Rapid Colorimetric Quantita2tive Portable Platform for Detection of Brucella melitensis Based on a Fluorescence Resonance Energy Transfer Assay and Nanomagnetic Particles.

Brucellosis is a bacterial zoonotic disease that requires major attention for both health and financial facilities in many parts of the world including the Mediterranean and the Middle East. The existing gold standard diagnosis relies on the culturing technique, which is costly and time-consuming with a duration of up to 45 days. The Brucella protease biosensor represents a new detection approach that will lead to low-cost point-of-care devices for sensitive Brucella detection. In addition, the described diagnostic device is portable and simple to operate by a nurse or non-skilled clinician making it appropriate for the low-resource setting. In this study, we rely on the total extracellular protease proteolytic activity on specific peptide sequences identified using the FRET assay by high-throughput screening from the library of peptide (96 short peptides such as dipeptides and tripeptides) substrates for Brucella melitensis (B. melitensis). The B. melitensis-specific protease substrate was utilized in the development of the paper-based colorimetric assay. Two specific and highly active dipeptide substrates were identified (FITC-Ahx-K-r-K-Ahx-DABCYL and FITC-Ahx-R-r-K-Ahx-DABCYL). The peptide-magnetic bead nanoprobe sensors developed based on these substrates were able to detect the Brucella with LOD as low as 1.5 × 102 and 1.5 × 103 CFU/mL using K-r dipeptide and R-r dipeptide substrates, respectively, as the recognition element. The samples were tested using this sensor in few minutes. Cross-reactivity studies confirmed that the other proteases extracted from closely related pathogens have no significant effect on the sensor. To the best of our knowledge, this assay is the first assay that can be used with low-cost, rapid, direct, and visual detection of B. melitensis.

A cross-sectional study on adult lifestyle habits during the COVID-19 pandemic.

COVID-19 has spread and developed into a pandemic disease, forcing countries to impose challenging protocols and lockdowns. This study assessed shopping, food consumption behavior, and feelings in Jordan and several Arab countries during the COVID-19 pandemic. A cross-sectional web-based survey among the Middle East population was conducted using an online questionnaire between July and September 2022. Participants were requested to answer a standardized and validated structured questionnaire. Demographic information, shopping behavior information, and mental health data were requested. A total of 542 respondents were included in the study. During COVID-19 quarantine, participants (68.6%) reported decreased shopping frequency and buying more food than usual (37.5%). Cereals and legumes were the primary food types stored by participants (76.9%). Multiple logistic regression revealed the age of the participant as a significant factor affecting storing of food (being ≤ 25 years old (OR = 0.456, p value = 0.038)). 75.7% of female participants eat less frequently in restaurants than usual. In contrast, among males, 48.5% reported that they eat at restaurants less frequently than usual. The country of residency and gender were the significant factors affecting negative feelings and emotions. Participants in countries other than Jordan had a higher negative feeling score (Beta = 0.086, p value = 0.042). Furthermore, females had a higher negative feeling score (Beta = -0.128, p value = 0.003) as the negative feelings score for females was 3.58 (SD = 5.443). On the other hand, it was 2.10 (SD = 5.091) for males. The COVID-19 pandemic has altered Jordanians' attitudes, shopping, and food consumption habits. Although positive behaviors have improved, such as shopping less frequently, eating home-cooked meals, and dining with family, frequent snacking and food storage have increased. Finally, public awareness of shopping and food consumption habits should be promoted.

Glucosamine substituted sulfonylureas: IRS-PI3K-PKC-AKT-GLUT4 insulin signalling pathway intriguing agent.

