AuNPs for identification of molecular signatures of resistance

Progress in the role of nanoparticles in the diagnosis and treatment of bone and joint tuberculosis

Bone and joint tuberculosis (BJTB), caused by Mycobacterium tuberculosis (MTB), is a prevalent form of extrapulmonary tuberculosis that poses significant challenges to global public health due to difficulties in early diagnosis, prolonged treatment cycles, and drug resistance. Recent advancements in nanotechnology have introduced novel solutions for the early detection and precise treatment of BJTB, leveraging unique physicochemical properties such as high specific surface area, targeted delivery capabilities, sustained drug release, and excellent biocompatibility. In diagnostic applications, nanomaterials markedly enhance the sensitivity and accuracy of detection methods while reducing testing time. These technologies are adaptable to resource-limited settings, enabling earlier patient intervention and mitigating disease progression risk. In therapeutic applications, nanomaterials prolong drug retention in bone tissue through targeted delivery, thereby decreasing medication frequency and minimizing toxic side effects, which significantly improves treatment efficacy. Despite substantial progress, further research is required to address long-term safety concerns, broaden clinical applicability, and evaluate performance under complex pathological conditions. This review summarizes recent advancements in nanomaterials for diagnosing and treating BJTB and identifies key areas for future research, laying the groundwork for advancing precision medicine and personalized treatments.

Nucleic Acid Lateral Flow Assay Implemented with Isothermal Gene Amplification of SARS-CoV-2 RNA

We developed a rapid and sensitive diagnostic platform that integrates isothermal viral gene amplification with a nucleic acid lateral flow assay (NALFA) to detect SARS-CoV-2 RNA. Isothermal gene amplification was performed by combining reverse transcription of viral RNA with recombinase polymerase amplification (RPA). In our diagnostic platform, DNA primers for the RPA reaction were modified by appending DNA tails, enabling the synthesis of tailed amplicon DNAs. These tailed amplicon DNAs were subsequently annealed to the complementary capture DNA probe affixed to the lateral flow strip during the NALFA of the reaction samples. The other side of each amplicon DNA tail was annealed to the reporter probe DNA conjugated with gold nanoparticles to visually detect the test line in the strip. This diagnostic platform reduces the time required to obtain readouts to within 1 h and can detect viral RNA concentrations as low as 3.1 cp/μL. Furthermore, when applied to nasopharyngeal clinical samples, our NALFA diagnostic platform yielded highly reliable molecular diagnostic readouts that were 100% consistent with the results of conventional RT-qPCR.

Nanotechnology Approaches for Rapid Detection and Theranostics of Antimicrobial Resistant Bacterial Infections

As declared by WHO, antimicrobial resistance (AMR) is a high priority issue with a pressing need to develop impactful technologies to curb it. The rampant and inappropriate use of antibiotics due to the lack of adequate and timely diagnosis is a leading cause behind AMR evolution. Unfortunately, populations with poor economic status and those residing in densely populated areas are the most affected ones, frequently leading to emergence of AMR pathogens. Classical approaches for AMR diagnostics like phenotypic methods, biochemical assays, and molecular techniques are cumbersome and resource-intensive and involve a long turnaround time to yield confirmatory results. In contrast, recent emergence of nanotechnology-assisted approaches helps to overcome challenges in classical approaches and offer simpler, more sensitive, faster, and more affordable solutions for AMR diagnostics. Nanomaterial platforms (metallic, quantum-dot, carbon-based, upconversion, etc.), nanoparticle-based rapid point-of-care platforms, nano-biosensors (optical, mechanical, electrochemical), microfluidic-assisted devices, and importantly, nanotheranostic devices for diagnostics with treatment of AMR infections are examples of rapidly growing nanotechnology approaches used for AMR management. This review comprehensively summarizes the past 10 years of research progress on nanotechnology approaches for AMR diagnostics and for estimating antimicrobial susceptibility against commonly used antibiotics. This review also highlights several bottlenecks in nanotechnology approaches that need to be addressed prior to considering their translation to clinics.

