Papers by Shantikumar Nair
Journal of Semiconductors, May 1, 2021
Major loss factors for photo-generated electrons due to the presence of surface defects in titani... more Major loss factors for photo-generated electrons due to the presence of surface defects in titanium dioxide (TiO2) were controlled by RF-sputtered tungsten trioxide (WO3) passivation. X-ray photoelectron spectroscopy assured the coating of WO3 on the TiO2 nanoparticle layer by showing Ti 2p, W 4f and O 1s characteristic peaks and were further confirmed by X-ray diffraction studies. The coating of WO3 on the TiO2 nanoparticle layer did not affect dye adsorption significantly. Dye sensitized solar cells (DSSCs) fabricated using WO3-coated TiO2 showed an enhancement of ~10% compared to DSSCs fabricated using pristine TiO2-based photo-electrodes. It is attributed to the WO3 passivation on TiO2 that creates an energy barrier which favored photo-electron injection by tunneling but blocked reverse electron recombination pathways towards holes available in highest occupied molecular orbital of the dye molecules. It was further evidenced that there is an optimum thickness (duration of coating) of WO3 to improve the DSSC performance and longer duration of WO3 suppressed photo-electron injection from dye to TiO2 as inferred from the detrimental effect in short circuit current density values. RF-sputtering yields pinhole-free, highly uniform and conformal coating of WO3 onto any area of interest, which can be considered for an effective surface passivation for nanostructured photovoltaic devices.
APL Bioengineering, 2021
Coronary in-stent restenosis and late stent thrombosis are the two major inadequacies of vascular... more Coronary in-stent restenosis and late stent thrombosis are the two major inadequacies of vascular stents that limit its long-term efficacy. Although restenosis has been successfully inhibited through the use of the current clinical drug-eluting stent which releases antiproliferative drugs, problems of late-stent thrombosis remain a concern due to polymer hypersensitivity and delayed re-endothelialization. Thus, the field of coronary stenting demands devices having enhanced compatibility and effectiveness to endothelial cells. Nanotechnology allows for efficient modulation of surface roughness, chemistry, feature size, and drug/biologics loading, to attain the desired biological response. Hence, surface topographical modification at the nanoscale is a plausible strategy to improve stent performance by utilizing novel design schemes that incorporate nanofeatures via the use of nanostructures, particles, or fibers, with or without the use of drugs/biologics. The main intent of this rev...
Neuro-Oncology Advances, 2021
BackgroundNanoparticle siRNA-conjugates are promising clinical therapeutics as indicated by recen... more BackgroundNanoparticle siRNA-conjugates are promising clinical therapeutics as indicated by recent US-FDA approval. In glioma stem cells (GSC), multiple stemness associated genes were found aberrant. We report intracranially injectable, multi-gene-targeted siRNA nanoparticle gel (NPG) for the combinatorial silencing of 3 aberrant genes, thus inhibiting the tumorogenic potential of GSCs.MethodsNPG loaded with siRNAs targeted against FAK, NOTCH-1, and SOX-2 were prepared by the self-assembly of siRNAs with protamine–hyaluronic acid combination. Electron microscopy, DLS, and agarose gel electrophoresis were used for the physicochemical characterization. Cell transfection and gene-silencing efficiency were studied using human mesenchymal stem cells and rat C6 glioma-derived GSCs. Neurosphere inhibition was tested in vitro using GSCs derived from C6 cell line and glioma patient samples. Patient-derived xenograft model and orthotopic rat glioma model were used to test the effect of NPG on...
Scientific reports, Jan 3, 2017
Theranostic nanoparticles based on biocompatible mineral compositions can significantly improve t... more Theranostic nanoparticles based on biocompatible mineral compositions can significantly improve the translational potential of image guided cancer nano-therapy. Here, we report development of a single-phase calcium phosphate biomineral nanoparticle (nCP) with dual-mode magnetic resonance contrast (T1-T2) together with radiofrequency (RF) mediated thermal response suitable for image-guided RF ablation of cancer. The nanoparticles (NP) are engineered to provide dual MR contrast by an optimized doping concentration (4.1 at%) of paramagnetic ion, Fe, which also renders lossy dielectric character for nCP leading to thermal response under RF exposure. In vivo compatibility and dual-mode MR contrast are demonstrated in healthy rat models. MRI and T2 mapping suggest hepatobiliary clearance by ~96 hours. MRI guided intratumoral injection in subcutaneous rat glioma and orthotopic liver tumor models provide clear visualization of NP in MRI which also helps in quantifying NP distribution within...