Normally, skeletal muscle accounts for 70-80% of insulin-stimulated glucose uptake in the postprandial hyperglycemia state. Consequently, abnormalities in glucose uptake by skeletal muscle or insulin resistance (IR) are deemed as initial metabolic defects in the pathogenesis of type 2 diabetes mellitus (T2DM). Globally, T2DM is growing in exponential proportion. The majority of T2DM patients are treated with sulfonylureas in combination with other drugs to improve insulin sensitivity. Glycosylated sulfonylureas (sulfonylurea-glucosamine analogues) are modified analogues of sulfonylurea that have been previously reported to possess antidiabetic activity. The aim of this study was to evaluate the impact of glycosylated sulfonylureas on the insulin signalling pathway at the molecular level using L6 skeletal muscle cell (in vitro) and extracted soleus muscle (ex vivo) models. To create an in vitro model, insulin resistance was established utilizing a high insulin-glucose approach in differentiated L6 muscle cells from Rattus norvegicus. Additionally, for the ex vivo model, extracted soleus muscles, adult Sprague-Dawley rats were subjected to a solution containing 25 mmol L-1 glucose and 100 mmol L-1 insulin for 24 hours to induce insulin resistance. After insulin resistance, compounds under investigation and standard medicines (metformin and glimepiride) were tested. The differential expression of PI3K, IRS-1, PKC, AKT2, and GLUT4 genes involved in the insulin signaling pathway was evaluated using qPCR. The evaluated glycosylated sulfonylurea analogues exhibited a significant increase in the gene expression of insulin-dependent pathways both in vitro and ex vivo, confirming the rejuvenation of the impaired insulin signaling pathway genes. Altogether, glycosylated sulfonylurea analogues described in this study represent potential therapeutic anti-diabetic drugs.

Development of Rapid Aptamer-Based Screening Assay for the Detection of Covid-19 Variants.

The development of a colorimetric severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection assay with the WHO published ASSURED criteria is reported, in which the biosensor should have the following characteristics of (i) being affordable for low-income communities, (ii) sensitive, (iii) specific, (iv) user-friendly to be used by non-skilled personnel, (v) rapid and robust, (vi) equipment-free, and (vii) delivered to the end-users as a simple and easy to use point-of-care tool. Early viral infection detection prevents virus spread and controls the epidemic. We herein report the development of a colorimetric assay in which SARS-COV-2 variants can be detected by colorimetric observation of color on the sensing cotton swab surface. Using the developed biosensor assay, it is possible to discriminate between the various SARS-CoV-2 variants with a LOD of 100 ng/mL within 4 min including sample preconcentration and incubation step. The results illustrated the development of a SARS-CoV-2 colorimetric biosensor that can be mass produced, with low-reagent cost, and can be read-out visually in the field by nonskilled personnel.

Antibiotic-Lysobacter enzymogenes proteases combination as a novel virulence attenuating therapy.

Minimizing antibiotic resistance is a key motivation strategy in designing and developing new and combination therapy. In this study, a combination of the antibiotics (cefixime, levofloxacin and gentamicin) with Lysobacter enzymogenes (L. enzymogenes) bioactive proteases present in the cell- free supernatant (CFS) have been investigated against the Gram-positive methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA) and the Gram-negative Escherichia coli (E. coli O157:H7). Results indicated that L. enzymogenes CFS had maximum proteolytic activity after 11 days of incubation and higher growth inhibitory properties against MSSA and MRSA compared to E. coli (O157:H7). The combination of L. enzymogenes CFS with cefixime, gentamicin and levofloxacin at sub-MIC levels, has potentiated their bacterial inhibition capacity. Interestingly, combining cefixime with L. enzymogenes CFS restored its antibacterial activity against MRSA. The MTT assay revealed that L. enzymogenes CFS has no significant reduction in human normal skin fibroblast (CCD-1064SK) cell viability. In conclusion, L. enzymogenes bioactive proteases are natural potentiators for antimicrobials with different bacterial targets including cefixime, gentamicin and levofloxacin representing the beginning of a modern and efficient era in the battle against multidrug-resistant pathogens.

Knowledge, practice and attitude associated with SARS-CoV-2 Delta Variant among adults in Jordan.

COVID-19 infection is a global pandemic health emergency. This contagious disease was caused by the Severe Acute Respiratory Syndrome Coronavirus­2 (SARS­CoV-2) which is mutating over time. In 2021, the Delta variant became the most dominant transmissible form. During the crisis, human practice and knowledge were critical in the overall efforts to encompass the outbreak. A cross-sectional, web-based approach was conducted among adults in Jordan to quantify knowledge, attitude, and practices towards SARS-CoV-2 (Delta variant). This research was carried out between 15th April and 15th of May 2021. The study questionnaire consisted of four sections including the participant's demographics, knowledge, practices and attitude. Comparative evaluation of responses was accomplished using a scoring system. Respondents who scored above the mean score (60%) on the item measured were categorized as knowledgeable, having a positive attitude, and good practices. Participants were allocated to one of the three groups; medical, non-medical and others (unemployed and housewives). Data collected was analyzed using Statistical Package for Social Sciences (SPSS) version 23.0 software. A variance test to assess the statistical difference between groups was used. Pearson's chi-squared test was applied to compare the variables and identify significant predictors. Of the participants, 308 (66%) were in the age group of 18-25yrs, 392 (84.1%) females, 120 (25.8%) employed and 346 (74.2%) unemployed. The principle source of knowledge was social media (291, 62.4%). Interestingly, participants had adequate overall knowledge. The mean knowledge score was 22.6 (± 0.19), 20.6 (± 0.19), and 21.3 (± 0.18) for the medical, the non-medical and the others group, respectively. Also, participants showed a positive attitude and good practices towards SARS-CoV-2 (Delta variant). The mean practice score for medical, the non-medical and the others groups was 7.35 (± 0.25), 7.38 (± 0.24), 7.35 (± 0.24) and the mean attitude score was 10.8 (± 0.16), 9.4 (± 0.21), 9.5 (± 0.22), respectively. The studied groups generally had good knowledge, positive attitudes and good practices about SARS-CoV-2 (Delta variant). This was expected due to the authorities' successful management of the pandemic and the high educational level of the Jordanian society, bearing in mind the economic and social impact of COVID-19 disease.

