Towards portable rapid TB biosensor: Detecting Mycobacterium tuberculosis in raw sputum samples using functionalized screen printed electrodes

A chemiluminescent sensor based on CRISPR-HCR technology for the hypersensitive detection of Mycobacterium tuberculosis

Tuberculosis is a highly infectious bacterial disease caused by Mycobacterium tuberculosis. The spread of this agent has caused serious health problems worldwide, and the rapid and accurate detection of M. tuberculosis is essential for controlling the spread of infection and for preventing the emergence of multidrug-resistant strains. In this study, the trans cleavage ability of CRISPR-Cas12a against single-stranded DNA was combined with hybridization chain reaction and chemiluminescent signal to establish an imaging sensor for the hypersensitive detection of M. tuberculosis DNA. We observed linear relationships between the concentration of M. tuberculosis DNA and the output signal over the ranges of 10 to 200 pM and 200 to 800 pM DNA. The equations of the standard curves were y = 56.08x + 3303, with R2 = 0.9916 for the lower range and y = 15.69x + 10 685, with R2 = 0.9929 for the higher range. The limit of detection was as low as 0.83 pM for genomic DNA, and a plasmid containing an M. tuberculosis-specific sequence was detected at 1 copy per μL. A detection accuracy of 100% was achieved in the analysis of DNA isolated from sputum of hospitalized tuberculosis patients. The sensitivity and specificity of the proposed sensor is combined with a long shelf-life and a low cost of materials. This study introduces a new method for tuberculosis detection and broadens the application of CRISPR-Cas12a-based sensors in clinical diagnosis.

Raman-enhanced sensor based on CRISPR-SERS technology for the rapid and hypersensitive detection of Mycobacterium tuberculosis

Tuberculosis is a highly infectious disease caused by the bacterium Mycobacterium tuberculosis, and the spread of this agent has caused serious health problems worldwide. The rapid and accurate detection of M. tuberculosis is essential for controlling the spread of infection and for preventing the emergence of multidrug-resistant strains. In this study, the powerful trans-cleavage ability of CRISPR-Cas12a for ssDNA was combined with a surface-enhanced Raman spectroscopy (SERS)-based strategy to establish a CRISPR-SERS sensor for the hypersensitive detection of M. tuberculosis DNA. We observed a linear relationship between the concentration of M. tuberculosis DNA and the output signal over the range of 5 to 100 pM. The equation describing the standard curve was y = 24.10x + 1594, with R2 = 0.9914. The limit of detection was as low as 4.42 pM for genomic DNA, and a plasmid containing an M. tuberculosis-specific sequence was detected at 5 copy/μL. A detection accuracy of 100% was achieved in the analysis of DNA isolated from the sputum of hospitalized patients with tuberculosis. The entire detection process is simple to deploy and only takes 50 min and results in the sensitive and specific detection of M. tuberculosis DNA. This study provides a new method for the detection of tuberculosis. The tool is stable and can be utilized on-site, and it thus broadens the diagnostic application of CRISPR-Cas12a-based sensor technology.

Bioreceptor modified electrochemical biosensors for the detection of life threating pathogenic bacteria: a review

The lack of reliable and efficient techniques for early monitoring to stop long-term effects on human health is an increasing problem as the pathogenesis effect of infectious bacteria is growing continuously. Therefore, developing an effective early detection technique coupled with efficient and continuous monitoring of pathogenic bacteria is increasingly becoming a global public health prime target. Electrochemical biosensors are among the strategies that can be utilized for accomplishing that goal with promising potential. In recent years, identifying target biological analytes by interacting with bioreceptors modified electrodes is among the most commonly used detection techniques in electrochemical biosensing strategies. The commonly employed bioreceptors are nucleic acid molecules (DNA or RNA), proteins, antibodies, enzymes, organisms, tissues, and biomimetic components such as molecularly imprinted polymers. Despite the advancement in electrochemical biosensing, developing a reliable and effective biosensor for detecting pathogenic bacteria is still in the infancy stage with so much room for growth. A major milestone in addressing some of the issues and improving the detection pathway is the investigation of specific bacterial detection techniques. The present study covers the fundamental concepts of electrochemical biosensors, human PB illnesses, and the latest electrochemical biosensors based on bioreceptor elements that are designed to detect specific pathogenic bacteria. This study aims to assist researchers with the most up-to-date research work in the field of bio-electrochemical pathogenic bacteria detection and monitoring.

Electrochemical biosensors for clinical detection of bacterial pathogens: advances, applications, and challenges

Bacterial pathogens are responsible for a variety of human diseases, necessitating their prompt detection for effective diagnosis and treatment of infectious diseases. Over recent years, electrochemical methods have gained significant attention owing to their exceptional sensitivity and rapidity. This review outlines the current landscape of electrochemical biosensors employed in clinical diagnostics for the detection of bacterial pathogens. We categorize these biosensors into four types: amperometry, potentiometry, electrochemical impedance spectroscopy, and conductometry, targeting various bacterial components, including toxins, virulence factors, metabolic activity, and events related to bacterial adhesion and invasion. We discuss the merits and challenges associated with electrochemical methods, underscoring their rapid response, high sensitivity, and specificity, while acknowledging the necessity for skilled operators and potential interference from biological and environmental factors. Furthermore, we examine future prospects and potential applications of electrochemical biosensors in clinical diagnostics. While electrochemical biosensors offer a promising avenue for detecting bacterial pathogens, further research in optimizing the robustness and surmounting the challenges hindering their seamless integration into clinical practice is imperative.

