The prevalence of mutated species of COVID-19 antigens has provided a strong impetus for identifying a cost-effective, rapid and facile strategy for identifying the viral loads in public places. The ever-changing genetic make-up of SARS-CoV-2 posts a significant challenfge for the research community to identify a robust mechanism to target, bind and confirm the presence of a viral load before it spreads. Synthetic DNA constructs are a novel strategy to design complementary DNA sequences specific for antigens of interest as in this review’s case SARS-CoV-2 antigens. Small molecules, complementary DNA and protein–DNA complexes have been known to target analytes in minimal concentrations. This phenomenon can be exploited by nanomaterials which have unique electronic properties such as ballistic conduction. Graphene is one such candidate for designing a device with a very low LOD in the order of zeptomolar and attomolar concentrations. Surface modification will be the significant aspect of the device which needs to have a high degree of sensitivity at the same time as providing a rapid signaling mechanism.

Rapid, accurate, and label-free detection of biomolecules and chemical substances remains a challenge in healthcare. Optical biosensors have been considered as biomedical diagnostic tools required in numerous areas including the detection of viruses, food monitoring, diagnosing pollutants in the environment, global personalized medicine, and molecular diagnostics. In particular, the broadly emerging and promising technique of surface plasmon resonance has established to provide real-time and label-free detection when used in biosensing applications in a highly sensitive, specific, and cost-effective manner with small footprint platform. In this study we propose a novel plasmonic biosensor based on biaxially crumpled graphene structures, wherein plasmon resonances in graphene are utilized to detect variations in the refractive index of the sample medium. Shifts in the resonance wavelength of the plasmon modes for a given change in the RI of the surrounding analyte are calculated by investigating the optical response of crumpled graphene structures on different substrates using theoretical computations based on the finite element method combined with the semiclassical Drude model. The results reveal a high sensitivity of 4990 nm/RIU, corresponding to a large figure-of-merit of 20 for biaxially crumpled graphene structures on polystyrene substrates. We demonstrate that biaxially crumpled graphene exhibits superior sensing performance compared with a uniaxial structure. According to the results, crumpled graphene structures on a titanium oxide substrate can improve the sensor sensitivity by avoiding the damping effects of polydimethylsiloxane substrates. The enhanced sensitivity and broadband mechanical tunability of the biaxially crumpled graphene render it a promising platform for biosensing applications.

Antibiotics are used against pathogens to treat bacterial infections, prevent disease spread, and reduce serious complications. Among them, Nitrofurantoin (NT) is widely utilized as a urinary antiseptic and anti-inflammatory medication. Due to safety concerns and associated disadvantages, NT is banned in several areas. Hence, it is essential to monitor the existence of NT to mitigate risks and ensure the safety of health and the environment. Therefore, an electrochemical sensing technique is applied to monitor the NT in various samples. Consequently, we have developed an electrochemical sensor based on the zeolitic imidazolate framework–derived zinc oxide/cobalt oxide/zinc cobalt oxide (Z-ZCO) with nitrogen-rich graphitic carbon nitride (GCN) electrocatalyst. The structural and morphological features of the developed sensor were studied with numerous spectroscopic techniques, and their performances were evaluated by significant measurements. Remarkably, our Z-ZCO/GCN displayed a huge surface area (0.158 cm²), faster reaction kinetics (k_et = 6.356 × 10⁻³ cm s⁻¹, k_s = 2.947 s⁻¹, and k_cat = 2.882 × 10³ M⁻¹ s⁻¹,), higher conductivity (53 Ω), lower detection limit (0.001 µM), lower quantification limit (0.005 µM), and optimal sensitivity (0.7139 µA µM⁻¹ cm⁻²), and superior selectivity. The practical application of monitoring NT in real samples resulted in phenomenal recoveries (92.1 to 103.2%). These outcomes suggest that our Z-ZCO/GCN is a prodigious electrochemical platform for the effective determination of NT.

Curvature-engineered graphene on SiO ₂ nanospheres forms nanoscale corrugations that redistribute charge and enhance plasmonic confinement, yielding strong field localization, high-Q resonances, and ultrasensitive refractive-index sensing.