Graphene-based sensors are exceptionally sensitive with high carrier mobility and low intrinsic noise, and have been intensively investigated in the past decade. The detection of individual gas molecules has been reported, albeit the underlying sensing mechanism is not yet well understood. We focus on the adsorption of ${\mathrm{NO}}_2$, ${\mathrm{H}}_2\mathrm{O}$, and ${\mathrm{NH}}_3$ on a molecular junction with a pyrene core, which can be considered as a minimal graphenelike unit. We systematically investigate the chemiresistive response within the framework of density functional theory and nonequilibrium Greens functions. We highlight the fundamental role of quantum interference (QI) in the sensing process, and we propose it as a paradigmatic mechanism for sensing. Owing to the open-shell character of ${\mathrm{NO}}_2$, its interaction with pyrene gives rise to a Fano resonance thereby triggering the strongest chemiresistive response, while the weaker interactions with ${\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{NH}}_3$ result in lower sensitivity. We demonstrate that by exploiting destructive QI arising in the meta-substituted pyrene, it is possible to calibrate the sensor to enhance both its sensitivity and chemical selectivity by almost two orders of magnitude so that individual molecules can be detected and distinguished. These results provide a fundamental strategy to design high-performance chemical sensors with graphene functional blocks.

Methicillin-resistant Staphylococcus epidermidis (MRSE) contamination is commonly found on human skin and medical devices. Herein, we present a sensor utilizing molecularly imprinted polymer nanobodies (nanoMIP) for recognition and electrochemical impedance spectroscopy (EIS) to detect S. epidermidis. Sensor manufacturing involves synthesizing nanoMIP via solid-phase synthesis using whole bacteria as templates. Screen-printed gold electrode (AuSPE)-modified 16-mercaptohexadecanoic acid (MHDA) served to immobilize the nanoMIPs on the sensor surface through an amide bond, with the remaining functional groups blocked by ethanolamine (ETA). Scanning electron microscope (SEM) analysis of the modified AuSPE surface reveals immobilized spherical nanoMIP particles of 114–120 nm diameter, while atomic force microscope (AFM) analysis showed increased roughness and height compared to bare AuSPE. The sensor is selective for S. epidermidis, with a remarkable detection limit of 1 CFU/mL. This research demonstrates that the developed nanoMIP-based sensor effectively detects S. epidermidis. Further research will focus on developing protocols to integrate the nanoMIP-based EIS sensor into medical and industrial applications, ultimately contributing to improved safety for both humans and animals in the future.

An indirect fluorescence sensing platform integrating molecularly imprinted polymer nanoparticles (MIP-NPs) and nitrogen-doped graphene quantum dots (N-GQDs) was developed for the rapid and selective determination of vancomycin (VA). MIP-NPs were synthesized using VA as a template to generate specific recognition sites, while a N-GQDs -based fluorescence probe (N-GQDs@GA@VA) was constructed by functionalizing N-GQDs with glutaraldehyde (GA) and vancomycin. The sensing strategy relies on an indirect signal transduction mechanism in which free VA molecules are first selectively captured by an excess amount of MIP-NPs, occupying the imprinted cavities. The number of remaining vacant binding sites subsequently regulates probe–MIP-NPs interactions, resulting in fluorescence quenching of the N-GQDs@GA@VA probe. Under optimized conditions, a stable fluorescence response was achieved within 10 min using 200 mg L⁻¹ of MIP-NPs. The proposed sensor exhibited a linear response over the concentration range of 0.5–80.0 mg L⁻¹ with a limit of detection of 0.45 mg L⁻¹. Satisfactory recoveries ranging from 86.7% to 110.0% with relative standard deviations (RSD) below 6% were obtained in spiked serum samples. Owing to its rapid response, high selectivity, and robust analytical performance, this indirect fluorescence platform demonstrates strong potential for therapeutic drug monitoring of vancomycin.