Scientific Reports, 2017
Localized and controlled delivery of chemotherapeutics directly in brain-tumor for prolonged peri... more Localized and controlled delivery of chemotherapeutics directly in brain-tumor for prolonged periods may radically improve the prognosis of recurrent glioblastoma. Here, we report a unique method of nanofiber by fiber controlled delivery of anti-cancer drug, Temozolomide, in orthotopic brain-tumor for one month using flexible polymeric nano-implant. A library of drug loaded (20 wt%) electrospun nanofiber of PLGA-PLA-PCL blends with distinct in vivo brain-release kinetics (hours to months) were numerically selected and a single nano-implant was formed by co-electrospinning of nano-fiber such that different set of fibres releases the drug for a specific periods from days to months by fiber-by-fiber switching. Orthotopic rat glioma implanted wafers showed constant drug release (116.6 μg/day) with negligible leakage into the peripheral blood (<100 ng) rendering ~1000 fold differential drug dosage in tumor versus peripheral blood. Most importantly, implant with one month release profi...
Journal of Functional Biomaterials, 2015
Injectable hydrogels are gaining popularity as tissue engineering constructs because of their eas... more Injectable hydrogels are gaining popularity as tissue engineering constructs because of their ease of handling and minimal invasive delivery. Making hydrogels from natural polymers helps to overcome biocompatibility issues. Here, we have developed an Amorphous Chitin (ACh)-Agarose (Agr) composite hydrogel using a simpletechnique. Rheological studies, such as viscoelastic behavior (elastic modulus, viscous modulus, yield stress, and consistency), inversion test, and injectability test, were carried out for different ACh-Agr concentrations. The composite gel, having a concentration of 1.5% ACh and 0.25% Agr, showed good elastic modulus (17.3 kPa), yield stress (3.8 kPa), no flow under gravity, injectability, and temperature stability within the physiological range. Based on these studies, the optimum concentration for injectability was found to be 1.5% ACh and 0.25% Agr. This optimized concentration was used for further studies and characterized using FT-IR and SEM. FT-IR studies confirmed the presence of ACh and Agr in the composite gel. SEM results showed that the lyophilized composite gel had good porosity and mesh like networks. The cytocompatibility of the composite gel was studied using human mesenchymal stem cells (hMSCs). The composite gels showed good cell viability.These results indicated that this injectable composite gel can be used for biomedical applications.
Tissue engineering. Part A, Jan 11, 2015
Our previous in vivo study showed that multi-layered scaffolds made of an angiogenic layer embedd... more Our previous in vivo study showed that multi-layered scaffolds made of an angiogenic layer embedded between an osteogenic layer and an osteoconductive layer, with layer thickness in the 100 - 400 μm range resulted in through-the thickness vascularization of the construct even in the absence of exogenous endothelial cells. The angiogenic layer was a collagen-fibronectin gel and the osteogenic layer was made from nanofibrous polycaprolactone while the osteoconductive layer was made either from microporous hydroxyapatite or microfibrous polycaprolactone. In this follow-up study, we implanted these acellular and cellular multi-layered constructs in critical sized rat calvarial defects and evaluated its vascularization and bone formation potential. Vascularization and bone formation at the defect was evaluated and quantified using microcomputed tomography (microCT) followed by perfusion of the animals with the radio opaque contrast agent Microfil. The extent of bony bridging and union wi...
Journal of Materials Chemistry A, 2015
The present manuscript analyzes the role of various carbon nanostructures in the photoanode and c... more The present manuscript analyzes the role of various carbon nanostructures in the photoanode and counter electrode of dye-sensitized solar cells.
Pectin is a natural polysaccharide and the pectin scaffold system has proved to be suitable for a... more Pectin is a natural polysaccharide and the pectin scaffold system has proved to be suitable for an intended use towards biomedical applications, such as drug delivery and tissue engineering. Studies on gemcitabine loaded pectin-fibrin scaffold have shown it to be cytotoxic towards ovarian cancer cells at the in vitro level. Our present study aims at substantiating the biocompatibility of the pectin-fibrin composite scaffold in a mouse implantation model in order to prove the compatibility of the scaffold system in vivo. Composite scaffolds were implanted and the biocompatibility was assessed after the 1 st , 6 th and 12 th week of study, respectively. Macroscopic inspection of the implantation site revealed no pathological inflammatory responses and histopathology studies depicted remarkable neutrophil accumulation within the implant in a timely manner. Furthermore, the immune response indicated significant difference with cytokines IL-1β, IL-10, and IL-17α, respectively. These results suggested that this scaffold system could be a promising targeted drug delivery system for the slow release of drugs in a mouse disease model.
Nanomaterials and Nanotechnology, 2014
Nanomedicine, as a relatively new offshoot of nanotechnology, has presented vast opportunities in... more Nanomedicine, as a relatively new offshoot of nanotechnology, has presented vast opportunities in biomedical research for developing novel strategies to treat diseases. In the past decade, there has been a significant increase in in vitro and preclinical studies addressing the benefits of nanomedicines. In this commentary, we focus specifically on the efficacy- and toxicity-related translational challenges of nanocarrier-mediated systems, and briefly discuss possible strategies for addressing such issues at in vitro and preclinical stages. We address questions related specifically to the balance between toxicity and efficacy, a balance that is expected to be substantially different for nanomedicines compared to that for a free drug. Using case studies, we propose a ratiometric assessment tool to quantify the overall benefit of nanomedicine as compared to free drugs in terms of efficacy and toxicity. The overall goal of this commentary is to emphasize the strategies that promote the ...
