To satisfy the need to develop highly sensitive methods for detecting the severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) and further enhance detection efficiency and capability, a new method was created for detecting SARS-CoV-2 of the open reading frames 1ab (ORF1ab) target gene by a electrochemiluminescence (ECL) biosensor based on dual-probe hybridization through the use of a detection model of “magnetic capture probes—targeted nucleic acids—Ru(bpy)₃²⁺ labeled signal probes”. The detection model used magnetic particles coupled with a biotin-labeled complementary nucleic acid sequence of the SARS-CoV-2 ORF1ab target gene as the magnetic capture probes and Ru(bpy)₃²⁺ labeled amino modified another complementary nucleic acid sequence as the signal probes, which combined the advantages of the highly specific dual-probe hybridization and highly sensitive ECL biosensor technology. In the range of 0.1 fM~10 µM, the method made possible rapid and sensitive detection of the ORF1ab gene of the SARS-CoV-2 within 30 min, and the limit of detection (LOD) was 0.1 fM. The method can also meet the analytical requirements for simulated samples such as saliva and urine with the definite advantages of a simple operation without nucleic acid amplification, high sensitivity, reasonable reproducibility, and anti-interference solid abilities, expounding a new way for efficient and sensitive detection of SARS-CoV-2.

The rapid and sensitive detection of pathogenic and suspicious bioaerosols are essential for public health protection. The impact of pollen on the identification of bacterial species by Raman and Fourier-Transform Infrared (FTIR) spectra cannot be overlooked. The spectral features of the fourteen class samples were preprocessed and extracted by machine learning algorithms to serve as input data for training purposes. The two types of spectral data were classified using classification models. The partial least squares discriminant analysis (PLS-DA) model achieved classification accuracies of 78.57% and 92.85%, respectively. The Raman spectral data were accurately classified by the support vector machine (SVM) algorithm, with a 100% accuracy rate. The two spectra and their fusion data were correctly classified with 100% accuracy by the random forest (RF) algorithm. The spectral processed algorithms investigated provide an efficient method for eliminating the impact of pollen interference.

This paper proposes a novel strategy for low humidity detection, an optical waveguide (OWG) sensor that is locally coated with polyvinylpyrrolidone (PVP) film. The humidity sensor was fabricated using a spin coating on a K+-exchanged glass optical waveguide with PVP film. Its sensing properties were investigated by injecting a humid air range of 10.6~32%RH (relative humidity) at room temperature. The surface morphology of the PVP film was characterized by an atomic force microscope (AFM). The possible humidity sensing mechanism of the proposed sensor was discussed by using absorption spectra. This study showed that the PVP-coated OWG sensor possessed high sensitivity, stability, and rapid response/recovery. Therefore, these observed results demonstrate that the low-cost OWG humidity sensor could be applied in real-time low concentration water vapor monitoring.

Abrin is a cytotoxin with strong lethality, which is a serious threat to human health and public safety, and thus, highly sensitive detection methods are urgently needed. The phage display affibody has two major modules, among which, the affibody fragment, with small molecular weight, high affinity and easy preparation, can be used for the specific recognition of the target, and the phage shell, with numerous protein copies, can be used as a carrier for the massive enrichment of signal molecules, and thus is particularly suitable as a sensitive probe for signal amplification in high-sensitivity biosensors. In this study, with antibody-coated magnetic microspheres as capture probes, Ru(bpy)₃²⁺ and biotin dual-labeled phage display affibodies as the specific signal probes and AuNPs@Ru(bpy)₃²⁺ (Ru(bpy)₃²⁺-coated gold nanoparticles) as the signal amplification nanomaterials, a new electrochemiluminescence (ECL) biosensor with a four-level sandwich structure of “magnetic capture probe-abrin-phage display affibody-AuNPs@Ru(bpy)₃²⁺” was constructed for abrin detection. In this detection mode, AuNPs@Ru(bpy)₃²⁺, a gold nanocomposite prepared rapidly via electrical interaction, contained an extremely high density of signal molecules, and the phage display affibodies with powerful loading capacity were not only labeled with Ru(bpy)₃²⁺, but also enriched with AuNPs@Ru(bpy)₃²⁺ in large amounts. These designs greatly improved the detection capability of the sensor, ultimately achieving the ultra-sensitive detection of abrin. The limit of detection (LOD) was 4.1 fg/mL (3δ/S), and the quantification range was from 5 fg/mL to 5 pg/mL. The sensor had good reproducibility and specificity and performed well in the test of simulated samples. This study expanded the application of affibodies in the field of biosensing and also deeply explored the signal amplification potential of phage display technology, which is of high value for the construction of simple and efficient sensors with high sensitivity.