after 3 days. The higher concentration of biconcave discoidal microcapsules found in lung arises from pulmonary environment, margination dynamics, and enhanced deformation in bloodstream. Red blood cell (RBC)-mimicking silk microcapsules demonstrated here can potentially serve as a promising platform for delivering drugs for lung diseases.

    View details for PubMedID 30640448

  • Photothermally Active Reduced Graphene Oxide/Bacterial Nanocellulose Composites as Biofouling-Resistant Ultrafiltration Membranes ENVIRONMENTAL SCIENCE & TECHNOLOGY Jiang, Q., Ghim, D., Cao, S., Tadepalli, S., Liu, K., Kwon, H., Luan, J., Min, Y., Jun, Y., Singamaneni, S. 2019; 53 (1): 412–21


    Biofouling poses one of the most serious challenges to membrane technologies by severely decreasing water flux and driving up operational costs. Here, we introduce a novel anti-biofouling ultrafiltration membrane based on reduced graphene oxide (RGO) and bacterial nanocellulose (BNC), which incoporates GO flakes into BNC in situ during its growth. In contrast to previously reported GO-based membranes for water treatment, the RGO/BNC membrane exhibited excellent aqueous stability under environmentally relevant pH conditions, vigorous mechanical agitation/sonication, and even high pressure. Importantly, due to its excellent photothermal property, under light illumination, the membrane exhibited effective bactericidal activity, obviating the need for any treatment of the feedwater or external energy. The novel design and in situ incorporation of the membranes developed in this study present a proof-of-concept for realizing new, highly efficient, and environmental-friendly anti-biofouling membranes for water purification.

    View details for PubMedID 30215517

  • Aqueous toughening in crosslinked marine animal proteins Grant, A., Krecker, M., Tadepalli, S., Gupta, M., Crosby, M., Dennis, P., Singamaneni, S., Naik, R., Tsukruk, V. AMER CHEMICAL SOC. 2018
  • Metal-Organic Framework Encapsulation for Biospecimen Preservation CHEMISTRY OF MATERIALS Wang, C., Sun, H., Luan, J., Jiang, Q., Tadepalli, S., Morrissey, J. J., Kharasch, E. D., Singamaneni, S. 2018; 30 (4): 1291–1300
  • Metal-Organic Framework Encapsulation for the Preservation and Photothermal Enhancement of Enzyme Activity. Small (Weinheim an der Bergstrasse, Germany) Tadepalli, S. n., Yim, J. n., Cao, S. n., Wang, Z. n., Naik, R. R., Singamaneni, S. n. 2018


    Interfacing biomolecules with functional materials is a key strategy toward achieving externally-triggered biological function. The rational integration of functional proteins, such as enzymes, with plasmonic nanostructures that exhibit unique optical properties such as photothermal effect provides a means to externally control the enzyme activity. However, due to the labile nature of enzymes, the photothermal effect of plasmonic nanostructures is mostly utilized for the enhancement of the biocatalytic activity of thermophilic enzymes. In order to extend and utilize the photothermal effect to a broader class of enzymes, a means to stabilize the immobilized active protein is essential. Inspired by biomineralization for the encapsulation of soft tissue within protective exteriors in nature, metal-organic framework is utilized to stabilize the enzyme. This strategy provides an effective route to enhance and externally modulate the biocatalytic activity of enzymes bound to functional nanostructures over a broad range of operating environments that are otherwise hostile to the biomolecules.

    View details for PubMedID 29323458

  • Advancing Peptide-Based Biorecognition Elements for Biosensors Using in-Silico Evolution. ACS sensors Xiao, X. n., Kuang, Z. n., Slocik, J. M., Tadepalli, S. n., Brothers, M. n., Kim, S. n., Mirau, P. A., Butkus, C. n., Farmer, B. L., Singamaneni, S. n., Hall, C. K., Naik, R. R. 2018; 3 (5): 1024–31


    Sensors for human health and performance monitoring require biological recognition elements (BREs) at device interfaces for the detection of key molecular biomarkers that are measurable biological state indicators. BREs, including peptides, antibodies, and nucleic acids, bind to biomarkers in the vicinity of the sensor surface to create a signal proportional to the biomarker concentration. The discovery of BREs with the required sensitivity and selectivity to bind biomarkers at low concentrations remains a fundamental challenge. In this study, we describe an in-silico approach to evolve higher sensitivity peptide-based BREs for the detection of cardiac event marker protein troponin I (cTnI) from a previously identified BRE as the parental affinity peptide. The P2 affinity peptide, evolved using our in-silico method, was found to have ∼16-fold higher affinity compared to the parent BRE and ∼10 fM (0.23 pg/mL) limit of detection. The approach described here can be applied towards designing BREs for other biomarkers for human health monitoring.

