Gold nanoparticles (GNPs) have generated keen interest among researchers in recent years due to their excellent physicochemical properties.

Sensing of urea is the key component in the diagnosis of kidney related diseases and milk adulteration. Until now, the methods developed for urea sensing are not easy to perform, and very little attention has been paid to commercialization of such sensors. Herein, for the first time we report the low cost graphene nanoplatelets (GNPlts) based sensing platform for urea. Specifically edge functionalized GNPlts are used for keeping graphitic activity of graphene planes intact. We have successfully sensed variable ranges of urea concentrations from 0.1–0.8 mg ml⁻¹. The amperometeric characterization showed a linear variation in current as a function of urea concentration. The developed platform has a rapid response time of 15 s with good sensitivity (33 μA (mg ml⁻¹)⁻¹) and specificity. This developed nanoplatform could be highly beneficial for the development of an ultrasensitive, disposable, routine use sensor for urea.

Epoxy resins have been extensively utilized for mechanical strength applications in the field of aerospace, automobiles, marine, defence, etc. Improving the strength as well as fracture behaviour of the light weight materials is challenging. Present work is an attempt to enhance elastic modulus, hardness and fracture resistance simultaneously by reinforcing the epoxy (bisphenol-A) matrix with a new-age two-dimensional atomically thin graphene oxide filler. Wet chemical oxidation method was used to prepare graphene oxide sheets. Morphological study of the synthesized graphene oxide was carried out using scanning electron microscopy. Fourier-transformed infrared, ultraviolet–visible and Raman spectroscopic techniques were also employed to ascertain the synthesis of graphene oxide. The results confirmed the synthesis of well oxidized graphene oxide sheets. The prepared graphene oxide sheets were then sonicated in acetone solution to ensure better dispersion in the bisphenol-A graphene oxide nano-composite using 0.25, 0.5, 1.0 and 1.5 wt.% graphene oxide reinforcement. Solution mixing method was used to synthesize the polymer nano-composite. Scanning electron microscopy results revealed the smooth dispersion of graphene oxide in the bisphenol-A matrix. Nano-indentation of the bisphenol-A graphene oxide nano-composite showed a considerable jump in elastic modulus at 1 wt.% and hardness at 0.50 wt.% of graphene oxide reinforcement. Fracture resistance of bisphenol-A graphene oxide composite as represented by ratio of elastic modulus to hardness was enhanced by 24% as compared to the pristine bisphenol-A. Our results demonstrate a promising way to improve the mechanical characteristics of epoxy resins through graphene oxide reinforcement at low weight percentages.