An Electrochemical Sensor for the Detection of Albendazole Using Glassy Carbon Electrode Modified with Platinum-Palladium Nanocomposites.

An electroanalytical electrode for the detection of albendazole (ABZ) active ingredient in pharmaceutical dosage form and in contaminated animal-derived products was developed using a glassy carbon electrode modified with platinum-palladium nanoparticles. The electro-catalytic performance of the bimetallic-modified glassy carbon electrode was compared with its bare counterpart. Under optimized conditions, the modified electrode revealed two well-resolved anodic peak currents at 1.10 and 1.23 V using differential pulse voltammetry. Pure ABZ, as well as ABZ in spiked foods (milk and chicken), were detected with little interference from the food matrix. This electrode demonstrated high sensitivity and applicability, with a lower limit of detection of 0.08 µmol L-1 in aqueous solution and 10 µmol L-1 in the contaminated ground chicken and 100 µmol L-1 in the contaminated milk sample. The fabricated sensor is low in cost and appropriate for the estimation of albendazole in tablet dosage forms and biological samples, and so can act as a quality control tool in the pharmaceutical and food industry.

In Vitro and In Vivo Antidiabetic Activity, Phenolic Content and Microscopical Characterization of Terfezia claveryi.

Terfezia claveryi (T. claveryi) is used by traditional healers in the Middle East region to treat several diseases, including diabetes. The present study evaluated the total phenolic and investigated the blood-glucose-lowering potential of different aqueous extracts of this selected truffle using in vitro and in vivo models. The phytochemical profile was examined using UPLC-MS. The macerate and the microwave-assisted extract were the richest in phenolic compounds. All T. claveryi extracts exhibited a remarkable α-glucosidase inhibitory effect in vitro, with an IC50 of 2.43, 3.26, 5.18 and 3.31 mg/mL for the aqueous microwave-assisted extract macerate, infusion and decoction, respectively. On the other hand, in the high-fat diet alloxan-induced diabetic mice model, all tested crude aqueous extracts exhibited a significant antihyperglycemic activity (p < 0.05). Four hours after the administration of the 250 mg/kg dose, the macerate was able to induce a 29.4% blood-glucose-lowering effect compared to a 24.8% reduction induced by the infusion, which was sustained for a further two hours. The hypoglycemic effect (29.3% and 32.4%) was also recorded six hours after the administration of the single dose 500 mg/kg of the macerate and the infusion, respectively. Truffle extracts exhibited antidiabetic activity both in vitro and in vivo, providing a rationale for the traditional use as a natural hypoglycemic.

Development of a Rapid Immuno-Based Screening Assay for the Detection of Adenovirus in Eye Infections.

Despite progress in fighting infectious diseases, human pathogenesis and death caused by infectious diseases remain relatively high worldwide exceeding that of cancer and cardiovascular diseases. Human adenovirus (HAdV) infects cells of the upper respiratory tract causing flu-like symptoms that are accompanied by pain and inflammation. Diagnosis of HAdV is commonly achieved by conventional methods such as viral cultures, immunoassays, and polymerase chain reaction (PCR) techniques. However, there are a variety of problems with conventional methods including slow isolation and propagation, inhibition by neutralizing antibodies, low sensitivity of immunoassays, and the diversity of HAdV strains for the PCR technique. Herein, we report the development and evaluation of a novel, simple, and reliable nanobased immunosensing technique for the rapid detection of human adenoviruses (HAdVs) that cause eye infections. This rapid and low-cost assay can be used for screening and quantitative tests with a detection limit of 102 pfu/mL in less than 2 min. The sensing platform is based on a sandwich assay that can detect HAdVs visually by a color change. Sensor specificity was demonstrated using other common viral antigens, including Flu A, Flu B, coronavirus (COV), and Middle East respiratory syndrome coronavirus (MERS COV). This cotton-based testing device potentially exhibits many of the desired characteristics of a suitable point-of-care and portable test, which can be carried out by nurses or clinicians especially for low-resource settings.