    View details for PubMedID 29741092

  • Catalytically Active Bacterial Nanocellulose-Based Ultrafiltration Membrane. Small (Weinheim an der Bergstrasse, Germany) Xu, T. n., Jiang, Q. n., Ghim, D. n., Liu, K. K., Sun, H. n., Derami, H. G., Wang, Z. n., Tadepalli, S. n., Jun, Y. S., Zhang, Q. n., Singamaneni, S. n. 2018


    Large quantities of highly toxic organic dyes in industrial wastewater is a persistent challenge in wastewater treatment processes. Here, for highly efficient wastewater treatment, a novel membrane based on bacterial nanocellulose (BNC) loaded with graphene oxide (GO) and palladium (Pd) nanoparticles is demonstrated. This Pd/GO/BNC membrane is realized through the in situ incorporation of GO flakes into BNC matrix during its growth followed by the in situ formation of palladium nanoparticles. The Pd/GO/BNC membrane exhibits highly efficient methylene orange (MO) degradation during filtration (up to 99.3% over a wide range of MO concentrations, pH, and multiple cycles of reuse). Multiple contaminants (a cocktail of 4-nitrophenol, methylene blue, and rhodamine 6G) can also be effectively treated by Pd/GO/BNC membrane simultaneously during filtration. Furthermore, the Pd/GO/BNC membrane demonstrates stable flux (33.1 L m-2h-1) under 58 psi over long duration. The novel and robust membrane demonstrated here is highly scalable and holds a great promise for wastewater treatment.

    View details for PubMedID 29516638

  • Extreme Mechanical Behavior of Nacre-Mimetic Graphene-Oxide and Silk Nanocomposites. Nano letters Xie, W. n., Tadepalli, S. n., Park, S. H., Kazemi-Moridani, A. n., Jiang, Q. n., Singamaneni, S. n., Lee, J. H. 2018


    Biological materials have the ability to withstand extreme mechanical forces due to their unique multilevel hierarchical structure. Here, we fabricated a nacre-mimetic nanocomposite comprised of silk fibroin and graphene oxide that exhibits hybridized dynamic responses arising from alternating high-contrast mechanical properties of the components at the nanoscale. Dynamic mechanical behavior of these nanocomposites is assessed through a microscale ballistic characterization using a 7.6 μm diameter silica sphere moving at a speed of approximately 400 m/s. The volume fraction of graphene oxide in these composites is systematically varied from 0 to 32 vol % to quantify the dynamic effects correlating with the structural morphologies of the graphene oxide flakes. Specific penetration energy of the films rapidly increases as the distribution of graphene oxide flakes evolves from noninteracting, isolated sheets to a partially overlapping continuous sheet. The specific penetration energy of the nanocomposite at the highest graphene oxide content tested here is found to be significantly higher than that of Kevlar fabrics and close to that of pure multilayer graphene. This study evidently demonstrates that the morphologies of nanoscale constituents and their interactions are critical to realize scalable high-performance nanocomposites using typical nanomaterial constituents having finite dimensions.

    View details for PubMedID 29314859

  • Ultrarobust Biochips with Metal-Organic Framework Coating for Point-of-Care Diagnosis. ACS sensors Wang, C. n., Wang, L. n., Tadepalli, S. n., Morrissey, J. J., Kharasch, E. D., Naik, R. R., Singamaneni, S. n. 2018


