We investigated physiological and subjective responses to morning light exposure of commercially available LED lighting with different correlated colour temperatures to predict how LED-based smart lighting employed in future learning environments will impact students. The classical markers of the circadian system (melatonin and cortisol), as well as the subjective perception of sleepiness, mood, and visual comfort, were compared. Fifteen university students underwent an hour of morning light exposure to both warm (3,500 K) and blue-enriched (6,500 K) white lights at recommended illuminance levels for classrooms and lecture halls (500 lux). The decline of melatonin levels was significantly greater after the exposure to blue-enriched white light. Exposure to blue-enriched white light significantly improved subjective perception of alertness, mood, and visual comfort. With regard to cortisol, we did not find a significant difference in the cortisol decrement between the two light conditions. Our findings suggest that the sensitivity of physiological and subjective responses to white LED light is blue-shifted. These findings, extending the already known effects of short-wavelength light on human physiology, reveal interesting practical implications. Blue-enriched LED light seems to be a simple yet effective potential countermeasure for morning drowsiness and dozing off in class, particularly in schools with insufficient daylight.

A simple and facile method for sensing of nucleic acids is in great need for disease biomarker detection and diagnosis. Herein, a fluorescent nanosensor utilizing carbon dot nanoparticles is introduced that form visible precipitates in the presence of target DNA. Carbon dot nanoparticles are fabricated by microwave pyrolysis of polyethylenimine, which emits strong photoluminescence and can form precipitates when added to target DNA oligonucleotides. The precipitates can be easily visualized by UV illumination, and data can be acquired as images using a smartphone, which are analyzed for quantification. This carbon-dot-based assay allowed fluorescent sensing of target oligonucleotides with various sizes and visualization even with minimal amount of DNA (≈100 pmol). Finally, the assay can be applied as a nanosensor platform for detecting bacterial DNA for the antibiotic-resistance gene KPC-2 from Klebsiella pneumoniae. This method provides a simple technique for detecting molecular targets, showing wide applicability for diagnostics on the bedside or point-of-care testing.

A rapid, colorimetric assay based on aggregation of nanobeads functionalized with vancomycin is developed for naked-eye detection of Gram-positive bacteria.