Zepto-molar electrochemical detection of Brucella genome based on gold nanoribbons covered by gold nanoblooms

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.

Synchronized Chemotherapy/Photothermal Therapy/Sonodynamic Therapy of Human Triple-Negative and Estrogen Receptor-Positive Breast Cancer Cells Using a Doxorubicin-Gold Nanoclusters-Albumin Nanobioconjugate

OBJECTIVE

Novel strategies for treating triple-negative breast cancer (TNBC) are ongoing because of the lack of standard-of-care treatment. Nanoframed materials with a protein pillar are considered a valuable tool for designing multigoals of energy-absorbing/medication cargo and are a bridge to cross-conventional treatment strategies.

METHODS

Nanobioconjugates of gold nanoclusters-bovine serum albumin (AuNCs-BSA) and doxorubicin-AuNCs-BSA (Dox-AuNCs-BSA) were prepared and employed as a simultaneous double photosensitizer/sonosensitizer and triple chemotherapeutic/photosensitizer/sonosensitizer, respectively.

RESULTS

The highly stable AuNCs-BSA and Dox-AuNCs-BSA have ζ potentials of -29 and -18 mV, respectively, and represent valuable photothermal and sonodynamic activities for the combination of photothermal therapy and sonodynamic therapy (PTT/SDT) and synchronized chemotherapy/photothermal therapy/sonodynamic therapy (CTX/PTT/SDT) of human TNBC cells, respectively. The efficiency of photothermal conversion of AuNCs-BSA was calculated to be a promising value of 32.9%. AuNCs-BSA and Dox-AuNCs-BSA were activated on either laser light irradiation or ultrasound exposure with the highest efficiency on the combination of both types of radiation. CTX/PTT/SDT of MCF-7 and MDA-MB-231 breast cancer cell lines by Dox-AuNCs-BSA were evaluated with the MTT cell proliferation assay and found to progress synergistically.

CONCLUSION

Results of the MTT assay, detection of the generation of intracellular reactive oxygen species and occurrence of apoptosis in the cells confirmed that CTX/PTT/SDT by Dox-AuNCs-BSA was attained with lower needed doses of the drug and improved tumor cell ablation, which would result in the enhancement of therapeutic efficacy and overcoming of therapeutic resistance.

Integration of DNA barcoding and nanotechnology in drug delivery

In recent years' development in nanotechnology utilization of DNA barcodes with potential benefit of nanoparticulate system is a hallmark for novel advancement in healthcare, biomedical and research sector. Interplay of biological barcoding with nanodimensional system encompasses innovative technologies to offer unique advantages of ultra-sensitivity, error-free, accuracy with minimal label reagents, and less time consumption in comparison to conventional techniques like ELISA, PCR, culture media, electrophoresis. DNA barcoding systems used as universal novel tool for identification and multiplex structural detection of proteins, DNAs, toxins, allergens, and nucleic acids of humans, viruses, animals, bacteria, plants as well as personalized treatment in ovarian cancer, AIDS-related Kaposi sarcoma, breast cancer and cardiovascular diseases. Barcoding tools offer substantial attention in drug delivery, in-vivo screening, gene transport for theranostics, bioimaging, and nano-biosensors applications. This review article outlines the recent advances in nano-mediated DNA barcodes to explore various applications in detection of cancer markers, tumor cells, pathogens, allergens, as theranostics, biological sensors, and plant authentication. Furthermore, it summarizes the diverse newer technologies such as bio-barcode amplification (BBA), Profiling Relative Inhibition Simultaneously in Mixtures (PRISM) and CRISPR-Cas9 gene knockout and their applications as sensors for detections of antigens, allergens, and other specimens.