    Most biosensors relying on antibodies as recognition elements fail in harsh environment conditions such as elevated temperatures, organic solvents, or proteases because of antibody denaturation, and require strict storage conditions with defined shelf life, thus limiting their applications in point-of-care and resource-limited settings. Here, a metal-organic framework (MOF) encapsulation is utilized to preserve the biofunctionality of antibodies conjugated to nanotransducers. This study investigates several parameters of MOF coating (including growth time, surface morphology, thickness, and precursor concentrations) that determine the preservation efficacy against different protein denaturing conditions in both dry and wet environments. A plasmonic biosensor based on gold nanorods as the nanotransducers is employed as a model biodiagnostic platform. The preservation efficacy attained through MOF encapsulation is compared to two other commonly employed materials (sucrose and silk fibroin). The results show that MOF coating outperforms sucrose and silk fibroin coatings under several harsh conditions including high temperature (80 °C), dimethylformamide, and protease solution, owing to complete encapsulation, stability in wet environment and ease of removal at point-of-use by the MOF. We believe this study will broaden the applicability of this universal approach for preserving different types of on-chip biodiagnostic reagents and biosensors/bioassays, thus extending the benefits of advanced diagnostic technologies in resource-limited settings.

    View details for PubMedID 29336151

  • An in situ grown bacterial nanocellulose/graphene oxide composite for flexible supercapacitors JOURNAL OF MATERIALS CHEMISTRY A Jiang, Q., Kacica, C., Soundappan, T., Liu, K., Tadepalli, S., Biswas, P., Singamaneni, S. 2017; 5 (27): 13976–82

    View details for DOI 10.1039/c7ta03824k

    View details for Web of Science ID 000405190000009

  • Amplification of Refractometric Biosensor Response through Biomineralization of Metal-Organic Framework Nanocrystals ADVANCED MATERIALS TECHNOLOGIES Luan, J., Hu, R., Tadepalli, S., Morrissey, J. J., Kharasch, E. D., Singamaneni, S. 2017; 2 (7)
  • Wood Graphene Oxide Composite for Highly Efficient Solar Steam Generation and Desalination ACS APPLIED MATERIALS & INTERFACES Liu, K., Jiang, Q., Tadepallifit, S., Raliya, R., Biswas, P., Naik, R. R., Singamaneni, S. 2017; 9 (8): 7675-7681


    Solar steam generation is a highly promising technology for harvesting solar energy, desalination and water purification. We introduce a novel bilayered structure composed of wood and graphene oxide (GO) for highly efficient solar steam generation. The GO layer deposited on the microporous wood provides broad optical absorption and high photothermal conversion resulting in rapid increase in the temperature at the liquid surface. On the other hand, wood serves as a thermal insulator to confine the photothermal heat to the evaporative surface and to facilitate the efficient transport of water from the bulk to the photothermally active space. Owing to the tailored bilayer structure and the optimal thermo-optical properties of the individual components, the wood-GO composite structure exhibited a solar thermal efficiency of ∼83% under simulated solar excitation at a power density of 12 kW/m2. The novel composite structure demonstrated here is highly scalable and cost-efficient, making it an attractive material for various applications involving large light absorption, photothermal conversion and heat localization.

    View details for DOI 10.1021/acsami.7b01307

    View details for Web of Science ID 000395494200113

    View details for PubMedID 28151641

  • Metal-Organic Framework as a Protective Coating for Biodiagnostic Chips ADVANCED MATERIALS Wang, C., Tadepalli, S., Luan, J., Liu, K., Morrissey, J. J., Kharasch, E. D., Naik, R. R., Singamaneni, S. 2017; 29 (7)


    Zeolitic imidazolate framework-8 (ZIF-8) grown around antibodies anchored to plasmonic nanostructures serves as a protective layer to preserve the biorecognition ability of antibodies stored at room and elevated temperatures for several days. The biofunctionality of the ZIF-8-protected biochip can be restored by a simple water-rinsing step, making it highly convenient for use in point-of-care and resource-limited settings.

    View details for DOI 10.1002/adma.201604433

    View details for Web of Science ID 000396144600015

    View details for PubMedID 27925296

  • Structure-dependent SERS activity of plasmonic nanorattles with built-in electromagnetic hotspots. The Analyst Liu, K. K., Tadepalli, S. n., Wang, Z. n., Jiang, Q. n., Singamaneni, S. n. 2017; 142 (23): 4536–43


    Hollow plasmonic nanostructures with built-in and accessible electromagnetic hotspots such as nanorattles, obtained through a galvanic replacement reaction, have received wide attention in chemical and biological sensing and targeted drug delivery. In this study, we investigate the surface enhanced Raman scattering (SERS) activity of plasmonic nanorattles obtained through different degrees of galvanic replacement of Au@Ag nanocubes. We found that the SERS efficacy of the nanorattles is governed by the plasmon extinction intensity, localized surface plasmon resonance (LSPR) wavelength of the nanostructures with respect to the excitation source and intensity of the electromagnetic field at the hotspot, with the latter playing a determining role. Finite-difference time-domain (FDTD) simulations showed excellent agreement with the experimental findings that an optimal degree of galvanic replacement is critical for maximum SERS enhancement. The rational design and synthesis of the plasmonic nanorattles based on these findings can make these nanostructures highly attractive for SERS-based chemical and biological sensing and bioimaging.