A Portable Nanoprobe for Rapid and Sensitive Detection of SARS-CoV-2 S1 Protein.

Simple, timely, and precise detection of SARS-CoV-2 in clinical samples and contaminated surfaces aids in lowering attendant morbidity/mortality related to this infectious virus. Currently applied diagnostic techniques depend on a timely laboratory report following PCR testing. However, the application of these tests is associated with inherent shortcomings due to the need for trained personnel, long-time centralized laboratories, and expensive instruments. Therefore, there is an interest in developing biosensing diagnostic frontiers that can help in eliminating these shortcomings with a relatively economical, easy-to-use, well-timed, precise and sensitive technology. This study reports the development of fabricated Q-tips designed to qualitatively and semi-quantitatively detect SARS-CoV-2 in clinical samples and contaminated non-absorbable surfaces. This colorimetric sensor is engineered to sandwich SARS-CoV-2 spike protein between the lactoferrin general capturing agent and the complementary ACE2-labeled receptor. The ACE2 receptor is decorated with an orange-colored polymeric nanoparticle to generate an optical visual signal upon pairing with the SARS-CoV-2 spike protein. This colorimetric change of the Q-tip testing zone from white to orange confirms a positive result. The visual detection limit of the COVID-19 engineered colorimetric Q-tip sensor was 100 pfu/mL within a relatively short turnaround time of 5 min. The linear working range of quantitation was 103-108 pfu/mL. The engineered sensor selectively targeted SARS-CoV-2 spike protein and did not bind to another coronavirus such as MERS-CoV, Flu A, or Flu B present on the contaminated surface. This novel detection tool is relatively cheap to produce and suitable for onsite detection of COVID-19 infection.

Fluoroquinolones' Biological Activities against Laboratory Microbes and Cancer Cell Lines.

Development of novel derivatives to rein in and fight bacteria have never been more demanding, as microbial resistance strains are alarmingly increasing. A multitude of new fluoroquinolones derivatives with an improved spectrum of activity and/or enhanced pharmacokinetics parameters have been widely explored. Reporting novel antimicrobial agents entails comparing their potential activity to their parent drugs; hence, parent fluoroquinolones have been used in research as positive controls. Given that these fluoroquinolones possess variable activities according to their generation, it is necessary to include parent compounds and market available antibiotics of the same class when investigating antimicrobial activity. Herein, we provide a detailed guide on the in vitro biological activity of fluoroquinolones based on experimental results published in the last years. This work permits researchers to compare and analyze potential fluoroquinolones as positive control agents and to evaluate changes occurring in their activities. More importantly, the selection of fluoroquinolones as positive controls by medicinal chemists when investigating novel FQs analogs must be correlated to the laboratory pathogen inquest for reliable results.

RNA Coronaviruses' Outbreaks: Recent Progress on the SARS-CoV-2 Pandemic Diagnostic Tests, Vaccination and Therapeutics.

Coronaviruses are RNA-infective viruses that could be considered principal players in universal high-profile outbreaks, namely the Severe Acute Respiratory Syndrome (SARS, 2002-2003), the Middle East Respiratory Syndrome (MERS, 2012) and the continuing novel coronavirus disease (COVID-19, 2019) pandemic. RNA coronaviruses infections raise public health concerns with infections' severity ranging from serious pandemics and highly contagious infections to common influenza episodes. With a wide consensus concerning the seminal role of early detection of the infectious agent on the clinical prognosis, recent technological endeavors have facilitated the rapid, sensitive and specific diagnosis of viral infections. Given that the burst of confirmed cases of the novel coronavirus disease 2019 (COVID-19) are climbing steeply, and we are amid this pandemic, this work will center at the respiratory RNA-viruses outbreaks, including the three coronaviruses-related pandemics, emphasizing on the approved diagnostic approaches, outlining therapeutic clinical trials as well as vaccine candidates. Based on the accumulated data and knowledge on the previous RNA-virus outbreaks, this review aspires to link the current intervention measures against SARS-CoV-2 infection with the previous interventions and to provide a roadmap for any possible future measures.