Environmentally Safe Biosynthesis of Gold Nanoparticles Using Plant Water Extracts

Due to their simplicity of synthesis, stability, and functionalization, low toxicity, and ease of detection, gold nanoparticles (AuNPs) are a natural choice for biomedical applications. AuNPs’ unique optoelectronic features have subsequently been investigated and used in high-tech applications such as organic photovoltaics, sensory probes, therapeutic agents, the administration of drugs in biological and medical applications, electronic devices, catalysis, etc. Researchers have demonstrated the biosynthesis of AuNPs using plants. The present study evaluates 109 plant species used in the traditional medicine of Middle East countries as new sources of AuNPs in a wide variety of laboratory environments. In this study, dried samples of bark, bulb, flower, fruit, gum, leaf, petiole, rhizome, root, seed, stamen, and above-ground parts were evaluated in water extracts. About 117 plant parts were screened from 109 species in 54 plant families, with 102 extracts demonstrating a bioreduction of Au³⁺ to Au⁰, revealing 37 new plant species in this regard. The color change of biosynthesized AuNPs to gray, violet, or red was confirmed by UV-Visible spectroscopy, TEM, FSEM, DLS, and EDAX of six plants. In this study, AuNPs of various sizes were measured from 27 to 107 nm. This study also includes an evaluation of the potency of traditional East Asian medicinal plants used in this biosynthesis of AuNPs. An environmentally safe procedure such as this could act as a foundation for cosmetic industries whose quality assessment systems give a high priority to non-chemically synthesized products. It is crucial that future optimizations are adequately documented to scale up the described process.

Diagnosing Antibiotic Resistance Using Nucleic Acid Enzymes and Gold Nanoparticles

The rapid and accurate detection of antimicrobial resistance is critical to limiting the spread of infections and delivering effective treatments. Here, we developed a rapid, sensitive, and simple colorimetric nanodiagnostic platform to identify disease-causing pathogens and their associated antibiotic resistance genes within 2 h. The platform can detect bacteria from different biological samples (i.e., blood, wound swabs) with or without culturing. We validated the multicomponent nucleic acid enzyme-gold nanoparticle (MNAzyme-GNP) platform by screening patients with central line associated bloodstream infections and achieved a clinical sensitivity and specificity of 86% and 100%, respectively. We detected antibiotic resistance in methicillin-resistant Staphylococcus aureus (MRSA) in patient swabs with 90% clinical sensitivity and 95% clinical specificity. Finally, we identified mecA resistance genes in uncultured nasal, groin, axilla, and wound swabs from patients with 90% clinical sensitivity and 95% clinical specificity. The simplicity and versatility for detecting bacteria and antibiotic resistance markers make our platform attractive for the broad screening of microbial pathogens.

Rapid One-Pot Detection of SARS-CoV-2 Based on a Lateral Flow Assay in Clinical Samples

Rapid tests for pathogen identification and spread assessment are critical for infectious disease control and prevention. The control of viral outbreaks requires a nucleic acid diagnostic test that is sensitive and simple and delivers fast and reliable results. Here, we report a one-pot direct reverse transcript loop-mediated isothermal amplification (RT-LAMP) assay of SARS-CoV-2 based on a lateral flow assay in clinical samples. The entire contiguous sample-to-answer workflow takes less than 40 min from a clinical swab sample to a diagnostic result without professional instruments and technicians. The assay achieved an accuracy of 100% in 12 synthetic and 12 clinical samples compared to the data from PCR-based assays. We anticipate that our method will provide a universal platform for rapid and point-of-care detection of emerging infectious diseases.

Colorimetric-based detection of Ureaplasma urealyticum using gold nanoparticles

Ureaplasma urealyticum (uu) is one of the most common agents of urogenital infections and is associated with complications such as infertility, spontaneous abortion and other sexually transmitted diseases. Here, a DNA sensor based on oligonucleotide target-specific gold nanoparticles (AuNPs) was developed, in which the dispersed and aggregated states of oligonucleotide-functionalised AuNPs were optimised for the colorimetric detection of a polymerase chain reaction (PCR) amplicon of U. urealyticum DNA. A non-cross-linking approach utilising a single Au-nanoprobe specific of the urease gene was utilised and the effect of a PCR product concentration gradient evaluated. Results from both visual and spectral analyses showed that target-Au-nanoprobe hybrids were stable against aggregation after adding the inducer. Furthermore, when a non-target PCR product was used, the peak position shifted and salt-induced aggregation occurred. The assay's limit of detection of the assay was 10 ng with a dynamic range of 10-60 ng. This procedure provides a rapid, facile and low-cost detection format, compared to methods currently used for the identification of U. urealyticum.

Plant-based gold nanoparticles; a comprehensive review of the decade-long research on synthesis, mechanistic aspects and diverse applications

The worldwide focus on research in the field of green nanotechnology has resulted in the environmentally and biologically safe applications of a diversity of nanomaterials. Nanotechnology, in general, implies the production of nanoparticles having different but regular shapes, sizes, and properties. A lot of studies have been conducted on the synthesis of metal nanoparticles through biological, chemical, and physical methods. Owing to its safety, both environmental and in vivo, as well as the ease of synthesis, biogenic routes especially the plant-based synthesis of metal nanoparticles has been preferred as the best strategy. Among the metal nanoparticles, gold nanoparticles are recognized as the most potent, biocompatible and environment-friendly. A decade of research work has attempted the production of gold nanoparticles mediated by different parts of various plants. Further, these nanoparticles have been engineered through modification in the sizes and shapes for attaining enhanced activity and optimal performance in many different applications including biomedical, antimicrobial, diagnostics and environmental applications. This article reviews the fabrication strategies for gold nanoparticles via plant-based routes and highlights the diversity of the applications of these materials in bio-nanotechnology. The review article also highlights the recent developments in the synthesis and optical properties of gold nanoparticles.