Microfluidic QCM enables ultrahigh Q-factor: a new paradigm for in-liquid gravimetric sensing

Acoustic gravimetric biosensors attract attention due to their simplicity, robustness, and low cost. However, a prevailing challenge in these sensors is dissipation which manifests in a low quality factor (Q-factor), which limits their sensitivity and accuracy. To mitigate dissipation of acoustic sensors in liquid environments we introduce an innovative approach in which we combine microfluidic channels with gravimetric sensors. To implement this novel paradigm we chose the quartz crystal microbalance (QCM) as our model system, owing to its wide applicability in biosensing and the relevance of its operating principles to other types of acoustic sensors. We postulate that the crucial determinant for enhancing performance lies in the ratio between the width of the microfluidic channels and the wavelength of the pressure wave generated by the oscillating channel side walls driven by the QCM. Our hypothesis is supported by finite element analysis (FEA) and dimensional studies, which revealed two key factors that affect device performance: (1) the ratio of the channel width to the pressure wavelength ( W / λ p ) and (2) the ratio of the channel height to the shear evanescent wavelength ( H / λ s ). To validate our hypothesis, we fabricated a microfluidic QCM (µ-QCM) and demonstrated a remarkable 10-fold improvement in its dissipation when compared to conventional QCM. The novel microfluidic approach offers several additional advantages, such as direct data interpretation, reduced volume requirement for sample liquids, and simplified temperature control, augmenting the sensor's overall performance. By fostering increased sensitivity, accuracy, and ease of operation, our novel paradigm unlocks new possibilities for advancing gravimetric technologies, potentially for biosensing applications.

Electrochemical flow-through biosensors based on microfiber enzymatic filter discs placed at printed electrodes

A new type of electrochemical biosensors in a flow injection system with printed electrodes were developed and tested. A filter disc (7 mm diameter) with immobilized enzyme was placed at the printed electrode. This conception combines the advantages of biosensors with a bioreceptor at the electrode surface and systems with spatially separated enzymatic and detection parts. Filters of different composition (glass, quartz, and cellulose), thickness, porosity, and ways of binding enzyme to their surface were tested. Only covalent bonds throughout a filter-aminosilane-glutaraldehyde-enzyme chain ensured a long-time and reproducible biosensor response. The developed method of biosensor preparation has been successfully applied to enzymes glucose oxidase, laccase and choline oxidase. The dependences of peak current on detection potential, flow rate, injection volume, analyte concentration as well as biosensor lifetime and reproducibility were investigated for glucose oxidase biosensor. The sensitivity of measurements was two or more times higher than that of biosensor with a mini-reactor filled by powder with immobilized enzyme. The developed biosensor with laccase was tested by determining dopamine in the pharmaceutical infusion product Tensamin®. Results of the analysis (40.0 ± 0.7 mg mL-1, SD = 0.8 mg mL-1, RSD = 1.85 %, N = 11) show a good agreement with the manufacturer's declared value.

Designing a Simple Electrochemical Genosensor for the Detection of Urinary PCA3, a Prostate Cancer Biomarker

This study investigates the feasibility of a simple electrochemical detection of Prostate Cancer Antigen 3 (PCA3) fragments extracted from patients' urine, using a thiolated single-strand DNA probe immobilized on a gold surface without using a redox probe. To enhance the PCA3 recognition process, we conducted a comparative analysis of the hybridization location using two thiolated DNA probes: Probe 1 targets the first 40 bases, while Probe 2 targets the fragment from bases 47 to 86. Hybridization with PCA3 followed, using square wave voltammetry. The limit of detection of the designed genosenors were of the order of (2.2 ng/mL), and (1.6 ng/mL) for Probes 1 and 2, respectively, and the subsequent sensitivities were of the order of (0.09 ± 0.01) µA-1 · µg-1 · mL and (0.10 ± 0.01) µA-1 · µg-1 · mL. Specificity tests were then conducted with the sensor functionalized with Probe 2, as it presents better analytical performances. The electrochemical results indicate that the designed sensor can clearly discriminate a complementary target from a non-complementary one. A further modeling of the calibration curves with the Power Law/Hill model indicates that the dissociation constant increases by one order of magnitude, confirming the ability of the designed sensor to perfectly discriminate complementary targets from non-complementary ones.