Plants Secondary Metabolites as Blood Glucose-Lowering Molecules.

Recently, significant advances in modern medicine and therapeutic agents have been achieved. However, the search for effective antidiabetic drugs is continuous and challenging. Over the past decades, there has been an increasing body of literature related to the effects of secondary metabolites from botanical sources on diabetes. Plants-derived metabolites including alkaloids, phenols, anthocyanins, flavonoids, stilbenoids, saponins, tannins, polysaccharides, coumarins, and terpenes can target cellular and molecular mechanisms involved in carbohydrate metabolism. In addition, they can grant protection to pancreatic beta cells from damage, repairing abnormal insulin signaling, minimizing oxidative stress and inflammation, activating AMP-activated protein kinase (AMPK), and inhibiting carbohydrate digestion and absorption. Studies have highlighted many bioactive naturally occurring plants' secondary metabolites as candidates against diabetes. This review summarizes the current knowledge compiled from the latest studies published during the past decade on the mechanism-based action of plants-derived secondary metabolites that can target various metabolic pathways in humans against diabetes. It is worth mentioning that the compiled data in this review will provide a guide for researchers in the field, to develop candidates into environment-friendly effective, yet safe antidiabetics.

Simple and rapid peptide nanoprobe biosensor for the detection of Legionellaceae.

This study demonstrates the development of a sensitive, specific, and quantitative peptide-based nanoprobe prototype assay for the detection of Legionellaceae in a simple way and in a short time. In this work, proteases present in the culture supernatants of Legionella spp. were used as a biomarker. Fluorogenic peptide substrates, specific to Legionella strains culture supernatant proteases, were identified. Peptidases produced a significant increase in the fluorescence intensity following the cleavage of the dipeptide fluorogenic substrates. The specific substrates were identified and coupled with carboxyl-terminated nano-magnetic particles (NMPs). On the other hand, the C-terminal was conjugated with the cysteine residue to covalently integrate with a gold sensing platform via the Au-S linkage. Four different sensors were fabricated from the four specific substrates, which were treated with the protesase of six different species of Legionella. In the presence of specific protease, the peptide sequence is digested and the magnetic nanobeads moved out of the gold surface, resulting in the apparence of gold color. One of the nanoprobes sensitivity detects as low as 60 CFU mL-1 of Legionella anisa, Legionella micdadei, and Fluoribacter dumoffii. The cross-reactivity of the sensors was tested using other closely associated bacterial species and no significant cross-reactivity of the sensors was found. It is envisaged that this assay could be useful for screening purposes or might be supportive for the fast and easy detection of Legionella protease activity for water monitoring purposes.

Design, synthesis and antimicrobial evaluation of novel glycosylated-fluoroquinolones derivatives.

Herein we report the design, synthesis and biological evaluation of structurally modified ciprofloxacin, norfloxacin and moxifloxacin standard drugs, featuring amide functional groups at C-3 of the fluoroquinolone scaffold. In vitro antimicrobial testing against various Gram-positive bacteria, Gram-negative bacteria and fungi revealed potential antibacterial and antifungal activity. Hybrid compounds 9 (MIC 0.2668 ± 0.0001 mM), 10 (MIC 0.1358 ± 00025 mM) and 13 (MIC 0.0898 ± 0.0014 mM) had potential antimicrobial activity against a fluoroquinolone-resistant Escherichia coli clinical isolate, compared to ciprofloxacin (MIC 0.5098 ± 0.0024 mM) and norfloxacin (MIC 0.2937 ± 0.0021 mM) standard drugs. Interestingly, compound 10 also exerted potential antifungal activity against Candida albicans (MIC 0.0056 ± 0.0014 mM) and Penicillium chrysogenum (MIC 0.0453 ± 0.0156 mM). Novel derivatives and standard fluoroquinolone drugs exhibited near-identical cytotoxicity levels against L6 muscle cell-line, when measured using the MTT assay.

Fluoroquinolones structural and medicinal developments (2013-2018): Where are we now?

