The development of simple, sensitive, and efficient methods for antibiotic detection is of great significance for human health and environmental protection. Currently, although the competitive immunoassays are popular for detecting antibiotic molecules, they need to label antibiotic or specific antibody with signaling molecule. The development of noncompetitive immunoassay for antibiotic detection has always faced significant challenges. Herein, we have developed a light-assisted noncompetitive immunoassay for the detection of antibiotics based on their photosensitive characteristic. Firstly, the antibody coated on the microplate specifically captures the target antibiotic. Afterward, under light irradiation, the captured photosensitive antibiotic produces reactive oxygen species (ROS), which oxidizes the added ROS dye to generate a fluorescent signal. Therefore, a noncompetitive immunoassay for antibiotic detection is achieved by utilizing the unique property of photosensitive antibiotics to generate ROS instead of labeling signaling molecules. By using antibiotics demeclocycline hydrochloride (DMCO) and polymyxin B (PMB) as research models, the proposed noncompetitive fluorescence immunoassay can specifically detect as low as 5 ng/mL DMCO and 70 ng/mL PMB, respectively. The light-assisted noncompetitive immunoassay strategy opens a new avenue for simple, sensitive, label-free, and high-throughput detection of photosensitive antibiotics or photosensitive drugs. Based on the unique photosensitive property of antibiotics, a light-assisted noncompetitive immunoassay is developed for the detection of photosensitive antibiotics by integrating a one-step immunoassay and the fluorescence detection of reactive oxygen species under light irradiation. The light-assisted noncompetitive immunoassay strategy opens a new avenue for the simple, sensitive, label-free, and high-throughput detection of photosensitive antibiotics or photosensitive drugs.image

The ligase chain reaction (LCR), as a classic nucleic acid amplification technique, is popular in the detection of DNA and RNA due to its simplicity, powerfulness, and high specificity. However, homogeneous and ultrasensitive LCR detection is still quite challenging. Herein, we integrate the LCR with a CRISPR-Cas12a system to greatly promote the application of the LCR in a homogeneous fashion. By employing microRNA as the model target, we design LCR probes with specific protospacer adjacent motif sequences and the guide RNA. Then, the LCR is initiated by target microRNA, and the LCR products specifically bind to the guide RNA to activate the Cas12a system, triggering secondary signal amplification to achieve ultrasensitive detection of microRNA without separation steps. Moreover, by virtue of a cationic conjugated polymer, microRNA can not only be visually detected by naked eyes but also be accurately quantified based on RGB ratio analysis of images with no need of sophisticated instruments. The method can quantify microRNA up to 4 orders of magnitude, and the determination limit is 0.4 aM, which is better than those of other reported studies using CRISPR-Cas12a and can be compared with that of the reverse-transcription polymerase chain reaction. This study demonstrates that the CRISPR-Cas12a system can greatly expand the application of the LCR for the homogeneous, ultrasensitive, and visual detection of microRNA, showing great potential in efficient nucleic acid detection and in vitro diagnosis.

We report a photosensitive polymyxin B-modified conjugated oligomer nanoparticle that integrates the targeted identification and synergistic photodynamic therapy in one treatment against resistant Gram-negative bacteria. The study expands the application of antibiotics and opens a new avenue for enhancing photodynamic antimicrobial therapy and fighting bacterial resistance.