Antimicrobial peptides: Powerful biorecognition elements to detect bacteria in biosensing technologies

Bacterial infections represent a serious threat in modern medicine. In particular, biofilm treatment in clinical settings is challenging, as biofilms are very resistant to conventional antibiotic therapy and may spread infecting other tissues. To address this problem, biosensing technologies are emerging as a powerful solution to detect and identify bacterial pathogens at the very early stages of the infection, thus allowing rapid and effective treatments before biofilms are formed. Biosensors typically consist of two main parts, a biorecognition moiety that interacts with the target (i.e., bacteria) and a platform that transduces such interaction into a measurable signal. This review will focus on the development of impedimetric biosensors using antimicrobial peptides (AMPs) as biorecognition elements. AMPs belong to the innate immune system of living organisms and are very effective in interacting with bacterial membranes. They offer unique advantages compared to other classical bioreceptor molecules such as enzymes or antibodies. Moreover, impedance-based sensors allow the development of label-free, rapid, sensitive, specific and cost-effective sensing platforms. In summary, AMPs and impedimetric transducers combine excellent properties to produce robust biosensors for the early detection of bacterial infectionsPeer ReviewedPostprint (published version

Nanoparticles for Signaling in Biodiagnosis and Treatment of Infectious Diseases

[EN]Advances in nanoparticle-based systems constitute a promising research area with important implications for the treatment of bacterial infections, especially against multidrug resistant strains and bacterial biofilms. Nanosystems may be useful for the diagnosis and treatment of viral and fungal infections. Commercial diagnostic tests based on nanosystems are currently available. Different methodologies based on nanoparticles (NPs) have been developed to detect specific agents or to distinguish between Gram-positive and Gram-negative microorganisms. Also, biosensors based on nanoparticles have been applied in viral detection to improve available analytical techniques. Several point-of-care (POC) assays have been proposed that can offer results faster, easier and at lower cost than conventional techniques and can even be used in remote regions for viral diagnosis. Nanoparticles functionalized with specific molecules may modulate pharmacokinetic targeting recognition and increase anti-infective efficacy. Quorum sensing is a stimuli-response chemical communication process correlated with population density that bacteria use to regulate biofilm formation

Advances in Rapid Detection and Antimicrobial Susceptibility Tests: A Review

The rise of antibiotic resistance is an emerging problem of the millennium. Clinical microbiology plays an important role in combating the problem by facilitating diagnostics and therapeutics thus managing infection in patients. Diagnostic failures are a major limiting factor during bacterial infection that causes inappropriate use of antibiotics, delay in start up of treatment and decrease in the survival rate during septic conditions. Thus rapid and reliable detection is highly relevant during such bacterial infections and also at the time of disease outbreak as many such pathogens can be used as biothreat agents or bioweapons affecting human health and posing risk to national security. This review highlights the importance of various methods for fast pathogen detection and antimicrobial susceptibility determination. These methods have the potential to provide very precise and rapid ways for bacterial screening and identifying the correct antibiotics to cure infectio

A Rapid and Ultra-sensitive Biosensing Platform based on Tunable Dielectrophoresis for Robust POC Applications

With the ongoing pandemic, there have been increasing concerns recently regarding major public health issues such as abuse of organophosphorus compounds, pathogenic bacterial infections, and biosecurity in agricultural production. Biosensors have long been considered a kernel technology for next-generation diagnostic solutions to improve food safety and public health. Significant amounts of effort have been devoted to inventing novel sensing mechanisms, modifying their designs, improving their performance, and extending their application scopes. However, the reliability and selectivity of most biosensors still have much to be desired, which holds back the development and commercialization of biosensors, especially for on-site and point-of-care (POC) usages. Herein, we introduce an innovative two-phase sensing strategy based on tunable AC electrokinetics and capacitive sensing. By dividing the detection process into a sensitivity-priority step and a selectivity-priority step, the specificity and sensitivity of a biosensor can be significantly improved. A capacitive POC aptasensor is fabricated for the implementation of the 2-phase detection and a quasi-single-cell level detection of limit together with an excellent selectivity is achieved simultaneously. The sensor is capable of handling real-world clinic samples without sophisticated pretreatment. Just after a simple one-step dilution, the developed sensor can detect bacteria no less than 2~3 bacteria/10 µL in raw milk samples within 100 s. Alongside whole bacteria detection, the biosensor can also detect endotoxin, the lipopolysaccharide, in bovine serum samples, with a limit of detection of 10 pg/mL. The biosensor is low-cost and easy to use. This work not only demonstrates a biosensor with significant advantages in sensitivity, selectivity and assay time but also opens up a new horizon for further research of all affinity-based biosensors