    View details for PubMedID 29111555

  • Bilayered Biofoam for Highly Efficient Solar Steam Generation ADVANCED MATERIALS Jiang, Q., Tian, L., Liu, K., Tadepalli, S., Raliya, R., Biswas, P., Naik, R. R., Singamaneni, S. 2016; 28 (42): 9400-?


    A novel bilayered hybrid biofoam composed of a bacterial nanocellulose (BNC) layer and a reduced graphene oxide (RGO)-filled BNC layer is introduced for highly efficient solar steam generation. The biofoam exhibits a solar thermal efficiency of ≈83% under simulated solar illumination (10 kW m-2 ). The fabrication method introduced here is highly scalable and cost-efficient.

    View details for DOI 10.1002/adma.201601819

    View details for Web of Science ID 000391174600018

    View details for PubMedID 27432591

  • Silk-Encapsulated Plasmonic Biochips with Enhanced Thermal Stability ACS APPLIED MATERIALS & INTERFACES Wang, C., Luan, J., Tadepalli, S., Liu, K., Morrissey, J. J., Kharasch, E. D., Naik, R. R., Singamaneni, S. 2016; 8 (40): 26493-26500


    Because of their high sensitivity, cost-efficiency, and great potential as point-of-care biodiagnostic devices, plasmonic biosensors based on localized surface plasmon resonance have gained immense attention. However, most plasmonic biosensors and conventional bioassays rely on natural antibodies, which are susceptible to elevated temperatures and nonaqueous media. Hence, an expensive and cumbersome "cold chain" system is necessary to preserve the labile antibodies by maintaining optimal cold temperatures during transport, storage, and handling. Herein, we introduce a facile approach to preserve the antibody activity on a biosensor surface even at elevated temperatures. We show that silk fibroin film could be used as a protective layer to preserve the activity of a model antibody (Rabbit IgG) and cardiac troponin antibody at both room temperature and 40 °C over several days. Furthermore, a simple aqueous rinsing process restores the biofunctionality of the biosensor. This energy-efficient and environmentally friendly method represents a novel approach to eliminate the cold chain and temperature-controlled packing of diagnostic reagents and materials, thereby extending the capability of antibody-based biosensors to different resource-limited circumstances such as developing countries, an ambulance, an intensive care unit emergency room, and battlefield.

    View details for DOI 10.1021/acsami.6b07362

    View details for Web of Science ID 000385469000008

    View details for PubMedID 27438127

    View details for PubMedCentralID PMC5371827

  • PEGylated Artificial Antibodies: Plasmonic Biosensors with Improved Selectivity ACS APPLIED MATERIALS & INTERFACES Luan, J., Liu, K., Tadepalli, S., Jiang, Q., Morrissey, J. J., Kharasch, E. D., Singamaneni, S. 2016; 8 (36): 23509-23516


    Molecular imprinting, which involves the formation of artificial recognition elements or cavities with complementary shape and chemical functionality to the target species, is a powerful method to overcome a number of limitations associated with natural antibodies. An important but often overlooked consideration in the design of artificial biorecognition elements based on molecular imprinting is the nonspecific binding of interfering species to noncavity regions of the imprinted polymer. Here, we demonstrate a universal method, namely, PEGylation of the noncavity regions of the imprinted polymer, to minimize the nonspecific binding and significantly enhance the selectivity of the molecular imprinted polymer for the target biomolecules. The nonspecific binding, as quantified by the localized surface plasmon resonance shift of imprinted plasmonic nanorattles upon exposure to common interfering proteins, was found to be more than 10 times lower compared to the non-PEGylated counterparts. The method demonstrated here can be broadly applied to a wide variety of functional monomers employed for molecular imprinting. The significantly higher selectivity of PEGylated molecular imprints takes biosensors based on these artificial biorecognition elements closer to real-world applications.

