Localized Surface Plasmon Resonance (LSPR)-Coupled Fiber-Optic Nanoprobe for the Detection of Protein Biomarkers

Metal Nanoparticle-Based Biosensors for the Early Diagnosis of Infectious Diseases Caused by ESKAPE Pathogens in the Fight against the Antimicrobial-Resistance Crisis

The species included in the ESKAPE group (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and the genus Enterobacter) have a high capacity to develop antimicrobial resistance (AMR), a health problem that is already among the leading causes of death and could kill 10 million people a year by 2050. The generation of new potentially therapeutic molecules has been insufficient to combat the AMR "crisis", and the World Health Organization (WHO) has stated that it will seek to promote the development of rapid diagnostic strategies. The physicochemical properties of metallic nanoparticles (MNPs) have made it possible to design biosensors capable of identifying low concentrations of ESKAPE bacteria in the short term; other systems identify antimicrobial susceptibility, and some have been designed with dual activity in situ (bacterial detection and antimicrobial activity), which suggests that, in the near future, multifunctional biosensors could exist based on MNPs capable of quickly identifying bacterial pathogens in clinical niches might become commercially available. This review focuses on the use of MNP-based systems for the rapid and accurate identification of clinically important bacterial pathogens, exhibiting the necessity for exhaustive research to achieve these objectives. This review focuses on the use of metal nanoparticle-based systems for the rapid and accurate identification of clinically important bacterial pathogens.

Simply and cost-effectively fabricated AuNP-based fusion spliced transmissive optical fiber LSPR probes

The transmissive optical fiber localized surface plasmon resonance (LSPR) sensor has become an effective tool in refractive index sensing because of its compact structure, high sensitivity and strong designability. However, its special structure with the sensing region in the middle of the optical fiber leads to the shortcomings of difficult preparation and poor reproducibility, which greatly restricts its application scopes. In order to solve such problem, we design gold nanoparticle (AuNP)-based fusion spliced transmissive optical fiber LSPR probes, which are fabricated via the fusion splicing between the surface modified combination tapered optical fiber and another multimode quartz optical fiber but are totally different from other fabrications of the reported transmissive optical fiber LSPR probes. The fiber probe fabrication is rather simple and cost-effective, only relying on the procedures of combination tapered optical fiber preparation, surface modification and probe fusion splicing, and except for the probe fusion splicing, the other procedures can be mass prepared thus maintaining high efficiency and good reproducibility in fiber probe fabrications. Moreover, according to the experimental verifications, the proposed fiber probes can reach rather high sensitivity in refractive index sensing with high accuracy and good stability in both static and dynamic detecting modes. Therefore, the AuNP-based fusion spliced transmissive optical fiber LSPR probe is a preferred solution for refractive index sensing and can be widely used in various applications.

A Review: Evolution and Diversity of Optical Fibre Plasmonic Sensors

The purpose of this review is to bring to the attention of the wider research community how two quite different optical sensory techniques were integrated resulting in a sensor device of exceptional sensitivity with wide ranging capability. Both authors have collaborated over a 20 year period, each researching initially surface plasmon resonance (SPR) and optical fibre Bragg grating devices. Our individual research, funded in part by EPSRC and industry into these two areas, converged, resulting in a device that combined the ultra-sensitive working platform of SPR behavior with that of fibre Bragg grating development, which provided a simple method for SPR excitation. During this period, they developed a new approach to the fabrication of nano-structured metal coatings for plasmonic devices and demonstrated on fibre optic platform, which has created an ultra-sensitive optical sensing platform. Both authors believe that the convergence of these two areas will create opportunities in detection and sensing yet to be realised. Furthermore, giving the reader "sign-post" research articles to help to construct models to design sensors and to understand their experimental results.

Surface Plasmon Resonance or Biocompatibility-Key Properties for Determining the Applicability of Noble Metal Nanoparticles

Metal and in particular noble metal nanoparticles represent a very special class of materials which can be applied as prepared or as composite materials. In most of the cases, two main properties are exploited in a vast number of publications: biocompatibility and surface plasmon resonance (SPR). For instance, these two important properties are exploitable in plasmonic diagnostics, bioactive glasses/glass ceramics and catalysis. The most frequently applied noble metal nanoparticle that is universally applicable in all the previously mentioned research areas is gold, although in the case of bioactive glasses/glass ceramics, silver and copper nanoparticles are more frequently applied. The composite partners/supports/matrix/scaffolds for these nanoparticles can vary depending on the chosen application (biopolymers, semiconductor-based composites: TiO₂, WO₃, Bi₂WO₆, biomaterials: SiO₂ or P₂O₅-based glasses and glass ceramics, polymers: polyvinyl alcohol (PVA), Gelatin, polyethylene glycol (PEG), polylactic acid (PLA), etc.). The scientific works on these materials' applicability and the development of new approaches will be targeted in the present review, focusing in several cases on the functioning mechanism and on the role of the noble metal.