Recent advances in the treatment of pathogenic infections using antibiotics and nano-drug delivery vehicles

The worldwide misuse of antibiotics and the subsequent rise of multidrug-resistant pathogenic bacteria have prompted a paradigm shift in the established view of antibiotic and bacterial-human relations. The clinical failures of conventional antibiotic therapies are associated with lengthy detection methods, poor penetration at infection sites, disruption of indigenous microflora and high potential for mutational resistance. One of the most promising strategies to improve the efficacy of antibiotics is to complex them with micro or nano delivery materials. Such materials/vehicles can shield antibiotics from enzyme deactivation, increasing the therapeutic effectiveness of the drug. Alternatively, drug-free nanomaterials that do not kill the pathogen but target virulent factors such as adhesins, toxins, or secretory systems can be used to minimize resistance and infection severity. The main objective of this review is to examine the potential of the aforementioned materials in the detection and treatment of antibiotic-resistant pathogenic organisms.

Triplex-hybridizing bioconjugated gold nanoparticles for specific Y-chromosome sequence targeting of bull spermatozoa

Gold nanoparticles (AuNPs) are widely used in biomedical applications for drug targeting and bioimaging. This often neccesitates their functionalization with biomolecules carrying a defined biological function, yielding gold nanoparticle bioconjugates. The utilization of triplex-forming oligonucleotides (TFOs) as ligands gives access to nanoconjugates as tools for specific DNA-related nanotargeting via triplex hybridization. Since triplex hybridization with nanobioconjugates has to date not been shown on biologically relevant samples, sex-specific sperm marking may be an appropriate model system to demonstrate the opportunities of this targeting method in vitro. In this study, we focused on specific labeling of repetitive target sites enriched on the bovine Y-chromosome using triplex forming oligonucleotides. First, the functionality of a specific locked nucleic acid (LNA) sequence was confirmed on bovine free DNA and on demembranated sperm heads. Thereafter, the influence of AuNPs on triplex hybridization was spectrophotometrically analyzed employing synthetic dsDNA, genomic DNA and demembranated sperm heads. Results from the SPR-peak shift indicate that TFO-AuNP hybridize to bovine gDNA in a qualitative and significant manner. These results confirm successful triplex hybridization on biologically relevant target sites as well as the establishment of a method to use gold nanoparticles as a suitable tool for sex-selective hybridization.

Nano-Strategies to Fight Multidrug Resistant Bacteria-"A Battle of the Titans"

Infectious diseases remain one of the leading causes of morbidity and mortality worldwide. The WHO and CDC have expressed serious concern regarding the continued increase in the development of multidrug resistance among bacteria. Therefore, the antibiotic resistance crisis is one of the most pressing issues in global public health. Associated with the rise in antibiotic resistance is the lack of new antimicrobials. This has triggered initiatives worldwide to develop novel and more effective antimicrobial compounds as well as to develop novel delivery and targeting strategies. Bacteria have developed many ways by which they become resistant to antimicrobials. Among those are enzyme inactivation, decreased cell permeability, target protection, target overproduction, altered target site/enzyme, increased efflux due to over-expression of efflux pumps, among others. Other more complex phenotypes, such as biofilm formation and quorum sensing do not appear as a result of the exposure of bacteria to antibiotics although, it is known that biofilm formation can be induced by antibiotics. These phenotypes are related to tolerance to antibiotics in bacteria. Different strategies, such as the use of nanostructured materials, are being developed to overcome these and other types of resistance. Nanostructured materials can be used to convey antimicrobials, to assist in the delivery of novel drugs or ultimately, possess antimicrobial activity by themselves. Additionally, nanoparticles (e.g., metallic, organic, carbon nanotubes, etc.) may circumvent drug resistance mechanisms in bacteria and, associated with their antimicrobial potential, inhibit biofilm formation or other important processes. Other strategies, including the combined use of plant-based antimicrobials and nanoparticles to overcome toxicity issues, are also being investigated. Coupling nanoparticles and natural-based antimicrobials (or other repurposed compounds) to inhibit the activity of bacterial efflux pumps; formation of biofilms; interference of quorum sensing; and possibly plasmid curing, are just some of the strategies to combat multidrug resistant bacteria. However, the use of nanoparticles still presents a challenge to therapy and much more research is needed in order to overcome this. In this review, we will summarize the current research on nanoparticles and other nanomaterials and how these are or can be applied in the future to fight multidrug resistant bacteria.

