Reza Abbasi

Detection of microbial contamination is essential for hygiene monitoring in food production, healthcare, and environmental settings. While ATP-based bioluminescence assays are widely used for assessing cleanliness, commercial luminometers are costly, require large sample volumes, are non-specific for bacteria, and exhibit low dynamic range that limit their use. We report here a compact biosensing platform for sensitive ATP quantification and species-selective detection of Escherichia coli by integrating SuperSnap ATP chemistry and MicroSnap E. coli enzyme-specific assays. We use a backside-illuminated CMOS image sensor operated in contact-mode, allowing efficient detection of chemiluminescence from sample volumes as low as 10 µL. ATP measurements in SuperSnap buffer exhibit strong linearity and good agreement with commercial luminometers both at low and high concentration ranges, with limits of detection down to 3.51 nM ATP. When normalized to total ATP amount, the CMOS-based platform achieves sensitivity close to the luminometer, despite 30-fold smaller sample volume. Importantly, while the luminometer response saturates at ~75 nM ATP, the CMOS-based system maintains quantification up to 200 nM, demonstrating significantly larger dynamic range, which is a key practical advantage for real-world hygiene monitoring. Species-selective detection of E. coli was demonstrated using MicroSnap chemistry, achieving a detection limit of approximately 412 CFU mL⁻¹ following a 6-hour enrichment and a 10-minute detection step. Selectivity was preserved in mixed bacterial samples containing Staphylococcus epidermidis, confirming enzyme-mediated specificity. These results establish CMOS-based bioluminescent biosensing as a low-cost, portable, and versatile tool for rapid hygiene monitoring and targeted microbial detection at the point-of-need.

Optical biosensors have emerged as a powerful tool in analytical biochemistry, offering high sensitivity and specificity in the detection of various biomolecules. This article explores the advancements in the integration of optical biosensors with microfluidic technologies, creating lab-on-a-chip (LOC) platforms that enable rapid, efficient, and miniaturized analysis at the point of need. These LOC platforms leverage optical phenomena such as chemiluminescence and electrochemiluminescence to achieve real-time detection and quantification of analytes, making them ideal for applications in medical diagnostics, environmental monitoring, and food safety. Various optical detectors used for detecting chemiluminescence are reviewed, including single-point detectors such as photomultiplier tubes (PMT) and avalanche photodiodes (APD), and pixelated detectors such as charge-coupled devices (CCD) and complementary metal–oxide–semiconductor (CMOS) sensors. A significant advancement discussed in this review is the integration of optical biosensors with pixelated image sensors, particularly CMOS image sensors. These sensors provide numerous advantages over traditional single-point detectors, including high-resolution imaging, spatially resolved measurements, and the ability to simultaneously detect multiple analytes. Their compact size, low power consumption, and cost-effectiveness further enhance their suitability for portable and point-of-care diagnostic devices. In the future, the integration of machine learning algorithms with these technologies promises to enhance data analysis and interpretation, driving the development of more sophisticated, efficient, and accessible diagnostic tools for diverse applications.

Sustainable functionalization of bacterial cellulose for cost‐effective bionanocomposites with desired properties has received growing attention in recent years. This article presents the results of work aimed at obtaining bionanocomposite materials based on bacterial cellulose, a natural and eco‐friendly material. Bacterial cellulose obtained from the Kombucha symbiotic culture of bacteria and yeast (SCOBY) fermentation process is functionalized by embedding with diatom frustules, silver nanoparticles (AgNPs), and poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). The effects of functionalization on mechanical, optical, plasmonic, electrical, chemiluminescent, and antimicrobial properties are evaluated. Morphological characteristics of the nanocomposites are studied using electron microscopy. Addition of diatom frustules introduced into the SCOBY culture media results in bionanocomposite materials with enhanced tensile strength and increased ultraviolet (UV) blockage properties. In situ functionalization of bacterial cellulose with AgNPs tunes plasmonic and chemiluminescent properties, revealing the biosensing potential of the material. Modified bacterial cellulose shows antimicrobial activity in experiments with gram‐positive and gram‐negative bacteria. Dual functionalization of bacterial cellulose with PEDOT:PSS and AgNPs results in improved electrical conductivity of the bionanocomposite. Overall, bottom‐up physical functionalization approaches and the resulting bionanocomposite materials will open up new opportunities for the low‐cost production of green materials and contribute to the development of a sustainable economy.