An ultrasensitive and dual-recognition SERS biosensor based on Fe3O4@Au-Teicoplanin and aptamer functionalized Au@Ag nanoparticles for detection of Staphylococcus aureus

Seizing the Hidden Assassin: Current Detection Strategies for Staphylococcus aureus and Methicillin-Resistant S. aureus

Staphylococcus aureus (S. aureus) is a kind of pathogenic bacteria which can lead to food poisoning, hospital, and community infections. S. aureus and methicillin-resistant S. aureus (MRSA) have become headaches for public health worldwide. Therefore, strengthening the detection of S. aureus and MRSA is a critical step to prevent and control its spread and infection. This review summarized multiple detection methods (electrochemical, optical, and other biosensors) for sensitive and efficient detection of nonresistant and resistant S. aureus. First, we have introduced the principle and methods of detection platform for S. aureus and MRSA. We also contrasted various detection strategies. Finally, the current situation and prospect of S. aureus and MRSA detection in the future are explored in depth, and its development direction of detection methods is also predicted. In this review, we found that although biosensors have shown tremendous brilliance in the field of monitoring, they are currently in the experimental stage. It can be certain that we are very close to entering the commercialization stage. The point-of care testing available to nonprofessionals will become a new direction. We firmly believe that the monitoring system will be more perfect and stable and public life will be healthier and safer.

Portable SERS biosensor based on aptamer-assisted catalytic hairpin assembly signal amplification for ultrasensitive detection of Staphylococcus aureus

Bacteria infections pose a serious threat to public health, and it is urgent to develop facile and accurate detection methods. To meet the important need, a potable and high-sensitive surface enhanced Raman scattering (SERS) biosensor based on aptamer recognition and catalytic hairpin assembly (CHA) signal amplification was proposed for point-of-care detection of Staphylococcus aureus (S. aureus). The SERS biosensor contains three parts: recognition probes, SERS sensing chip, and SERS tags. The feasibility of the strategy was verified by gel electrophoresis, and the one-step test route was optimized. The bacteria SERS biosensor has a good linear relationship ranging from 10 to 107 CFU mL-1 with high sensitivity low to 5 CFU mL-1, and shows excellent specificity, uniformity, and repeatability on S. aureus identification and enumeration, which can distinguish S. aureus from other bacteria. The SERS biosensor shows a good recovery rate (95.73 %-109.65 %) for testing S. aureus spiked in milk, and has good practicability for detecting S. aureus infected mouse wound, which provides a facile and reliable approach for detection of trace bacteria in the real samples.

Click preparation of triazole-bridged teicoplanin-bound chiral stationary phases for efficient separating amino acid enantiomers

Enantioseparation of amino acids is considered as a challenging task due to the extreme structural similarity of their enantiomers. Herein, teicoplanin was modified with different chemical equivalents of azide groups and attached to silica particles by employing Click Chemistry for resolution of chiral amino acids for the first time. Interestingly, teicoplanin modified with 5-fold the chemical equivalent of azide groups (TK-2 CSP) exhibited superior amino acid separation ability compared to two other columns: one modified with only 1-fold the chemical equivalent of azide groups (TK-1 CSP), and the other modified with excess azide groups (TK-3 CSP). Additionally, the TK-2 CSP exhibited superior enantioselectivity when separating amino acids containing hydrophobic alkyl side chains in comparison to other teicoplanin-based CSPs. The TK-2 CSP column allows the baseline separation of 7 native amino acids. Molecular docking demonstrates that effective enantioseparation arises from distinct patterns of interaction between the host and guest molecules. Moreover, (p-methyl) phenylcarbaminoylated-teicoplanin CSP (TK-4, TK-5 CSP) were prepared by post-modification from TK-1 CSP and TK-2 CSP to isolate Fmoc-modified amino acids. This work explores the impact of various modification methods on the enantioseparation effects of host molecules and paves the way for expanding the potential applications of teicoplanin and macrocyclic glycopeptide molecules.

