Amylase inhibitors, also known as starch blockers, contain substances that prevent dietary starches from being absorbed by the body via inhibiting breakdown of complex sugars to simpler ones. In this sense, these materials are projected as having potential applications in diabetes control. In this context, we report on zinc oxide nanoparticles as possible alpha-amylase inhibitors. Zinc oxide nanoparticles have been synthesized using soft-chemistry approach and 1-thioglycerol was used as a surfactant to yield polycrystalline nanoparticles of size ∼18 nm, stabilized in wurtzite structure. Conjugation study and structural characterization have been done using x-ray diffraction technique, Fourier transform infrared spectroscopy, UV-visible spectroscopy, and transmission electron microscopy. Cytotoxicity studies on human fibrosarcoma (HT-1080) and skin carcinoma (A-431) cell lines as well as mouse primary fibroblast cells demonstrate that up to a dose of 20 μg/ml, ZnO nanoparticles are nontoxic to the cells. We report for the first time the alpha-amylase inhibitory activity of ZnO nanoparticles wherein an optimum dose of 20 μg/ml was sufficient to exhibit 49% glucose inhibition at neutral pH and 35 °C temperature. This inhibitory activity was similar to that obtained with acarbose (a standard alpha-amylase inhibitor), thereby projecting ZnO nanoparticles as novel alpha-amylase inhibitors.

An extremely compact metamaterial microstrip sensor based on complementary split-ring-resonators (CSRRs) has been fabricated for chemical sensing. This device exhibits a resonance with high rejection at 4.5 GHz, which demonstrates concomitant variations when exposed to liquids of various permittivity values. The resonance frequency of CSRR is sensitive to the change in nearby dielectric material. The sensing of petrol shows a shift in frequency with a sharp dip in transmission, while, with ethanol, the frequency shift is accompanied with increase in the power of the signal. The ultra-fast reversibility and repeatability offers good headway towards hybrid fuel sensing applications.

Therapeutic agents or agricultural fertilizers captured in polymer colloids (PCs) give rise to interesting applications, which are typically related to sustained release. We synthesized crosslinked polymer structures with poly(vinyl alcohol) (PVA) and borax precursors. Fourier transform infrared spectroscopy showed that a polymer-boron ion complex was formed with the crosslinking reaction at the OAH site of PVA; thereby, PCs were formed. Field-emission scanning electron microscopy showed that a uniform mesoporous two-dimensional structure formed via intermolecular and intramolecular crosslinking. Trypsin enzyme and phosphate fertilizer were trapped in these PCs independently to study sustained release. Fertilizer-incorporated PCs were mixed with soil samples, in which seeds of fenugreek were sown, and the plant growth was monitored a duration of 15 days. The fertilizer release, studied with UV-visible spectroscopy, showed a sustained signature of the fertilizer (at 690 nm) in the water extracts of soil, with much healthier plant growth compared to the control. For the trypsinincorporated PC samples, the released enzyme was made to interact with bovine serum albumin protein to monitor the released percentage with UV absorption spectroscopy. A systematic increase in the enzyme signature (at 280 nm) was observed for a duration of 60 min; this indicated the potential of PC for sustained drug release. The swelling calculations predicted that the mechanism involved was composed of pseudo-swelling behavior. We envisaged that the hydroxyl groups of the PC broke in water and formed a complex with water. This complex slowly dissolved in water to release the entrapped molecules.

Polycrystalline rutile films of SnO2 (∼1500 Å) were deposited on Al2O3. Film imaging showed regular ellipsoidal nanostructured growth. Different concentrations (1000–3000 U) of glucose oxidase (GOx) were immobilized on SnO2 surface. Upon interaction with various glucose concentrations (65–300 mg/dl), films showed pronounced change in their sheet resistance with recovery and repeatability. Nanostructured SnO2 surfaces probably enhance adsorption of oxygen moieties. These convert to their ions by extracting electron/s from the conduction band of SnO2, which further interacts with H+, formed during the GOx-glucose interaction. This releases the trapped electron to the conduction band of SnO2, justifying its role as a catalyst.

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