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Biomedical subjects

Satish Nayak

Publications and source records attributed to Satish Nayak.

4 recordsLinked to original sources

Soft nanotechnology with soft nanoparticles.

The last decade of research in the physical sciences has seen a dramatic increase in the study of nanoscale materials. Today, "nanoscience" has emerged as a multidisciplinary effort, wherein obtaining a fundamental understanding of the optical, electrical, magnetic, and mechanical properties of nanostructures promises to deliver the next generation of functional materials for a wide range of applications. While this range of efforts is extremely broad, much of the work has focused on "hard" materials, such as Buckyballs, carbon nanotubes, metals, semiconductors, and organic or inorganic dielectrics. Meanwhile, the soft materials of current interest typically include conducting or emissive polymers for "plastic electronics" applications. Despite the continued interest in these established areas of nanoscience, new classes of soft nanomaterials are being developed from more traditional polymeric constructs. Specifically, nanostructured hydrogels are emerging as a promising group of materials for multiple biotechnology applications as the need for advanced materials in the post-genomic era grows. This review will present some of the recent advances in the marriage between water-swellable networks and nanoscience.

Journal Article↗

Bioresponsive hydrogel microlenses.

We report investigations of bioresponsive hydrogel microlenses as a new protein detection technology. Stimuli-responsive poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAm-co-AAc) microgels have been synthesized via free-radical precipitation polymerization. These hydrogel microparticles were then functionalized with biotin via EDC coupling. Hydrogel microlenses were prepared from the particles via Coulombic assembly onto a silane-modified glass substrate. Arrays containing both pNIPAm-co-AAc microgels (as an internal control) and biotinylated pNIPAm-co-AAc microgels were then used to detect multivalent binding of both avidin and polyclonal anti-biotin. Protein binding was determined by monitoring the optical properties of the microlenses using a brightfield optical microscopy technique. The microlens method is shown to be very specific for the target protein, with no detectable interference from nonspecific protein binding. Finally, the reversibility of the hydrogel microlens assay has been studied in the case of anti-biotin to determine the potential application of the microlens assay technology in a displacement-type assay. These results suggest that the microlens method may be an appropriate one for label-free detection of proteins or small molecules via displacement of tethered protein--ligand pairs.

Acrylamides↗

Folate-mediated cell targeting and cytotoxicity using thermoresponsive microgels.

We describe the design of fluorescent, thermoresponsive microgels surface-functionalized with folic acid. Incubation of these particles with KB cells grown in folate-free medium results in efficient endocytosis of the particles via a receptor-mediated pathway. Laser scanning confocal microscopy and flow cytometry show efficient uptake of folate-modified particles over cationic control particles. Staining of the cells with Lysotracker red, followed by confocal imaging, shows anticorrelation between the particle and endosome fluorescence, which is taken as evidence of particle escape from the endosomes to the cytosol. Finally, the strong dependence of particle swelling on temperature was used to induce particle collapse and aggregation following uptake, which causes significant cytotoxicity. Thus, we have developed polymeric nanoparticles that may display antitumor activity, as they effectively target cancer cells and undergo endosomal escape to the cytosol, and they can then be triggered to cause cell death.

Carrier Proteins↗