Nanotechnology improves the detection of bacteria: Recent advances and future perspectives

Nanotechnology has advanced significantly, particularly in biomedicine, showing promise for nanomaterial applications. Bacterial infections pose persistent public health challenges due to the lack of rapid pathogen detection methods, resulting in antibiotic overuse and bacterial resistance, threatening the human microbiome. Nanotechnology offers a solution through nanoparticle-based materials facilitating early bacterial detection and combating resistance. This study explores recent research on nanoparticle development for controlling microbial infections using various nanotechnology-driven detection methods. These approaches include Surface Plasmon Resonance (SPR) Sensors, Surface-Enhanced Raman Scattering (SERS) Sensors, Optoelectronic-based sensors, Bacteriophage-Based Sensors, and nanotechnology-based aptasensors. These technologies provide precise bacteria detection, enabling targeted treatment and infection prevention. Integrating nanoparticles into detection approaches holds promise for enhancing patient outcomes and mitigating harmful bacteria spread in healthcare settings.

Bonding states of gold/silver plasmonic nanostructures and sulfur-containing active biological ingredients in biomedical applications: a review

As one of the most instrumental components in the architecture of advanced nanomedicines, plasmonic nanostructures (mainly gold and silver nanomaterials) have been paid a lot of attention. This type of nanomaterial can absorb light photons with a specific wavelength and generate heat or excited electrons through surface resonance, which is a unique physical property. In innovative biomaterials, a significant number of theranostic (therapeutic and diagnostic) materials are produced through the conjugation of thiol-containing ingredients with gold and silver nanoparticles (Au and Ag NPs). Hence, it is essential to investigate Au/Ag-S interfaces precisely and determine the exact bonding states in the active nanobiomaterials. This study intends to provide useful insights into the interactions between Au/Ag NPs and thiol groups that exist in the structure of biomaterials. In this regard, the modeling of Au/Ag-S bonding in active biological ingredients is precisely reviewed. Then, the physiological stability of Au/Ag-based plasmonic nanobioconjugates in real physiological environments (pharmacokinetics) is discussed. Recent experimental validation and achievements of plasmonic theranostics and radiolabelled nanomaterials based on Au/Ag-S conjugation are also profoundly reviewed. This study will also help researchers working on biosensors in which plasmonic devices deal with the thiol-containing biomaterials (e.g., antibodies) inside blood serum and living cells.

Surface-Enhanced Raman Spectroscopy Sensor Integrated with Ag@ZIF-8@Au Core-Shell-Shell Nanowire Membrane for Enrichment, Ultrasensitive Detection, and Inactivation of Bacteria in the Environment

A core-shell-shell sandwich material is developed with silver nanowires as the core, ZIF-8 as an inner shell, and gold nanoparticles as the outer shell, namely, Ag@ZIF-8@Au nanowires (AZA-NW). Then, the synthesized AZA-NW is transformed into a surface-enhanced Raman spectroscopy (SERS) sensor (named M-AZA) by the vacuum filtration method and used to enrich, detect, and inactivate traces of bacteria in the environment. The M-AZA sensor has three main functions: (1) trace bacteria are effectively enriched, with an enrichment efficiency of 91.4%; (2) ultrasensitive detection of trace bacteria is realized, with a minimum detectable concentration of 1 × 101 CFU/mL; (3) bacteria are effectively killed up to 92.4%. The shell thickness of ZIF-8 (5-75 nm) is controlled by adjusting the synthesis conditions. At an optimum shell thickness of 15 nm, the effect of gold nanoparticles and ZIF-8 shell on the sensor's stability, SERS activity, and antibacterial performance is investigated. The simulation of the SERS sensor using the finite difference time domain (FDTD) method is consistent with the experimental results, theoretically demonstrating the role of the gold nanoparticles and the ZIF-8 shell. The sensor also shows excellent stability, safety, and generalizability. The campus water sample is then tested on-site by the M-AZA SERS sensor, indicating its potential for practical applications.