Recent advances in electrochemical aptasensors and genosensors for the detection of pathogens

In recent years, pathogenic microorganisms have caused significant mortality rates and antibiotic resistance and triggered exorbitant healthcare costs. These pathogens often have high transmission rates within human populations. Rapid diagnosis is crucial in controlling and reducing the spread of pathogenic infections. The diagnostic methods currently used against individuals infected with these pathogens include relying on outward symptoms, immunological-based and, some biomolecular ones, which mainly have limitations such as diagnostic errors, time-consuming processes, and high-cost platforms. Electrochemical aptasensors and genosensors have emerged as promising diagnostic tools for rapid, accurate, and cost-effective pathogen detection. These bio-electrochemical platforms have been optimized for diagnostic purposes by incorporating advanced materials (mainly nanomaterials), biomolecular technologies, and innovative designs. This review classifies electrochemical aptasensors and genosensors developed between 2021 and 2023 based on their use of different nanomaterials, such as gold-based, carbon-based, and others that employed other innovative assemblies without the use of nanomaterials. Inspecting the diagnostic features of various sensing platforms against pathogenic analytes can identify research gaps and open new avenues for exploration.

An insight to the recent advancements in detection of Mycobacterium tuberculosis using biosensors: A systematic review

Since ancient times, Tuberculosis (TB) has been a severe invasive illness that has been prevalent for thousands of years and is also known as "consumption" or phthisis. TB is the most common chronic lung bacterial illness in the world, killing over 2 million people each year, caused by Mycobacterium tuberculosis (MTB). As per the reports of WHO, in spite of technology advancements, the average rate of decline in global TB infections from 2000-2018 was only 1.6% per year, and the worldwide reduction in TB deaths was only 11%. In addition, COVID-19 pandemic has reversed years of global progress in tackling TB with fewer diagnosed cases. The majority of undiagnosed patients of TB are found in low- and middle-income countries where the GeneXpert MTB/RIF assay and sputum smear microscopy have been approved by the WHO as reference procedures for quickly detecting TB. Biosensors, like other cutting-edge technologies, have piqued researchers' interest since they offer a quick and accurate way to identify MTB. Modern integrated technologies allow for the rapid, low-cost, and highly precise detection of analytes in extremely little amounts of sample by biosensors. Here in this review, we outlined the severity of tuberculosis (TB) and the most recent developments in the biosensors sector, as well as their various kinds and benefits for TB detection. The review also emphasizes how widespread TB is and how it needs accurate diagnosis and effective treatment.

Sensitive and rapid detection of influenza A virus for disease surveillance using dual-probe electrochemical biosensor

Influenza A virus (IAV) can cause influenza, a highly infectious zoonotic respiratory disease, and early detection is essential to prevent and control its rapid spread in the population. Given the limitations of traditional detection methods in clinical laboratories, we report a large surface TPB-DVA COFs (TPB: 1,3,5-Tris(4-aminophenyl) benzene, DVA: 1,4-Benzenedicarboxaldehyd, COFs: Covalent organic frameworks) nanomaterial modified electrochemical DNA biosensor, which has dual-probe specific recognition and signal amplification. The biosensor enables quantitative detection of influenza A viruses' complementary DNA (cDNA) from 10 fM to 1 × 10³ nM (LOD = 5.42 fM) with good specificity and high selectivity. The reliability of the biosensor and portable device was verified by comparing the virus concentrations in animal tissues with those measured by digital droplet PCR (ddPCR) (P > 0.05). Moreover, the potential for influenza surveillance in this work was demonstrated by detecting the tissue samples from mice at different stages of infection. In summary, the good performance of this electrochemical DNA biosensor we proposed suggested it has the potential to be a rapid detection device for the influenza A virus, which could assist doctors or other professionals in obtaining rapid and accurate results for outbreak investigation and disease diagnosis.

Point-of-care test for tuberculosis: a boon in diagnosis

Rapid diagnosis of tuberculosis (TB) is an effective measure to eradicate this infectious disease worldwide. Traditional methods for screening TB patients do not provide an immediate diagnosis and thus delay treatment. There is an urgent need for the early detection of TB through point-of-care tests (POCTs). Several POCTs are widely available at primary healthcare facilities that assist in TB screening. In addition to the currently used POCTs, advancements in technology have led to the discovery of newer methods that provide accurate and fast information independent of access to laboratory facilities. In the present article, the authors tried to include and describe the potential POCTs for screening TB in patients. Several molecular diagnostic tests, such as nucleic acid amplification tests, including GeneXpert and TB-loop-mediated isothermal amplification, are currently being used as POCTs. Besides these methods, the pathogenic component of Mycobacterium tuberculosis can also be utilized as a biomarker for screening purposes through immunological assays. Similarly, the host immune response to infection has also been utilized as a marker for the diagnosis of TB. These novel biomarkers might include Mtb85, interferon-γ inducible protein-10, volatile organic compounds, acute-phase proteins, etc. Radiological tests have also been observed as POCTs in the TB screening POCT panel. Various POCTs are performed on samples other than sputum, which further eases the screening process. These POCTs should not require large-scale manpower and infrastructure. Hence, POCT should be able to identify patients with M. tuberculosis infection at the primary healthcare level only. There are several other advanced techniques that have been proposed as future POCTs and have been discussed in the present article.