Xihua University

The development of innovative materials capable of detecting heavy metal ions is a crucial goal in the field of environmental remediation. However, achieving high selectivity for specific metal ions remains a challenge. This study designs a novel imine-based COF via Schiff base condensation for efficient detection of cobalt ions (Co²⁺) in environmental samples. The π-conjugation system provides excellent fluorescence properties. The COF contains tertiary amine and imine structures with nitrogen and oxygen atoms, enabling coordination with Co²⁺ as a Lewis base. This interaction disrupts the conjugated structure, causing fluorescence quenching. The experimental results demonstrate that our proposed method stands out in Co²⁺ detection, distinguished by its remarkable simplicity, exceptional sensitivity, rapid response time, and easy operability. The novel imine-based COF sensor exhibits high sensitivity (limit of detection = 8.5 × 10^-13 M), excellent selectivity and stability in fluorescence detection, enabling accurate identification of Co²⁺ in complex environments. This research not only presents an efficient and practical approach for the detection of Co²⁺ but also offers novel theoretical perspectives on the design and application of imine-based COF. The findings lay a solid foundation for the development of COF-based environmental monitoring technologies.

Ofloxacin, a synthetic antimicrobial drug, exhibits significant therapeutic potential in combating various bacterial infections. The exploration of ofloxacin's antimicrobial properties and the unique catalytic activity of G-triplex(G3) DNAzymes demonstrate the continuous efforts to develop cutting-edge biosensors for bacterial detection. G3 outperforms G4 due to a short, easily generated and dissociated sequence, which allows G3 multimeric sequences to fold more accurately than G4 ones of equivalent length, resulting in higher activity for the formed G3/hemin. This study constructed a novel colorimetric DNAzyme biosensor based on G3/hemin for ofloxacin in food. Aptamer-functionalized Fe₃O₄ magnetic nanoparticles acted as magnetic separation and detection probes, while G3/hemin served as DNAzyme. Under the optimum condition, the presence of ofloxacin initiated the catalytic oxidation to yield a colored product to quantify the ofloxacin concentration with the linear range of 50-300 nmol/L. Under the optimized conditions, a limit of detection of 15.25 nmol/L was obtained by directly detecting the fluorescent signals, which shows obvious superiority over the previously reported methods. This method offers the advantages of simplicity, rapid detection, and high recovery rates in standardization experiments involving actual samples such as beef jerky and ham sausage, paving the way for its widespread implementation in the fields of biomedical diagnostics, environmental monitoring, and food safety.

Anabolic agents, synthetic derivatives of androgenic hormones, promote protein synthesis while inhibiting degradation, thereby enhancing muscle mass and strength. These properties drive their illicit use as performance-enhancing drugs in sports, despite severe health risks including dependency and life-threatening pathologies. Consequently, the World Anti-Doping Agency (WADA) prohibits their use. This study presents a highly sensitive surface-enhanced Raman spectroscopy (SERS) detection platform utilizing gold nanostars (GNS) for identifying four anabolic agents. Synthesized via a seed-mediated growth method, the GNS substrate exploits its multibranched morphology to generate localized electromagnetic field amplification, achieving exceptional SERS enhancement. Detection limits reached 4.47 × 10^-8 M for nandrolone, 7.59 × 10^-8 M for trenbolone, 8.71 × 10^-8 M for methandrostenolone, and 1.55 × 10^-7 M for stanozolol, marking a 10- to 100-fold sensitivity improvement over conventional methods. The label-free, rapid analysis capability of this GNS-SERS platform underscores its potential for anti-doping enforcement and clinical toxicology applications.