A universal approach for sensitive and rapid detection of different pathogenic bacteria based on aptasensor-assisted SERS technique

Preparation of berberine hydrochloride-Ag nanoparticle composite antibacterial dressing based on 3D printing technology

In recent years, Ag nanoparticle (Ag NP)-loaded antibacterial dressings have attracted much attention in high-level medical dressings. However, the high cytotoxicity of Ag NP has always been a problem. In this paper, we examined the improvement of antibacterial activity of berberine hydrochloride (BBR) with Ag NP, the results showed that the combined use of BBR and Ag NP can effectively reduce the dosage of Ag NP while ensuring the inhibition of bacterial growth, thus an intermediate layer dressing containing combined drugs were prepared. At the same time, the top dressing of polyvinyl alcohol (PVA) solid film and the PVA bottom dressings with three kinds of leakage structures were prepared by 3D printing technology. Three kinds of PVA bottom dressings showed high quality consistency, and the greater the number of leak holes, the higher the porosity value of the dressing, while the swelling ratio value of the bottom layer dressing with three holes was the lowest. Finally, three types of BBR-Ag NP composite antibacterial dressings (3D-BBR-Ag NP) can be obtained by self-assembling of the top dressing, the intermediate layer dressing, and the bottom dressings with three kinds of leakage structures. The cumulative drug release results showed that dressing with more holes had a faster drug release rate compared to the other two ones with fewer leakage holes. Besides, five drug release kinetic models were used to investigate the cumulative BBR release profiles for three types of 3D-BBR-Ag NP. And the three types of composite dressings showed strong antibacterial activity after 6 h of cultivation with staphylococcus aureus. The study showed that the antibacterial activity of the self-assembled dressing prepared by combination of BBR with Ag NP can be improved, and the drug release rate of the hydrogel dressing can be flexibly controlled through 3D printing technology.

Key steps for improving bacterial SERS signals in complex samples: Separation, recognition, detection, and analysis

Rapid and reliable detection of pathogenic bacteria is absolutely essential for research in environmental science, food quality, and medical diagnostics. Surface-enhanced Raman spectroscopy (SERS), as an emerging spectroscopic technique, has the advantages of high sensitivity, good selectivity, rapid detection speed, and portable operation, which has been broadly used in the detection of pathogenic bacteria in different kinds of complex samples. However, the SERS detection method is also challenging in dealing with the detection difficulties of bacterial samples in complex matrices, such as interference from complex matrices, confusion of similar bacteria, and complexity of data processing. Therefore, researchers have developed some technologies to assist in SERS detection of bacteria, including both the front-end process of obtaining bacterial sample data and the back-end data processing process. The review summarizes the key steps for improving bacterial SERS signals in complex samples: separation, recognition, detection, and analysis, highlighting the principles of each step and the key roles for SERS pathogenic bacteria analysis, and the interconnectivity between each step. In addition, the current challenges in the practical application of SERS technology and the development trends are discussed. The purpose of this review is to deepen researchers' understanding of the various stages of using SERS technology to detect bacteria in complex sample matrices, and help them find new breakthroughs in different stages to facilitate the detection and control of bacteria in complex samples.

Novel Digital SERS-Microfluidic Chip for Rapid and Accurate Quantification of Microorganisms

In this work, we present a simple and novel digital surface-enhanced Raman spectroscopy (SERS)-microfluidic chip designed for the rapid and accurate quantitative detection of microorganisms. The chip employs a high-density inverted pyramid microcavity (IPM) array to separate and isolate microbial samples. The presence or absence of target microorganisms is determined by scanning the IPM array using SERS and identifying the characteristic Raman bands. This approach allows for the "digitization" of the SERS response of each IPM, enabling quantification through the application of mathematical statistical techniques. Significantly, precise quantitative detection of yeast was achieved within a concentration range of 106-109 cells/mL, with the maximum relative standard deviation from the concentration calibrated by the cultivation method being 5.6%. This innovative approach efficiently addresses the issue of irregularities in SERS quantitative detection, which arises due to fluctuations in SERS intensity and poor reproducibility. We strongly believe that this digital SERS-microfluidic chip holds immense potential for diverse applications in the rapid detection of various microorganisms, including pathogenic bacteria and viruses.