Biocompatible thermoresponsive N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide-based random copolymer: synthesis and studies of its composition dependent properties and anticancer drug delivery efficiency.

A new acrylamide monomer, N-isopropyl-N-(3-(isopropylamino)-3-oxopropyl)acrylamide (M3i), consisting of both isopropyl and isopropylamidopropyl moieties, has been synthesized from isopropylamine and N-isopropylacrylamide via an aza-Michael addition reaction followed by amidation with acryloyl chloride. The homopolymer of M3i (polyM3i) and a series of random copolymers of M3i and poly(ethylene glycol)methyl ether acrylate (PEGA: CH2CHCO2(CH2CH2O)nMe, Mn = 480, n = 9 on average) with varying compositions have been synthesized via reversible addition-fragmentation chain transfer polymerization using 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) as well as 1-phenylethyl phenyl dithioacetate (PEPD) as a RAFT agent. These polymers have been characterized by 1H NMR, FTIR, GPC, UV-Vis, fluorescence, TGDTA, DSC, DLS, and TEM techniques. A lower critical solution temperature (LCST) and glass transition temperature (Tg) for polyM3i prepared using DDMAT were observed at 17 and 133 °C, respectively, while for a polymer formed using PEPD, no LCST was observed until 0 °C and its observed Tg was found at 127.3 °C. The polymers are thermally stable up to 300 °C. Upon an increase in the M3i content in the copolymers, LCST decreases, Tg increases, and the apparent hydrodynamic diameter decreases. Moreover, the effects of concentration and the addition of urea and sodium chloride on the LCST of the copolymer with an LCST close to body temperature were studied. Owing to the incorporation of PEGA, a higher critical micellar concentration and larger TEM particle size of this copolymer were observed with respect to those of polyM3i. The usefulness of the micelles of the copolymers as nano-carriers for the drug doxorubicin was explored. The in vitro tumoricidal activity of the micelles of the doxorubicin-loaded copolymers was also assessed against Dalton's lymphoma cells.

Functionalized polyurethane composite gel electrolyte with cosensitized photoanode for higher solar cell efficiency using a passivation layer.

Graphene oxide was chemically tagged with thermoplastic polyurethane, chain extended using butanediol to obtain the varying molecular weight of the polymer. Graphene-tagged polyurethane was functionalized using propane sultone to introduce the polar sulphonate groups in the main chain. The chain extension, tagging of GO and functionalization have been verified through spectroscopic techniques such as NMR, FTIR, UV and gel permeation chromatography. Thermal stability and the nature of the interaction were explored through thermal measurements to understand the effect of GO and functionalization. Electrical conduction was improved by the chemical attachment of graphene with the polymer (5.08 × 10-7 S cm-1), which further increases through functionalization and subsequent use of the additive (1.07 × 10-3 S cm-1) and make them suitable for gel electrolyte, being in the range of semiconductors. Quantum dots of CdS and CdSe were prepared using a capping agent and their characteristic properties and dimensions were worked out for their suitability as active materials in a solar cell. The optical band gap of quantum dots and HOMO/LUMO band structure of functionalized polyurethanes were measured using UV-vis and cyclic voltammetry, and thereby, constructing the overall energy diagrams for a possible combination of materials. Conducting carbon has been incorporated in the gel electrolyte to modulate the conductivity, while the ZnSe layer has been inserted as a passivation layer between the active material and the gel electrolyte. Solar cell devices were fabricated using the suitable materials, through the suitable energy diagram, and found a significantly high power conversion efficiency of 1.71%. The reason behind the improved efficiency is understood from the greater light harvesting behaviour, higher level of conductivity and blocking capacity of the various layered structures to reduce the electron-hole pair recombination.

Colorimetric detection of hydrogen peroxide and cholesterol using Fe3O4-brominated graphene nanocomposite.

Fe3O4-brominated graphene (Fe3O4-GBR) nanocomposites were synthesized via an in situ method using the precursors FeSO4.7H2O and GBR in different (1:1, 1:2, 2:1, 1:5, 1:10, 1:20, and 5:1) weight ratios at pH 11.5. The Fe3O4-GBR (1:5) nanocomposite in combination with H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB) showed swift and superior intrinsic peroxidase mimetic enzyme activity compared with the other Fe3O4-GBR composites, GBR and Fe3O4, as observed by colorimetry. It was characterized using high-resolution scanning electron microscopy (HRSEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA). Its catalytic activity was optimized by varying different parameters, and the optimum conditions for peroxidase mimetic activity were observed using 100 µL Fe3O4-GBR (1 mg/mL), 50 µL TMB (1 mg/mL), and 200 µL H2O2(1 mM) in 400 µL of acetate buffer of pH 2.3 at 30 °C temperature. Kinetic analysis has revealed the Michaelis-Menten kinetic behavior of peroxidase activity with Michaelis-Menten constants (Km) and maximum initial velocities (Vmax) of 0.082 mM and 14.1 nMs-1 respectively, for H2O2 and 0.086 mM and 5.1 nMs-1, respectively for TMB. The limit of detection and linear range were found to be 49.6 µM and 100-880 µM, respectively, for H2O2 and 41.9 µM and 47.6-952.3 µM, respectively, for cholesterol. On this basis, a simple, swift, sensitive, selective, and reproducible colorimetric assay to detect cholesterol levels in blood serum samples using Fe3O4-GBR nanocomposite has been developed. Thus, Fe3O4-GBR composite as compared to Fe3O4 and GBR has shown better peroxidase mimicking activity for biosensing.