New trends in nanoclay-modified sensors

Nanoclays are widespread materials characterized by a layered structure in the nano-scale range. They have multiple applications in diverse scientific and industrial areas, mainly due to their swelling capacity, cation exchange capacity, and plasticity. Due to the cation exchange capacity, nanoclays can serve as host matrices for the stabilization of several molecules and, thus, they can be used as sensors by incorporating electroactive ions, biomolecules as enzymes, or fluorescence probes. In this review, the most recent applications as bioanalyte sensors are addressed, focusing on two main detection systems: electrochemical and optical methods. Particularly, the application of electrochemical sensors with clay-modified electrodes (CLME) for pesticide detection is described. Moreover, recent advances of both electrochemical and optical sensors based on nanoclays for diverse bioanalytes? detection such as glucose, H2O2, organic acids, proteins, or bacteria are also discussed. As it can be seen from this review, nanoclays can become a key factor in sensors? development, creating an emerging technology for the detection of bioanalytes, with application in both environmental and biomedical fields

Development of Nanofiber and Surface Plasmon Resonance Sensors for VOCs, Biochemical, and Bacterial Analysis

It is important to monitor potential exposure to various chemicals and toxicants that may adversely affect both human and environmental health. Biosensors have been developed to identify and quantify these analytes of interest in early warning systems and diagnosis devices. This dissertation implements nanomaterials, such as nanofibers and nanoparticles, into the biological recognition element of a biosensor for selectively and sensitively to detect trace analytes in either gas, liquid, or solid phases.This dissertation is an agglomeration of several different projects that investigates the novel applications of nanomaterials into biosensor designs with two major application focuses: nanofibers and surface plasmon resonance (SPR) The first half of this dissertation focuses on the application of nanofiber surfaces for sensor developments. The nanofibers were fabricated through electrospinning and incorporated into various sensor designs. The first project develops polyaniline nanofibers into a chemiresistor sensor for sensitive detection of VOCs (small chain alcohols) by employing variants of reduced graphene oxides. The second project applies the nanofiber property of high surface area to volume ratio to maximize surface adsorption of EDTA-functionalized silver nanoparticles (AgNPs) as the biorecognition element of this sensor. The EDTA-AgNPs formulates a nickel ion bridge for selective capture and release of NTA and His tagged proteins that can be detected through fluorescent spectroscopy. The second half of this dissertation transitions into the application of surface plasmon resonance for the development of biosensor signal transducers. The third project focused on combining the potential of 3D printing with gold nanoparticles (AuNPs) to create a novel integrated localized SPR (LSPR) sensor surface capable of sensitive protein detection. The synthesis of gold nanoparticles in-situ on a 3D printed prism surface enables the fabrication of a biosensor device for the disposable field of site usage with qualities comparable performances with sensors using commercial optical prisms. The last project focuses on developing an SPR experimental model of a double lipid bilayer membrane. This model mimics the unique structure of the double lipid bilayer membrane system found in the chloroplast, mitochondria, and gram-negative bacteria. This novel experimental model combined with SPR analysis creates a biosensor platform that enables the interrogation of chemical and protein interactions at interfaces such as the gram-negative bacteria cell wall and membrane system

Biodétection de Legionella pneumophila par biocapteur à photocorrosion digitale à base de peptide antimicrobien