    View details for DOI 10.1021/acsami.6b07252

    View details for Web of Science ID 000383412000009

    View details for PubMedID 27540627

    View details for PubMedCentralID PMC5371828

  • Polarization-Dependent Surface-Enhanced Raman Scattering Activity of Anisotropic Plasmonic Nanorattles JOURNAL OF PHYSICAL CHEMISTRY C Liu, K., Tadepalli, S., Kumari, G., Banerjee, P., Tian, L., Jain, P. K., Singamaneni, S. 2016; 120 (30): 16899-16906
  • Plasmonic Nanogels for Unclonable Optical Tagging ACS APPLIED MATERIALS & INTERFACES Tian, L., Liu, K., Fei, M., Tadepalli, S., Cao, S., Geldmeier, J. A., Tsukruk, V. V., Singamaneni, S. 2016; 8 (6): 4031-4041


    We demonstrate the fabrication of novel functional gel coatings with randomized physical and chemical patterns that enable dual encoding ability to realize unclonable optical tags. This design is based on swelling-mediated massive reconstruction of an ultrathin responsive gelatinous polymer film uniformly adsorbed with plasmonic nanostructures into a randomized network of interacting folds, resulting in bright electromagnetic hotspots within the folds. We reveal a strong correlation between the topology and near-field electromagnetic field enhancement due to the intimate contact between two plasmonic surfaces within the folds, each of them representing a unique combination of local topography and chemical distribution caused by the formation of electromagnetic hotspots. Because of the efficient trapping of the Raman reporters within the uniquely distributed electromagnetic hotspots, the surface enhanced Raman scattering enhancement from the morphed plasmonic gel was found to be nearly 40 times higher compared to that from the pristine plasmonic gel. Harnessing the nondeterministic nature of the folds, the folded plasmonic gel can be employed as a multidimensional (with dual topo-chemical encoding) optical taggant for prospective anticounterfeiting applications. Such novel optical tags based on the spontaneous folding process are virtually impossible to replicate because of the combination of nondeterministic physical patterns and chemical encoding.

    View details for DOI 10.1021/acsami.5b11399

    View details for Web of Science ID 000370583100058

    View details for PubMedID 26812528

  • Plasmonic paper: a porous and flexible substrate enabling nanoparticle-based combinatorial chemistry RSC ADVANCES Schmucker, A. L., Tadepalli, S., Liu, K., Sullivan, C. J., Singamaneni, S., Naik, R. R. 2016; 6 (5): 4136-4144

    View details for DOI 10.1039/c5ra21977a

    View details for Web of Science ID 000369508800087

  • Plasmonic Biofoam: A Versatile Optically Active Material NANO LETTERS Tian, L., Luan, J., Liu, K., Jiang, Q., Tadepalli, S., Gupta, M. K., Naik, R. R., Singamaneni, S. 2016; 16 (1): 609-616


    Owing to their ability to confine and manipulate light at the nanoscale, plasmonic nanostructures are highly attractive for a broad range of applications. While tremendous progress has been made in the synthesis of size- and shape-controlled plasmonic nanostructures, their integration with other materials and application in solid-state is primarily through their assembly on rigid two-dimensional (2D) substrates, which limits the plasmonically active space to a few nanometers above the substrate. In this work, we demonstrate a simple method to create plasmonically active three-dimensional biofoams by integrating plasmonic nanostructures with highly porous biomaterial aerogels. We demonstrate that plasmonic biofoam is a versatile optically active platform that can be harnessed for numerous applications including (i) ultrasensitive chemical detection using surface-enhanced Raman scattering; (ii) highly efficient energy harvesting and steam generation through plasmonic photothermal heating; and (iii) optical control of enzymatic activity by triggered release of biomolecules encapsulated within the aerogel. Our results demonstrate that 3D plasmonic biofoam exhibits significantly higher sensing, photothermal, and loading efficiency compared to conventional 2D counterparts. The design principles and processing methodology of plasmonic aerogels demonstrated here can be broadly applied in the fabrication of other functional foams.