"Magnet" Based on Activated Silver Nanoparticles Adsorbed Bacteria to Predict Refractory Apical Periodontitis Via Surface-Enhanced Raman Scattering

Refractory apical periodontitis (RAP) is an endodontic apical inflammatory disease caused by Enterococcus faecalis (E. faecalis). Bacterial detection using surface-enhanced Raman scattering (SERS) technology is a hot research topic, but the specific and direct detection of oral bacteria is a challenge, especially in real clinical samples. In this paper, we develop a novel SERS-based green platform for label-free detection of oral bacteria. The platform was built on silver nanoparticles with a two-step enhancement way using NaBH4 and sodium (Na+) to form "hot spots," which resulted in an enhanced SERS fingerprint of E. faecalis with fast, quantitative, lower-limit, reproducibility, and stability. In combination with machine learning, four different oral bacteria (E. faecalis, Porphyromonas gingivalis, Streptococcus mutans, and Escherichia coli) could be intelligently distinguished. The unlabeled detection method emphasized the specificity of E. faecalis in simulated saliva, serum, and even real samples from patients with clinical root periapical disease. In addition, the assay has been shown to be environmentally friendly and without secondary contamination through antimicrobial assays. The proposed label-free, rapid, safe, and green SERS detection strategy for oral bacteria provided an innovative solution for the early diagnosis and prevention of RAP and other perioral diseases.

Nanomaterial surface modification toolkit: Principles, components, recipes, and applications

Surface-functionalized nanostructures are at the forefront of biotechnology, providing new opportunities for biosensors, drug delivery, therapy, and bioimaging applications. The modification of nanostructures significantly impacts the performance and success of various applications by enabling selective and precise targeting. This review elucidates widely practiced surface modification strategies, including click chemistry, cross-coupling, silanization, aldehyde linkers, active ester chemistry, maleimide chemistry, epoxy linkers, and other protein and DNA-based methodologies. We also delve into the application-focused landscape of the nano-bio interface, emphasizing four key domains: therapeutics, biosensing, environmental monitoring, and point-of-care technologies, by highlighting prominent studies. The insights presented herein pave the way for further innovations at the intersection of nanotechnology and biotechnology, providing a useful handbook for beginners and professionals. The review draws on various sources, including the latest research articles (2018-2023), to provide a comprehensive overview of the field.

Staphylococcus aureus - Review on potential targets for sensors development

Staphylococcus aureus (S. aureus) is accountable for a wide variety of clinical disease with a high rate of morbidity and mortality around the globe. It has a leading place into the ESKAPE group that includes six pathogens and exhibit multidrug resistance and are the major cause of healthcare associated infections: Enterococcus faecium, S. aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. A critical overview regarding the development of sensors for both S. aureus and his, more dangerous alter ego, Methicillin-resistant S. aureus (MRSA) was presented focusing on the bacteria targets starting with the detection of the whole cell, up to specific wall components, toxins or other virulence factors. The literature data was systematically assessed having in sight the design of the sensing platforms, the analytical performances, and possible courses of action to be implemented in real practice as point-of-care (POC) devices. Moreover, a distinct section was dedicated to commercially available devices and out of the box approaches, namely the use of bacteriophages as an alternative to antimicrobial therapy and as sensors modifiers. The reviewed sensors and devices were discussed in terms of their suitability for different biosensing applications, in early screening of contamination regarding food analysis, environmental monitoring and in clinical diagnosis.

Recent Progress of Surface-Enhanced Raman Spectroscopy for Bacteria Detection

There are various pathogenic bacteria in the surrounding living environment, which not only pose a great threat to human health but also bring huge losses to economic development. Conventional methods for bacteria detection are usually time-consuming, complicated and labor-intensive, and cannot meet the growing demands for on-site and rapid analyses. Sensitive, rapid and effective methods for pathogenic bacteria detection are necessary for environmental monitoring, food safety and infectious bacteria diagnosis. Recently, benefiting from its advantages of rapidity and high sensitivity, surface-enhanced Raman spectroscopy (SERS) has attracted significant attention in the field of bacteria detection and identification as well as drug susceptibility testing. Here, we comprehensively reviewed the latest advances in SERS technology in the field of bacteria analysis. Firstly, the mechanism of SERS detection and the fabrication of the SERS substrate were briefly introduced. Secondly, the label-free SERS applied for the identification of bacteria species was summarized in detail. Thirdly, various SERS tags for the high-sensitivity detection of bacteria were also discussed. Moreover, we emphasized the application prospects of microfluidic SERS chips in antimicrobial susceptibility testing (AST). In the end, we gave an outlook on the future development and trends of SERS in point-of-care diagnoses of bacterial infections.

