Ultrasensitive chemiluminescent immunoassay of Salmonella with silver enhancement of nanogold labels

Sliding Microneedle - Lateral flow immunoassay strip device for highly sensitive biomarker detection in interstitial fluid

Diabetes is a chronic disease with significant complications, necessitating regular treatment and checkups, which can be costly and time-consuming for patients. To address this, we developed the Sliding Microneedle (MN)-Lateral flow immunoassay strip (LFIAs) device that combines the advantages of MNs and LFIAs to detect IL-6, an independent biomarker for diabetes complications. This device offers rapid and highly sensitive detection of IL-6 by extracting interstitial fluid (ISF) through MNs and transferring it to LFIAs. The stainless MN, embedded in the 3D-printed Sliding MN-LFIAs device, was inserted into the skin at a 20° angle, minimizing blood contamination risk. With a filter paper attached to the MN surface, the device collected 4.65 ± 0.05 μL of ISF containing IL-6 within 90 s. The ISF was then transferred to the LFIAs using a running buffer. After a 15-min reaction, silver enhancement (SE) treatment was applied, allowing for the highly sensitive and specific detection of IL-6 at 102 pg/mL concentrations. The Sliding MN-LFIAs device successfully distinguished between normal and diabetic rat models, demonstrating its potential as an effective tool for detecting diabetes complications quickly and affordably.

Quenching of Luminol Fluorescence at Nano-Bio Interface: Towards the Development of an Efficient Energy Transfer System

Surface modified colloidal gold (Au) and silver (Ag) nanoparticles (NPs) were used as efficient quenchers of luminol (LH₂) fluorescence either in homogeneous aqueous medium or its noncovalent assembly with bovine serum albumin (BSA). The mechanism as well as the extent of fluorescence quenching was found to be strongly dependent on the nature of the nanoparticles. While simple static type fluorescence quenching mechanism was perceived with AuNP, a more complex protocol involving quenching sphere model was envisaged for AgNP quenching. Nevertheless, the magnitude of Stern-Volmer (SV) quenching constant (K_SV ~ 10⁸-10¹⁰ M^-1) was calculated to be ca. 10⁴ times more for surface quoted NPs in comparison with BSA-NP bioconjugates system. On the other hand, a highly efficient (E ≈ 95%) energy transfer (ET) process was predicted for LH₂ captured in the hydrophobic assembly with BSA in presence of AgNP as an acceptor. The ET efficiency is critically dependent on the concentration of BSA and nicely correlated with the extent of NP surface coverage. However, fluorescence quenching on AuNP surface is relatively less responsive towards protein concentration, primarily due to the difference in surface activity as well as the mode of interaction of the protein with NPs. Graphical Abstract Energy transfer from excited luminol to metal nanoparticles is strongly modulated in presence of serum albumins.

Detecting Biothreat Agents: From Current Diagnostics to Developing Sensor Technologies

Although a fundamental understanding of the pathogenicity of most biothreat agents has been elucidated and available treatments have increased substantially over the past decades, they still represent a significant public health threat in this age of (bio)terrorism, indiscriminate warfare, pollution, climate change, unchecked population growth, and globalization. The key step to almost all prevention, protection, prophylaxis, post-exposure treatment, and mitigation of any bioagent is early detection. Here, we review available methods for detecting bioagents including pathogenic bacteria and viruses along with their toxins. An introduction placing this subject in the historical context of previous naturally occurring outbreaks and efforts to weaponize selected agents is first provided along with definitions and relevant considerations. An overview of the detection technologies that find use in this endeavor along with how they provide data or transduce signal within a sensing configuration follows. Current "gold" standards for biothreat detection/diagnostics along with a listing of relevant FDA approved in vitro diagnostic devices is then discussed to provide an overview of the current state of the art. Given the 2014 outbreak of Ebola virus in Western Africa and the recent 2016 spread of Zika virus in the Americas, discussion of what constitutes a public health emergency and how new in vitro diagnostic devices are authorized for emergency use in the U.S. are also included. The majority of the Review is then subdivided around the sensing of bacterial, viral, and toxin biothreats with each including an overview of the major agents in that class, a detailed cross-section of different sensing methods in development based on assay format or analytical technique, and some discussion of related microfluidic lab-on-a-chip/point-of-care devices. Finally, an outlook is given on how this field will develop from the perspective of the biosensing technology itself and the new emerging threats they may face.

