A novel magneto-active gel based nanomaterial system is presented as an externally tunable flow controller inside a microfluidic channel using the thermoresponsive property of the structure. Integration of ferromagnetic nanoparticles (Fe3O4) in the temperature sensitive polymer-poly (N-isopropylacrylamide) (PNIPAM) provides the swelling and de-swelling behavior of magnetic stimuli controlled micro-component by generating the heat due to the hysteresis loss of Fe3o4 under exposure in an alternating magnetic field. The shrinkage rates of the nanomaterial system at the bulk and micro scale are investigated. Size dependent shrinkage rate and actuation efficiency are ideal for various applications like magnetic micro/nano pump, magnetic field controlled drug delivery devices and magnetic switch applications.

In this study, protein micropatterns were created on the surface of three-dimensional hydrogel microstructures. Poly(ethylene glycol)(PEG)-based hydrogel microstructures were fabricated on a glass substrate using a poly(dimethylsiloxane) (PDMS) replica as a molding insert and photolithography. The lateral dimension and height of the hydrogel microstructures were easily controlled by the feature size of the photomask and depth of the PDMS replica, respectively. Bovine serum albumin (BSA), a model protein, was covalently immobilized to the surface of the hydrogel microstructure via a 5-azidonitrobenzoyloxy N-hydroxysuccinimide bifunctional linker, which has a phenyl azide group and a protein-binding N-hydroxysuccinimide group on either end. The immobilization of BSA on the PEG hydrogel surface was demonstrated with XPS by confirming the formation of a new nitrogen peak, and the selective immobilization of fluorescent-labeled BSA on the outer region of the three-dimensional hydrogel micropattern was demonstrated by fluorescence. A hydrogel microstructure could immobilize two different enzymes separately, and sequential bienzymatic reaction was demonstrated by reacting glucose and Amplex Red with a hydrogel microstructure where glucose oxidase was immobilized on the surface and peroxidase was encapsulated.

The immobilization of biomolecules on a solid substrate and their localization in “small” regions are major requirements for a variety of biomedical diagnostic applications, where rapid and accurate identification of multiple biomolecules is essential. In this specific application we have fabricated nanomitors for identifying specific protein biomarkers based on the electrical detection of antibody-antigen binding events.

The nanomonitor, lab-on-a-chip device technology is based on electrical detection of protein biomarkers. It is based on developing high density, low volume multi-well plate devices. The scientific core of this technology lies in integrating nanomaterial with micro fabricated chip platforms and exploiting the improve surface area to volume to improve the detection.

The devices that have been developed utilize electrical detection mechanisms where capacitance and conductance changes due to protein binding are used as “signatures” for biomarker profiling. In comparison to optical methods, the electrical detection technique is non-invasive as well as a label free. The signal acquisition is simple and it uses the existing data acquisition and signal analysis methods

We report on a short-wavelength, “blue” spectral shift of the photoluminescence (PL) spectrum in CdSeTe/ZnS core/shell quantum dots (QDs) caused by bioconjugation with several monoclonal cancer related antibodies (ABs). Scanning PL spectroscopy was performed on samples dried on solid substrates at various temperatures. The influence of the AB chemical origin on the PL spectral shift was observed. The conjugation QD-AB reaction was confirmed using the agarose gel electrophoresis technique. The spectral shift is strongly increased and the process facilitated when the samples are dried above room temperature. The PL spectroscopic mapping revealed a profile of the PL spectral shift across the dried QD-AB spot. Transmission Electron Microscopy analyses of the samples were performed to reveal the shape and size of individual QDs. A mechanism of the “blue” shift is attributed to changes in the QD electronic energy levels caused by local stress field applied to the bio-conjugated QD.

Pt, Ir, Au and few other precious metals have highly conducive electrical and chemical properties; hence have been widely used in pH sensors and bimolecular sensing applications. The chief objective of this research is to highlight and demonstrate the advantages that Iridium Oxide (IrOx) nanowires offer over these competing metals in improving the performance metrics of biomolecular sensing. Iridium oxide has very good conductivity and very high charge storing capacity, and hence has an ability to detect very small changes in the surface charge. Nanowires have an ideal morphology to crowd protein molecules and highly increase the surface area of interaction. Higher area of interaction along with iridium oxide's high intrinsic physical adsorption rate, strongly enhance the rate of immobilization of biomolecules and hence enabling high sensitivity detection. Inflammatory protein, C-Reactive protein (CRP) that is a biomarker for cardiovascular disease was used as the model biomolecule for this study.

In this study we describe preparation of polyionic hydrogels based on PEGylated polyamidoamine (PAMAM) dendrimers. Polyethylene glycol (PEG) with varied chain length (MW=1500, 6000, or 12000) was first conjugated to the Starburst™ G3.0 PAMAM dendrimer to form stealth dendrimers. The free hydroxyl group of PEG was further converted to an acrylate group using acrolyl chloride and triethylamine. The conjugation was characterized with 1H-NMR. The loading degree of PEG on the dendrimer surface was estimated by using both the ninhydrin assay and 1H-NMR. Hydrogel formation was realized by subjecting dendrimer-PEG acrylate to UV exposure for a brief period of time at the presence of Eosin Y, triethanolamine and 1-vinyl-2-pyrrolidinone. PEGylated G3.0 PAMAM dendrimer served as cross-linking agent to form hydrogels because of its multiple functionalities. The surface charges conferred by terminal groups on the dendrimer surface made the hydrogel polyionic with controllable charge density. This new type of hydrogel has many favorable biological properties such as non toxicity and non immunogenecity and multifunctional ties for a variety of in vivo applications. Current studies have demonstrated feasibility of chemistry and hydrogel formation.