Exploitation of microbial forensics and nanotechnology for the monitoring of emerging pathogens

Emerging infectious diseases remain among the leading causes of global mortality. Traditional laboratory diagnostic approaches designed to detect and track infectious disease agents provide a framework for surveillance of bio threats. However, surveillance and outbreak investigations using such time-consuming approaches for early detection of pathogens remain the major pitfall. Hence, reasonable real-time surveillance systems to anticipate threats to public health and environment are critical for identifying specific aetiologies and preventing the global spread of infectious disease. The current review discusses the growing need for monitoring and surveillance of pathogens with the same zeal and approach as adopted by microbial forensics laboratories, and further strengthening it by integrating with the innovative nanotechnology for rapid detection of microbial pathogens. Such innovative diagnostics platforms will help to track pathogens from high risk areas and environment by pre-emptive approach that will minimize damages. The various scenarios with the examples are discussed where the high risk associated human pathogens in particular were successfully detected using various nanotechnology approaches with potential future prospects in the field of microbial forensics.

Allele specific LAMP- gold nanoparticle for characterization of single nucleotide polymorphisms

•

Allele-specific isothermal amplification method (AS-LAMP) for SNP characterization.

•

Use of ssDNA-functionalized gold nanoparticles (AuNPs) for SNP full discrimination.

•

A simple and low-cost strategy to provide fast results in medium throughput settings.

•

AS-LAMP amplification products can be easily interpreted in less than 15 min.

Due to their relevance as disease biomarkers and for diagnostics, screening of single nucleotide polymorphism (SNPs) requires simple and straightforward strategies capable to provide results in medium throughput settings. Suitable approaches relying on isothermal amplification techniques have been evolving to substitute the cumbersome and highly specialized PCR amplification detection schemes. Nonetheless, identification of an individual’s genotype still requires sophisticated equipment and laborious methods.

Here, we present a low-cost and reliable approach based on the allele specific loop-mediated isothermal amplification (AS-LAMP) coupled to ssDNA functionalized gold nanoparticle (Au-nanoprobe) colorimetric sequence discrimination. The Au-nanoprobe integration allows for the colorimetric detection of AS-LAMP amplification product that can be easily interpreted in less than 15 min. We targeted a clinical relevant SNP responsible for lactose intolerance (-13910C/T dbSNP rs#: 4988235) to demonstrate its proof of concept and full potential of this novel approach.

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.

Gold Nanotheranostics: Proof-of-Concept or Clinical Tool?

Nanoparticles have been making their way in biomedical applications and personalized medicine, allowing for the coupling of diagnostics and therapeutics into a single nanomaterial—nanotheranostics. Gold nanoparticles, in particular, have unique features that make them excellent nanomaterials for theranostics, enabling the integration of targeting, imaging and therapeutics in a single platform, with proven applicability in the management of heterogeneous diseases, such as cancer. In this review, we focus on gold nanoparticle-based theranostics at the lab bench, through pre-clinical and clinical stages. With few products facing clinical trials, much remains to be done to effectively assess the real benefits of nanotheranostics at the clinical level. Hence, we also discuss the efforts currently being made to translate nanotheranostics into the market, as well as their commercial impact.

One nanoprobe, two pathogens: gold nanoprobes multiplexing for point-of-care

Background

Gold nanoparticles have been widely employed for biosensing purposes with remarkable efficacy for DNA detection. Amongst the proposed systems, colorimetric strategies based on the remarkable optical properties have provided for simple yet effective sequence discrimination with potential for molecular diagnostics at point of need. These systems may also been used for parallel detection of several targets to provide additional information on diagnostics of pathogens.

Results

For the first time, we demonstrate that a single Au-nanoprobe may provide for detection of two distinct targets (pathogens) allowing colorimetric multi-target detection. We demonstrate this concept by using one single gold-nanoprobe capable to detect members of the Mycobacterium tuberculosis complex and Plasmodium sp., the etiologic agents of tuberculosis and malaria, respectively. Following characterisation, the developed gold-nanoprobe allowed detection of either target in individual samples or in samples containing both DNA species with the same efficacy.

Conclusions

Using one single probe via the non-cross-linking colorimetric methodology it is possible to identify multiple targets in one sample in one reaction. This proof-of-concept approach may easily be integrated into sensing platforms allowing for fast and simple multiplexing of Au-nanoprobe based detection at point-of-need.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-015-0109-1) contains supplementary material, which is available to authorized users.