La détection de bactéries pathogènes par culture microbienne est lente, nécessite un milieu de culture spécifique pour garantir la croissance de certaines souches bactériennes fastidieuses telle que Legionella pneumophila (L. pneumophila) et en plus pourrait ne pas déceler les bactéries viables mais non cultivables mais restant dangereuse en termes de pathogénicité. Par conséquent, l’usage de biocapteurs pour la détection de L. pneumophila serait, potentiellement, une approche attrayante permettant une détection précise et rapide. Cependant, la sensibilité et la spécificité des biocapteurs dépendent fortement des molécules de bioreconnaissance utilisées. Jusqu'à présent, différents ligands tels que les anticorps, les enzymes, les acides nucléiques fonctionnels (aptamères) et les bactériophages ont été utilisés comme éléments de bioreconnaissance. En raison de leur haute spécificité, Les anticorps de mammifères ont été largement employés pour le développement de divers biocapteurs. Cependant, les anticorps sont connus pour souffrir de la variabilité des lots produits et d'une stabilité limitée, ce qui réduit l'usage et la constance des performances des biocapteurs à base d'anticorps. Au cours des dernières années, les peptides antimicrobiens (PAM) ont été de plus en plus investigués pour des applications thérapeutiques en plus d’être considérés comme des ligands de bioreconnaissance prometteurs en raison de leur grande stabilité et leurs fortes réactivités aux bactéries. Dans le but d’améliorer les performances du biocapteur à DIP, notre hypothèse reposait sur l’usage de bioarchitectures à base de PAM à courte séquence pour une capture efficace des bactéries et une détection considérablement améliorée en raison du transfert de charge plus facilitée vers dans la biopuce à base de semiconducteur III-V. Dans la première phase du projet, nous avons évalué un biocapteur à DIP consistant en une puce d’arséniure de gallium/arséniure de gallium aluminium (GaAs/AlGaAs) fonctionnalisée par le warnericine RK pour la détection directe in situ de L. pneumophila dans l’eau. Nous avons démontré une détection linéaire de L. pneumophila pour des concentrations allant de 103 à 106 CFU/mL. De plus, le nombre relativement important d'interfaces constituant la bioarchitecture d’un tel biocapteur pourrait affecter sa reproductibilité et sa sensibilité. Dans ce cas, la couche de bioreconnaissance est plus mince (~ 2 nm) permettant une distance plus courte entre les bactéries et la surface du biocapteur, ce qui pourrait jouer un rôle important dans la promotion du transfert de charge entre les bactéries et la biopuce, et ainsi nous avons pu démontrer une détection efficace de L. pneumophila à une concentration de 2 x 102 CFU/mL. Cette configuration a permis d’atteindre des LODs de 50 et 100 UFC/mL, respectivement pour de légionnelle dans du PBS et collectées d’échantillons d’eau de tour de refroidissement. Nous avons observé une détection sélective de L. pneumophila sérogroupe 1 (SG1) comparé au sérogroupe 5 (SG 5). Les biocapteurs à photocorrosion digitale (DIP) en configuration sandwich PAM et Ab pourraient être une approche prometteuse pour développer un biocapteur à faible coût, hautement sensible et spécifique pour la détection rapide de L. pneumophila dans l’eau.Abstract: Culture based detection of pathogenic bacteria is time consuming, and needs specific culture medium to identify bacterial strains such as Legionella pneumophila (L. pneumophila) which does not flourish in typical growth medium. Culture based methods cannot detect viable but unculturable bacteria. Therefore, the detection of L. pneumophila with biosensors potentially could be an attractive approach enabling accurate and rapid detection. The sensitivity and specificity of biosensors depend critically on the biorecognition probes employed for the detection. Until now, different elements such as antibodies, enzymes, functional nucleic acids (aptamers) and bacteriophages have been utilized as biorecognition elements. Due to high specificity of antibodies, and the advanced technology of their production, mammalian antibodies have been widely investigated for the development of various biosensors. However, mammalian antibodies are known to suffer from batch-to-batch variation, as well as limited stability, which could reduce the consistent utility of the proposed biosensors. In recent years, antimicrobial peptides (AMPs) have been increasingly investigated for their therapeutic applications. At the same time, AMPs are considered as promising biorecognition ligands due to their high stability and multiple niches for capturing bacteria. The hypothesis was that AMP-based bioarchitectures allows for highly efficient capturing of bacteria, and the short length of the AMP would significantly enhance detection due to limited obstructive charge transfer in the charge sensing biosensor. In the first phase of the project, we investigated a warnericin RK AMP functionalized gallium arsenide/aluminum gallium arsenide (GaAs/AlGaAs) photonic biosensor for direct detection of L. pneumophila in water environments. This approach allowed for detecting a low to high concentration of L. pneumophila (103 to 106 CFU/mL) with a 103 CFU/mL limit of detection (LOD). In addition, a relatively large number of interfaces constituting the architecture of such biosensors could affect their reproducibility and sensitivity. A thinner biorecognition layer (~2 nm) resulted in a shorter distance between bacteria and the biosensor surface, which played important role in promoting charge transfer between bacteria and biochip. L. pneumophila was detected at concentrations as low of 2 x 102 CFU/mL. This configuration allowed the detection sensitivity of L. pneumophila as low as 50 CFU/mL and 100 CFU/mL in clean water and water originated from cooling tower, respectively, along with the selective detection of whole cell L. pneumophila serogroup 1 (SG1) and serogroup 5 (SG5). The proposed AMP and Ab conjugated sandwich architecture with digital photocorrosion (DIP) biosensors is a promising approach for developing low cost, highly sensitive and specific biosensors for rapid detection of L. pneumophila in water environments