Fluoroquinolones are considered one of the widely utilized antibiotics, specifically, with the recent development of newer generations such as moxifloxacin, delafloxacin and finafloxacin which possess a wider spectrum of activity and improved bioavailability. However, alarming increase in bacterial resistance reports worldwide incites medicinal chemists to employ guided-biologically-oriented-synthesis-strategies toward the modulation of quinolones derivatives activity. At present, quinolone scaffold diverse biological activities prompted the fortuitous discovery of novel antimicrobial and anticancer derivatives. Herein, the opponent arguments (2013-2015) regarding the structure activity relationships of fluoroquinolones' antibacterial, anticancer, antifungal activities are inscribed.

Portable paper-based colorimetric nanoprobe for the detection of Stachybotrys chartarum using peptide labeled magnetic nanoparticles.

A colorimetric assay is presented for the detection of Stachybotrys chartarum proteases as biomarkers. The assay comprises a gold film acting as solid support and carrying an immobilized peptide substrate that is specific for S. chartarum protease. The substrate was conjugated to black magnetic nanoparticles (MNPs) to form a monolayer on the gold film. Hence, detection nanoprobe is black. If, however, the peptide-MNP fragments are cleaved by S. chartarum proteases present in a sample, the golden color of the detecting nanoprobe becomes apparent so that positive visual readout is enabled. The method was applied to the determination of S. chartarum in (spiked) environmental samples. The limit of detection ranges from 10 to 100 spores·mL-1 depending on the kind of sample (culture, dust, mold and soil). Assay specificity was examined for Aspergillus flavus, Fusarium solani. Penicillin chrysogenum, and Saccharomyces cerevisiae, and negative readouts were observed visually for all samples, except for those also containing S. chartarum. Graphical abstract Schematic presentation of S. chartarum colorimetric nanoprobe.

Engineered colorimetric detection of Staphylococcus aureus extracellular proteases.

This work describes the engineering of a feasible, sensitive, and specific colorimetric assay for the detection of Staphylococcus aureus (S. aureus) extracellular protease production, using a tailored agar-based readout platform. Firstly, S. aureus protease production was evaluated using different culture media. Maximum proteolytic activity was achieved after 24 h of incubation in brain heart infusion (BHI) broth at 37 °C, as confirmed using azo-casein and Sigma's non-specific protease activity assays. Secondly, to enhance proteolysis detection, novel agar-based platform readouts for S. aureus proteases were developed. Clear proteolytic zones were observed after 48 h of incubation at 37 °C, using an agar-agar platform supplemented with 3% skim milk as a non-specific protease substrate. Thirdly, the colorimetric visualization of S. aureus proteolytic zones was evaluated using three different techniques, namely, the use of chromogenic media, dye flooding over the platform, and protease staining prior to testing. Colorimetric sensing of proteolysis was achieved by applying a Bromocresol Purple-colored protease solution on a skim milk plate count agar-PEG 4000 readout platform. Color change (yellow to burgundy) indicated a positive readout after 15 min of incubation. The lowest limit of S. aureus detection was 102 CFU mL-1. Moreover, direct detection of S. aureus BHI culture was achieved by sensing the pH change because of protease production, using bromothymol blue dye. A light-green color represented a positive readout. A direct relationship between S. aureus culture concentration and color change was observed, with a detection limit as low as 103 CFU mL-1. Examination of blind samples of Escherichia coli and S. aureus showed the potential of this assay to specifically detect S. aureus in situ. Therefore, the developed approach is anticipated to help detect S. aureus for biomedical applications.

Rapid Colorimetric Detection of Pseudomonas aeruginosa in Clinical Isolates Using a Magnetic Nanoparticle Biosensor.

A rapid, sensitive, and specific colorimetric biosensor based on the use of magnetic nanoparticles (MNPs) was designed for the detection of Pseudomonas aeruginosa in clinical samples. The biosensing platform was based on the measurement of P. aeruginosa proteolytic activity using a specific protease substrate. At the N-terminus, this substrate was covalently bound to MNPs and was linked to a gold sensor surface via cystine at the C-terminus of the substrates. The golden sensor appears black to naked eyes because of the coverage of the MNPs. However, upon proteolysis, the cleaved peptide-MNP moieties will be attracted by an external magnet, revealing the golden color of the sensor surface, which can be observed by the naked eye. In vitro, the biosensor was able to detect specifically and quantitatively the presence of P. aeruginosa with a detection limit of 102 cfu/mL in less than 1 min. The colorimetric biosensor was used to test its ability to detect in situ P. aeruginosa in clinical isolates from patients. This biochip is anticipated to be useful as a rapid point-of-care device for the diagnosis of P. aeruginosa-related infections.