Advanced Nanobiomaterials: Vaccines, Diagnosis and Treatment of Infectious Diseases

The use of nanoparticles has contributed to many advances due to their important properties such as, size, shape or biocompatibility. The use of nanotechnology in medicine has great potential, especially in medical microbiology. Promising data show the possibility of shaping immune responses and fighting severe infections using synthetic materials. Different studies have suggested that the addition of synthetic nanoparticles in vaccines and immunotherapy will have a great impact on public health. On the other hand, antibiotic resistance is one of the major concerns worldwide; a recent report of the World Health Organization (WHO) states that antibiotic resistance could cause 300 million deaths by 2050. Nanomedicine offers an innovative tool for combating the high rates of resistance that we are fighting nowadays, by the development of both alternative therapeutic and prophylaxis approaches and also novel diagnosis methods. Early detection of infectious diseases is the key to a successful treatment and the new developed applications based on nanotechnology offer an increased sensibility and efficiency of the diagnosis. The aim of this review is to reveal and discuss the main advances made on the science of nanomaterials for the prevention, diagnosis and treatment of infectious diseases. Highlighting innovative approaches utilized to: (i) increasing the efficiency of vaccines; (ii) obtaining shuttle systems that require lower antibiotic concentrations; (iii) developing coating devices that inhibit microbial colonization and biofilm formation.

Exploitation of Nanotechnology for the Monitoring of Waterborne Pathogens: State-of-the-Art and Future Research Priorities

Contaminated drinking water is one of the most important environmental contributors to the human disease burden. Monitoring of water for the presence of pathogens is an essential part of ensuring drinking water safety. In order to assess water quality it is essential to have methods available to sample and detect the type, level and viability of pathogens in water which are effective, cheap, quick, sensitive, and where possible high throughput. Nanotechnology has the potential to drastically improve the monitoring of waterborne pathogens when compared to conventional approaches. To date, there have been no reviews that outline the applications of nanotechnology in this area despite increasing exploitation of nanotechnology for this purpose. This review is therefore the first overview of the state-of-the-art in the application of nanotechnology to waterborne pathogen sampling and detection schemes. Research in this field has been centered on the use of engineered nanomaterials. The effectiveness and limitations of nanomaterial-based approaches is outlined. A future outlook of the advances that are likely to emerge in this area, as well as recommendations for areas of further research are provided.

Nanobiotechnologies for the detection and reduction of pathogens

Advances in the manipulation of nanomaterials has permitted the development of nanobiotechnology with enhanced sensitivities and improved response times. Low levels of infection of the major pathogens require the need for sensitive detection platforms and the properties of nanomaterials make them suitable for the development of assays with enhanced sensitivity, improved response time and increased portability. Nanobiotechnologies focusing on the key requirements of signal amplification and pre-concentration for the development of sensitive assays for food-borne pathogen detection in food matrices will be described and evaluated. The potential that exists for the use of nanomaterials as antimicrobial agents will also be examined.

Analytical chemiluminescence and bioluminescence: latest achievements and new horizons

Chemiluminescence (CL) and bioluminescence (BL) are the detection techniques of choice for the development of highly sensitive analytical methods, from immunoassays and nucleic acid hybridization assays to whole-cell biosensors. Nevertheless, basic and applied research on CL and BL aimed at further improving their analytical performance is still very active. This research covers diverse and complementary fields, including (among others) enhancing the light emission efficiency of CL systems, the use of nanomaterials to catalyze or enhance CL/BL reactions, the study of BL proteins to elucidate the color modulation mechanism, the discovery of new BL systems, the production of thermostable BL protein mutants with altered emission spectra, the development of BL imaging techniques to expand our understanding of living systems, and the implementation of CL/BL detection in miniaturized analytical devices. In the near future, we expect even greater diffusion of CL/BL-based analytical methods, especially in portable analytical devices intended for applications ranging from environmental analysis to companion diagnostics for personalized medicine.