Impedimetric Sensors for Bacteria Detection

The application of electrochemical biosensors based on impedance detection has grown during the past years due to their high sensitivity and rapid response, making this technique extremely useful to detect biological interactions with biosensor platforms. This chapter is focused on the use of electrochemical impedance spectroscopy (EIS) for bacterial detection in two ways. On one hand, bacteria presence may be determined by the detection of metabolites produced by bacterial growth involving the media conductivity changes. On the other hand, faster and more selective bacterial detection may be achieved by the immobilization of bacteria on a sensor surface using biorecognition elements (antibodies, antimicrobial peptides, aptamers, etc.) and registering changes produced in the charge transfer resistance (faradic process) or interfacial impedance (nonfaradic process). Here we discuss different types of impedimetric biosensors for microbiological applications, making stress on their most important parameters, such as detection limits, detection times, selectivity, and sensitivity. The aim of the paper was to give a critical review of recent publications in the field and mark the future trends

Nanotechnology‐Based Rapid Diagnostic Tests

Recently, various nanomaterials are used in order to develop nanotechnology‐based rapid diagnostic tests, such as metallic nanoparticles, quantum dots (QDs), silica nanospheres, magnetic nanoparticles, carbon nanotubes (CNTs), silicon nanowires (SiNWs), nanopores, graphene, nanostructured surfaces, and metal films. This novel nanodiagnostic approach will further develop point‐of‐care (POC) diagnostics and monitoring technologies. Nanobiosensors and microarrays of biosensors can create biochip systems and microfluidic platforms that are the most used nanofabrications for rapid diagnostic tests. These nanoplatforms are constructed for the rapid detection of various diseases or pathogen‐specific biomolecules/markers, such as DNA, proteins, whole cells (e.g., circulating tumor cells), and others. The fabrication of small‐scale portable devices with the incorporation of nanostructures will offer many advantages in the early detection of various diseases and health‐threatening infections by pathogens and in the treatment selection and treatment monitoring. The use of nanostructures in in vitro diagnostics gives the opportunity to augment the sensitivity and specificity required in clinical practice, lowers the cost and test time of the assays, and enables portable microfluidic platforms suitable for resource‐constrained settings. In this chapter, all the state‐of‐the‐art advantages in this field are discussed, starting with the nanostructures used for the fabrication of nanobiosensors, nanobiosensors arrays, and nanofluidic platforms and the nanodiagnostic use of rapid tests in the detection of pathogens, in cancer management, and glucose monitoring for the management of diabetes disease

Bacterial detection using an anharmonic acoustic aptasensor

Infectious diseases are currently, one of the greatest global challenges in medicine. Rapid and precise diagnosis and identification of pathogen is important for timely initiation of appropriate antimicrobial therapy. However, many patients with infectious diseases receive empirical treatment rather than appropriate pathogen-directed therapy. As a result antimicrobials have been overused and/or misused, which has ultimately led to antimicrobial resistance (AMR). AMR is broadly considered as the most significant public health threat facing the world today. Policy makers from all over the world have recognised the urgent need for rapid point-of-care (POC) diagnostics that would not only identify pathogens but also provide antimicrobial susceptibility profiles in meaningful timeframe to initiate appropriate antimicrobial therapy and thereby, prevent AMR. Traditional culture-dependent diagnostic methods are still considered as gold standard methods. But they are very slow and generally require 18 to 48 hours with further 8 to 48 hours to perform antibiotic susceptibility test. Among culture-independent methods, PCR and ELISA are label-based, costly, laborious and require specialised equipment and trained personnel to operate them. Lateral flow assays (LFAs) that are low-cost, simple, rapid and paper-based portable detection platforms are very popular, as they can be applied at the POC. [Continues.