Ultrasensitive protein detection has considerable potential for early diagnosis and screening of diseases. Here, based on Hemin-catalyzed surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization, this work developed an assay for ultrasensitive fluorescent biosensing of proteins and established a thrombin fluorescent sensor. First, the amino-modified aptamer 1 was immobilized on Fe 3 O 4 magnetic beads, and then thrombin was added to form the aptamer 1-thrombin bioaffinity complex. Another thiol-modified aptamer 2 binds to bound thrombin to form a sandwich structure. Fluorescein O-methacrylate was used as the monomer, acetylacetone (ACAC) as the initiator, and Hemin as the catalyst. Through Hemin-catalyzed SI-RAFT polymerization, a large number of thrombin molecules are labeled with fluorescein O-methacrylate, resulting in severalfold amplification of the fluorescent signal. By detecting the fluorescent signal in thrombin from 1.0 fM to 0.1 nM, the proposed super sandwich strategy can detect thrombin at 0.98 fM, which is lower than the detection limit of most other methods.
Salmonellais a rapidly spreading and widespread zoonotic infectious disease that poses a serious threat to the safety of both poultry and human lives. Therefore, the timely detection ofSalmonellain foods and animals has become an urgent need for food safety. This work describes the construction of an aptamer-based sensor forSalmonelladetection, using Fe3O4magnetic beads and Ag@Au core–shell nanoparticles-embedded 4-mercaptobenzoic acid (4MBA). Leveraging the high affinity between biotin and streptavidin, aptamers were conjugated to Fe3O4magnetic beads. These beads were then combined with Ag@4MBA@Au nanoparticles functionalized with complementary aptamers through hydrogen bonding and π-π stacking interactions, yielding a SERS-based aptamer sensor with optimized Raman signals from 4MBA. When target bacteria are present, aptamer-conjugated magnetic beads exhibit preferential binding to the bacteria, leading to a decrease in the surface-enhanced Raman scattering (SERS) signal. And it was used for the detection of five different serotypes ofSalmonella, respectively, and the results showed that the aptamer sensor exhibited a good linear relationship between the concentration range of 102–108CFU/mL and LOD is 35.51 CFU/mL. The SERS aptasensor was utilized for the detection of spiked authentic samples with recoveries between 94.0 and 100.4%, which proved the usability of the method and helped to achieve food safety detection.
危险品化学品经营许可证（带存储）