Precise detection of 3-hydroxybutyrate (HB) in biological samples is of great importance for management of diabetic patients. In this study, an HB biosensor based on single-walled carbon nanotubes (SWCNTs)-modified screen-printed electrode (SPE) was developed to determine the concentration of HB in serum. The specific detecting enzyme, HB dehydrogenase, was physically immobilised on SWCNTs deposited on the surface of SPEs. The electrochemical measurement of HB that involved cyclic voltammetry was based on the signal produced by β-nicotinamide adenine dinucleotide (NADH), one of the products of the enzymatic reaction. The application of SWCNT reduced the oxidation potential of NADH to about −0.05 V. Electrochemical measurements showed that the response of this biosensor had relevant good linearity in the range of 0.1–2 mM with a low detection limit of 0.009 mM. Investigation of biosensor response in the presence of interfering molecules verified its specificity. Furthermore, the study of long-term stability demonstrated the acceptable efficiency of this biosensor for about 100 days.

This study presents a review on biosensors with an emphasis on recent developments in the field. A brief history accompanied by a detailed description of the biosensor concepts is followed by rising trends observed in contemporary micro- and nanoscale biosensors. Performance metrics to quantify and compare different detection mechanisms are presented. A comprehensive analysis on various types and subtypes of biosensors are given. The fields of interest within the scope of this review are label-free electrical, mechanical and optical biosensors as well as other emerging and popular technologies. Especially, the latter half of the last decade is reviewed for the types, methods and results of the most prominently researched detection mechanisms. Tables are provided for comparison of various competing technologies in the literature. The conclusion part summarises the noteworthy advantages and disadvantages of all biosensors reviewed in this study. Furthermore, future directions that the micro- and nanoscale biosensing technologies are expected to take are provided along with the immediate outlook.

Nanoenabled drug carriers are emerging as alternatives to conventional small-molecule drugs and their in-vitro biocompatibility evaluation with blood components is a necessary part of early preclinical development. In the present study, Chitosan-based bionanocomposites of sol–gel derived TiO₂ and SiO₂ were synthesised by the ex situ process. Samples were characterised by X-ray diffraction, Fourier transformed infrared spectrophotometer, transmission electron microscopy and selected area electron diffraction techniques. The analysis reveals the formation of single-phase oxides and their bionanocomposites. Haemolysis (destruction of red blood cell) study was performed by spectrophotometer to assess the haemocompatibility nature as a function of different incubation time. Experimental results reveal the percentage of haemolysis increase with the increase of the incubation time, but it was found to be <2%. This confirms our bionanocomposites are more haemocompatible as compared with respective nanocrystalline ceramics. Also, the interaction of our bionanocomposites with serum proteins at various incubation periods (1–24 h) were investigated using sodium dodecyl sulphate–polyacrylamide gel experiment, the obtained results were discussed in details.

Till date several methods of chemical synthesis of silver nanoparticles (AgNps) are known. Most of the protocol dealing with the chemical synthesis of AgNps involves high pressure, temperature, energy and technical skills. Thus, a method with much greener approach is the need of the hour. Accordingly, the authors have developed a method that is cost-effective, energy-efficient and easy method for the synthesis of AgNps. The AgNps were synthesised by using white sugar and sodium hydroxide (NaOH) in the presence of sunlight. These nanoparticles were characterised by visual observation, ultraviolet–visible (UV–vis) spectrophotometry, Fourier transform infrared (FTIR), nanoparticle tracking and analysis (NTA) and transmission electron microscopy (TEM). The effect of NaOH on the rate of AgNps synthesis was also studied. Formation of AgNps was primarily detected by change in colour of reaction mixture from colourless to yellow after treatment with 1 mM silver salt (AgNO₃). UV–vis spectroscopy showed peak at 409 nm. NTA revealed the polydispersed nature of nanoparticles, 15–30 nm in diameter. FTIR showed the presence of gluconic acid as capping agent, which increases the stability of AgNps in the colloids. TEM demonstrated the presence of spherical AgNps in the range of 10–25 nm. The present method confirms the synthesis of AgNps by using white sugar and NaOH. This method is simple, eco-friendly and economically sustainable, making it amenable to large-scale industrial production of AgNps.