Sustainable Growth and Lipid Production from <i>Chlorella pyrenoidosa</i> Using N‑Doped Carbon Nanosheets: Unravelling the Role of Graphitic Nitrogen

The advent of novel carbonaceous nanomaterials (CMs) associated with microalgae paved an alternate way for the bioeconomic production of biofuels as well as high value added compounds. Herein, we for the first time, present a holistic approach for sustainable biomass and lipid production from Chlorella pyrenoidosa, wherein CMs, namely N-doped carbon nanosheets (CNS) and N-doped graphene nanosheets (NGS) were used as one of the algal growth supporting factors. Doping carbon nanomaterials with nitrogen can effectively tune its electronic structure and other intrinsic properties for efficient photocatalysis. The utilization of CNS and NGS in this process lead to rapid, environment friendly, and facile assimilation of biomass and lipids for the development of nutraceuticals, pharmaceuticals, and other bioenergy associated applications. Employing a suite of characterization methods, the intrinsic structural and morphological properties of CMs were revealed. Compared with control, the lipid content obtained in the presence of undoped carbonized carbon materials (CCM), CNS, and NGS were found to be around 1.5-, 2-, and 6-fold higher, respectively, at similar growth conditions. We, therefore, envisage that graphitic nitrogen rich NGS plays a pivotal role in enhancing the lipid production from algae. This finding, therefore, exhibits a promising potential to bring about a paradigm shift in the field of bioenergy frameworks

Carbon Nanosheets Infused with Gold Nanoparticles as an Ultrasensitive Nose for Electrochemical Arsenic Sensing

Herein, we introduce an eco-friendly electrochemical sensor based on melamine-enriched nitrogen-doped carbon nanosheets decorated with gold nanoparticles (Au-CNSm) for arsenic sensing. An extremely facile, low-toxicity, biocompatible, and affordable hydrothermal technique was adopted for the synthesis of the Au-CNSm nanocomposite. The Au-CNSm-integrated sensing platform was optimized for electrode composition by cyclic voltammetry (CV). Owing to the synergistic effects of melamine-enriched carbon nanosheets (CNSm) and gold nanoparticles (AuNPs), the anodic peak current increased in the Au-CNSm-modified sensing electrode as compared to the CNSm-decorated platform. A wide linear range of 0.0001–100 μM and a low detection limit of 0.0001 μM were obtained. The visual signals can be measured at a very minute concentration of 0.0001 μM (0.1 ppb) on a screen-printed carbon electrode (SPCE) modified with Au-CNSm. Hence, this electrode system clearly outperformed the previously reported studies in terms of linear range, limit of detection (LOD), and electrocatalytic activity for arsenic sensing. Interestingly, the fabricated biosensor can be developed as a point-of-care device for real-time environmental monitoring for public safety. Henceforth, owing to exceptional attributes such as portability, selectivity, and sensitivity, this device offers great promise in modeling a revolutionary new class of electrochemical sensing platforms for an ultrasensitive and reliable detection strategy for arsenite (As(III))