Integration of three non-interfering SERS probes combined with ConA-functionalized magnetic nanoparticles for extraction and detection of multiple foodborne pathogens

A sandwich-structured SERS biosensor has been constructed for simultaneous detection of multiple pathogenic bacteria, consisting of non-interfering SERS probes for bacterial labeling and ConA-functionalizd magnetic nanoparticles for bacteria extraction. A the preparation method of PP3 SERS probe with high Raman activity is reported for the first time. Since the PP3 SERS probe has a very strong Raman peak at 2081 cm^-1 in the "Raman silent region," the mixed SERS probe formed with MP1 and DP2 can meet the needs of multiple foodborne pathogen detection. Significantly, S. aureus, E. coli, and P. aeruginosa can be successfully extracted upon external magnetic field, and the limit of detection (LOD) is 1 CFU‧mL^-1, lower than that of the congeneric detectors. This work paves a new way for the construction of a novel detector and absorbent for different bacteria in complex samples by using SERS probe.

LSPR Tunable Ag@PDMS SERS Substrate for High Sensitivity and Uniformity Detection of Dye Molecules

At present, the use of efficient and cost-effective methods to construct plasmonic surface-enhanced Raman scattering (SERS) substrates of high sensitivity, uniformity and reproducibility is still crucial to satisfy the practical application of SERS technology. In this paper, a localized surface plasmonic resonance (LSPR) tunable flexible Ag@PDMS substrate was successfully constructed by the low-cost bio-template-stripping method and magnetron sputtering technology. The theory proves that the local electromagnetic field enhancement and "hot spot" distribution is adjustable by modifying the size of the optical cavity unit in the periodicity nanocavity array structure. Experimentally, using rhodamine 6G (R6G) as the target analyte, the SERS performance of optimal Ag@PDMS substrate (Ag film thickness for 315 nm) was researched in detail, which the minimum detection limit was 10^-11 M and the enhancement factor was calculated as 8.03 × 10⁸, indicating its high sensitivity. The relative standard deviation (RSD) was calculated as 10.38%, showing that the prepared substrate had excellent electromagnetic field enhancement uniformity. At last, the trace detection of Crystal violet (CV, LOD = 10^-9 M) and the simultaneous detection of three common dyes (R6G, CV and Methylene blue (MB) mixture) were also realized. This result suggests that the SERS substrate has a good application prospect in the quantitative and qualitative detection of dye molecules.

Toward intelligent food packaging of biosensor and film substrate for monitoring foodborne microorganisms: A review of recent advancements

Microorganisms in food do harms to human. They can cause serious adverse reactions and sometimes even death. So it is an urgent matter to find an effective method to control them. The research of intelligent- biosensor packaging is in the ascendant in recent years, which is mainly promoted by reflecting on food safety and reducing resource waste. Intelligent biosensor-packaging is an instant and efficient intelligent packaging technology, which can directly and scientifically manifest the quality of food without complex operation. In this review, the purposes of providing relevant information on intelligent biosensor-packaging are reviewed, such as types of biosensors for monitoring foodborne microorganism, the suitable material for intelligent biosensor-packaging and design and fabrication of intelligent biosensor-packaging. The potential of intelligent biosensor-packaging in the detection of foodborne microorganisms is emphasized. The challenges and directions of the intelligent biosensor-packaging in the detection of foodborne pathogens are discussed. With the development of science and technology in the future, the intelligent biosensor-packaging should be commercialized in a real sense. And it is expected that commercial products can be manufactured in the future, which will provide a far-reaching approach in food safety and food prevention. HighlightsSeveral biosensors are suitable for the detection of food microorganisms.Plastic polymer is an excellent choice for the construction of intelligent biosensor packaging.Design and fabrication can lay the foundation for intelligent-biosensor packaging.Intelligent biosensor-packaging can realize fast and real-time detection of microorganisms in food.