    View details for DOI 10.1021/acs.nanolett.5b04320

    View details for Web of Science ID 000368322700093

    View details for PubMedID 26630376

  • Off-Resonant Gold Superstructures as Ultrabright Minimally Invasive Surface-Enhanced Raman Scattering (SERS) Probes CHEMISTRY OF MATERIALS Tian, L., Tadepalli, S., Fei, M., Morrissey, J. J., Kharasch, E. D., Singamaneni, S. 2015; 27 (16): 5678-5684
  • Size-Dependent Surface Enhanced Raman Scattering Activity of Plasmonic Nanorattles CHEMISTRY OF MATERIALS Liu, K., Tadepalli, S., Tian, L., Singamaneni, S. 2015; 27 (15): 5261-5270
  • Bio-Enabled Gold Superstructures with Built-In and Accessible Electromagnetic Hotspots ADVANCED HEALTHCARE MATERIALS Tian, L., Fei, M., Tadepalli, S., Morrissey, J. J., Kharasch, E. D., Singamaneni, S. 2015; 4 (10): 1502-1509


    The bio-enabled synthesis of a novel class of surface enhanced Raman scattering probes is presented for functional imaging with built-in and accessible electromagnetic hotspots formed between densely packed satellites grown on a plasmonic core. The superstructures serve as nanoscale sensors to spatiotemporally map intravesicular pH changes along endocytic pathways inside live cells.

    View details for DOI 10.1002/adhm.201500227

    View details for Web of Science ID 000358005500008

    View details for PubMedID 25981873

  • Hydrophilic, Bactericidal Nanoheater-Enabled Reverse Osmosis Membranes to Improve Fouling Resistance ACS APPLIED MATERIALS & INTERFACES Ray, J. R., Tadepalli, S., Nergiz, S. Z., Liu, K., You, L., Tang, Y., Singamaneni, S., Jun, Y. 2015; 7 (21): 11117-11126


    Polyamide (PA) semipermeable membranes typically used for reverse osmosis water treatment processes are prone to fouling, which reduces the amount and quality of water produced. By synergistically coupling the photothermal and bactericidal properties of graphene oxide (GO) nanosheets, gold nanostars (AuNS), and hydrophilic polyethylene glycol (PEG) on PA reverse osmosis membrane surfaces, we have dramatically improved fouling resistance of these membranes. Batch fouling experiments from three classes of fouling are presented: mineral scaling (CaCO3 and CaSO4), organic fouling (humic acid), and biofouling (Escherichia coli). Systematic analyses and a variety of complementary techniques were used to elucidate fouling resistance mechanisms from each layer of modification on the membrane surface. Both mineral scaling and organic fouling were significantly reduced in PA-GO-AuNS-PEG membranes compared to other membranes. The PA-GO-AuNS-PEG membrane was also effective in killing all near-surface bacteria compared to PA membranes. In the PA-GO-AuNS-PEG membrane, the GO nanosheets act as templates for in situ AuNS growth, which then facilitated localized heating upon irradiation by an 808 nm laser inactivating bacteria on the membrane surface. Furthermore, AuNS in the membrane assisted PEG in preventing mineral scaling on the membrane surface. In flow-through flux and foulant rejection tests, PA-GO-AuNS-PEG membranes performed better than PA membranes in the presence of CaSO4 and humic acid model foulants. Therefore, the newly suggested membrane surface modifications will not only reduce fouling from RO feeds, but can improve overall membrane performance. Our innovative membrane design reported in this study can significantly extend the lifetime and water treatment efficacy of reverse osmosis membranes to alleviate escalating global water shortage from rising energy demands.

    View details for DOI 10.1021/am509174j

    View details for Web of Science ID 000355891700009

    View details for PubMedID 25941970

  • Plasmonic Nanorattles with Intrinsic Electromagnetic Hot-Spots for Surface Enhanced Raman Scattering SMALL Jaiswal, A., Tian, L., Tadepalli, S., Liu, K., Fei, M., Farrell, M. E., Pellegrino, P. M., Singamaneni, S. 2014; 10 (21): 4287-4292


    The synthesis of plasmonic nanorattles with accessible electromagnetic hotspots that facilitate highly sensitive detection of chemical analytes using surface enhanced Raman scattering (SERS) is demonstrated. Raman spectra obtained from individual nanorattles demonstrate the significantly higher SERS activity compared to solid plasmonic nanostructures.