J. Mater. Chem. A, 2014
Self-cleaning and multifunctional materials are used in applications such as windows, solar panel... more Self-cleaning and multifunctional materials are used in applications such as windows, solar panels, cements, paints, and textiles. This state-of-the-art review summarizes the materials involved in self-cleaning and multifunctional coatings.
International journal of molecular sciences, 2011
Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells eit... more Tissue engineering/regeneration is based on the hypothesis that healthy stem/progenitor cells either recruited or delivered to an injured site, can eventually regenerate lost or damaged tissue. Most of the researchers working in tissue engineering and regenerative technology attempt to create tissue replacements by culturing cells onto synthetic porous three-dimensional polymeric scaffolds, which is currently regarded as an ideal approach to enhance functional tissue regeneration by creating and maintaining channels that facilitate progenitor cell migration, proliferation and differentiation. The requirements that must be satisfied by such scaffolds include providing a space with the proper size, shape and porosity for tissue development and permitting cells from the surrounding tissue to migrate into the matrix. Recently, chitin scaffolds have been widely used in tissue engineering due to their non-toxic, biodegradable and biocompatible nature. The advantage of chitin as a tissue e...
J. Mater. Chem. B, 2014
Developed Ag–TiO2 based large area SERS substrate that enables spectroscopic detection and classi... more Developed Ag–TiO2 based large area SERS substrate that enables spectroscopic detection and classification of oral squamous cell carcinoma with a specificity and sensitivity of 95.83% and 100%, respectively.
Tissue Engineering Part A, 2013
Tissue Engineering Part A, 2010
In this study, we evaluated the role of fiber size scale in the adhesion and spreading potential ... more In this study, we evaluated the role of fiber size scale in the adhesion and spreading potential of human mesenchymal stem cells (hMSCs) on electrospun poly(caprolactone) (PCL) nanofibrous and microfibrous scaffolds. The effect of in vivo regulators in inducing osteogenic differentiation of hMSCs on PCL nanofibrous scaffolds was investigated using osteogenic differentiation marker gene expression and matrix mineralization. Here, we report for the first time the influence of in vivo regulators in an in vitro setting with hMSCs for bone tissue engineering on PCL nanofibrous matrices. Our results indicated that hMSCs attached and spread rapidly on nanofibrous scaffolds in comparison to microfibrous PCL. Further, hMSCs proliferated well on the nanofibrous scaffolds. The cells on the nanofibrous PCL were found to differentiate into the osteoblast lineage and subsequently mineralize upon addition of in vivo osteogenic regulators. The attachment and spreading of hMSCs were more effective on the nanofibers compared with the microfibers despite the lower protein surface coverage (total adsorbed protein per unit fiber surface area) on nanofibers.
Tissue Engineering Part A, 2014
International Journal of Biological Macromolecules, 2013
An injectable composite gel was developed from alginic and hyaluronic acid. The ezymatically cros... more An injectable composite gel was developed from alginic and hyaluronic acid. The ezymatically cross-linked injectable gels were prepared via the oxidative coupling of tyramine modified sodium algiante and sodium hyaluronate in the presence of horse radish peroxidase (HRP) and hydrogen peroxide (H 2 O 2). The composite gels were prepared by mixing equal parts of the two tryaminated polymer solutions in 10U HRP and treating with 1.0% H 2 O 2. The properties of the alginate gels were significanly affected by the addition of hyaluronic acid. The percentage water absorption and storage modulus of the composite gels were found to be lower than the alginate gels. The alginate and composite gels showed lower protein release compared to hyaluronate gels in the absence of hyaluronidase. Even hyaluronate gels showed only approximately 10% protein release after 14 days incubation in phosphate buffer solution. ATDC-5 cells encapsulated in the injectable gels showed high cell viability. The composite gels showed the presence of enlarged spherical cells with significantly higher metabolic activity compared to cells in hyaluronic and alginic acid gels. The results suggest the potential of the composite approach to develop covalently cross-linked hydrogels with tuneable physical, mechanical, and biological properties.
International Journal of Biological Macromolecules, 2013
A 3D nanocomposite scaffold of chitosan, gelatin and nano-silica was fabricated by lyophilization... more A 3D nanocomposite scaffold of chitosan, gelatin and nano-silica was fabricated by lyophilization to test the hypothesis that incorporation of nano-SiO2 could produce a better candidate for bone tissue engineering compared to pure chitosan and chitosan/gelatin scaffolds. The prepared scaffold was characterized using SEM and FTIR. Porosity, density, swelling, degradation, mechanical integrity, biomineralization and protein adsorption studies, favored it in comparison to the conventional chitosan and chitosan/gelatin scaffolds. In vitro cyto-compatablity, cell attachment-proliferation, ALP activity studies performed using MG-63 cells, advocate its remarkable performance. These cumulative results indicate the prepared nanocomposite scaffold as a prospective candidate for bone tissue engineering.
Uploads
Papers by Shantikumar Nair