    View details for DOI 10.1002/smll.201401278

    View details for Web of Science ID 000344903500009

    View details for PubMedID 25045064

  • Multifunctional Hybrid Nanopatches of Graphene Oxide and Gold Nanostars for Ultraefficient Photothermal Cancer Therapy ACS APPLIED MATERIALS & INTERFACES Nergiz, S. Z., Gandra, N., Tadepalli, S., Singamaneni, S. 2014; 6 (18): 16395-16402


    Multifunctional hybrid nanomaterials with enhanced therapeutic efficiency at physiologically safe dosages for externally triggered, image-guided therapy are highly attractive for nanomedicine. Here, we demonstrate a novel class of multifunctional hybrid nanopatches comprised of graphene oxide (GO) and gold nanostars for enhanced photothermal effect and image-guided therapy. The hybrid nanopatches with tunable localized surface plasmon resonance into the near-infrared therapeutic window (650-900 nm) were realized using a biofriendly method that obviates the need for toxic shape-directing agents. Internalization of the intact nanopatches into epithelial breast cancer cells was confirmed by Raman imaging, transmission electron microscopy, and inductively coupled plasma mass spectrometry. It appears that the amphipathic nature and the large surface area of the graphene oxide enable it to serve as a soft, flexible, and biocompatible intracellular carrier for the in situ grown plasmonic nanostructures and provide long-term biocompatibility with extremely low cytotoxicity. Apart from a remarkably improved photothermal effect compared to that of either of the components at very low dosages of the hybrids (10 μg/mL GO) and using a low laser power (0.75 W cm(-2)), the hybrid nanopatches exhibit strong Raman scattering, making them excellent candidates for bioimaging, diagnostics, and image-guided therapy applications.

    View details for DOI 10.1021/am504795d

    View details for Web of Science ID 000342328300093

    View details for PubMedID 25152960

  • Bioplasmonic calligraphy for multiplexed label-free biodetection BIOSENSORS & BIOELECTRONICS Tian, L., Tadepalli, S., Park, S. H., Liu, K., Morrissey, J. J., Kharasch, E. D., Naik, R. R., Singamaneni, S. 2014; 59: 208-215


    Printable multi-marker biochips that enable simultaneous quantitative detection of multiple target biomarkers in point-of-care and resource-limited settings are a holy grail in the field of biodiagnostics. However, preserving the functionality of biomolecules, which are routinely employed as recognition elements, during conventional printing approaches remains challenging. In this article, we introduce a simple yet powerful approach, namely plasmonic calligraphy, for realizing multiplexed label-free bioassays. Plasmonic calligraphy involves a regular ballpoint pen filled with biofunctionalized gold nanorods as plasmonic ink for creating isolated test domains on paper substrates. Biofriendly plasmonic calligraphy approach serves as a facile method to miniaturize the test domain size to few mm(2), which significantly improves the sensitivity of the plasmonic biosensor compared to bioplasmonic paper fabricated using immersion approach. Furthermore, plasmonic calligraphy also serves as a simple and efficient means to isolate multiple test domains on a single test strip, which facilitates multiplexed biodetection and multi-marker biochips. Plasmonic calligraphy, which can be potentially automated by implementing with a robotic arm, serves as an alternate path forward to overcome the limitations of conventional ink-jet printing.

    View details for DOI 10.1016/j.bios.2014.03.043

    View details for Web of Science ID 000337855100031

    View details for PubMedID 24727607

    View details for PubMedCentralID PMC4044868

  • Multiplexed charge-selective surface enhanced Raman scattering based on plasmonic calligraphy JOURNAL OF MATERIALS CHEMISTRY C Tian, L., Tadepalli, S., Farrell, M. E., Liu, K., Gandra, N., Pellegrino, P. M., Singamaneni, S. 2014; 2 (27): 5438-5446

    View details for DOI 10.1039/c4tc00768a

    View details for Web of Science ID 000338601800025

  • Effect of Carbon Nanotube Dispersion on Mechanical Properties of Aluminum-Silicon Alloy Matrix Composites JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE Chandran, P., Sirimuvva, T., Nayan, N., Shukla, A. K., Murty, S. V., Pramod, S. L., Sharma, S. C., Bakshi, S. R. 2014; 23 (3): 1028-1037

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