Recent advances in electrochemical strategies for bacteria detection

Introduction: Bacterial infections have always been a major threat to public health and humans' life, and fast detection of bacteria in various samples is significant to provide early and effective treatments. Cell-culture protocols, as well-established methods, involve labor-intensive and complicated preparation steps. For overcoming this drawback, electrochemical methods may provide promising alternative tools for fast and reliable detection of bacterial infections. Methods: Therefore, this review study was done to present an overview of different electrochemical strategy based on recognition elements for detection of bacteria in the studies published during 2015-2020. For this purpose, many references in the field were reviewed, and the review covered several issues, including (a) enzymes, (b) receptors, (c) antimicrobial peptides, (d) lectins, (e) redox-active metabolites, (f) aptamer, (g) bacteriophage, (h) antibody, and (i) molecularly imprinted polymers. Results: Different analytical methods have developed are used to bacteria detection. However, most of these methods are highly time, and cost consuming, requiring trained personnel to perform the analysis. Among of these methods, electrochemical based methods are well accepted powerful tools for the detection of various analytes due to the inherent properties. Electrochemical sensors with different recognition elements can be used to design diagnostic system for bacterial infections. Recent studies have shown that electrochemical assay can provide promising reliable method for detection of bacteria. Conclusion: In general, the field of bacterial detection by electrochemical sensors is continuously growing. It is believed that this field will focus on portable devices for detection of bacteria based on electrochemical methods. Development of these devices requires close collaboration of various disciplines, such as biology, electrochemistry, and biomaterial engineering.

Delineating the Role of Tailored Gold Nanostructures at the Biointerface

Gold (Au) has emerged as a superior element, because of its widespread applications in electronic and medical fields. The desirable physical, chemical, optical, and inherent enzyme-like properties of Au are efficiently exploited for detection, diagnostic, and therapeutic purposes. Au offers a unique advantage of fabricating gold nanostructures (GNS) having exact physical, chemical, optical, and enzyme-like properties required for the specific biomedical application. In this Review, the emerging trend of GNS for various biomedical applications is highlighted. Some notable structural and chemical modifications achieved for the detection of biomolecules, pathogens, diagnosis of diseases, and therapeutic applications are discussed in brief. The limitations of GNS during biomedical usage are highlighted and the way forward to overcome these limitations are discussed.

Integrating programmable DNAzymes with electrical readout for rapid and culture-free bacterial detection using a handheld platform

The detection and identification of bacteria currently rely on enrichment steps such as bacterial culture and nucleic acid amplification to increase the concentration of target analytes. These steps increase assay time, cost and complexity, making it difficult to realize a truly rapid point-of-care test. Here we report the development of an electrical assay that uses electroactive RNA-cleaving DNAzymes (e-RCDs) to identify specific bacterial targets and subsequently release a DNA barcode for transducing a signal onto an electrical chip. Integrating e-RCDs into a two-channel electrical chip with nanostructured electrodes provides the analytical sensitivity and specificity needed for clinical analysis. The e-RCD assay is capable of detecting 10 CFU (equivalent to 1,000 CFU ml^-1) of Escherichia coli selectively from a panel containing multiple non-specific bacterial species. Clinical evaluation of this assay using 41 patient urine samples demonstrated a diagnostic sensitivity of 100% and specificity of 78% at an analysis time of less than one hour compared with the several hours needed for currently used culture-based methods.

Phototherapy and Sonotherapy of Melanoma Cancer Cells Using Nanoparticles of Selenium-Polyethylene Glycol-Curcumin as a Dual-Mode Sensitizer

Background:

As an alternative form of cancer therapy, photothermal therapy (PTT) and sonodynamic therapy (SDT) using nanomaterials are in development. Nanomaterials can act as energy absorber as well as anti-cancer agent.

Objective:

In this study, the effects of laser and ultrasound irradiation with Se-PEG-Cur nanoparticles were investigated on melanoma cancer.

Material and Methods:

In this experimental study, nanoparticles of selenium-polyethylene glycol-curcumin (Se-PEG-Cur) were synthesized, and their UV-vis absorption, particle size, zeta potential and photothermal conversion efficiency were determined. Se-PEG-Cur was then introduced as a novel 808-nm laser light absorbing agent as well as ultrasound (US) wave for treatment of C540 (B16/F10) cancer cells. Also, ROS generation in C540 (B16/F10) cancer cells was measured upon PTT and SDT using Se-PEG-Cur.

Results:

Mean size, zeta potential and photothermal conversion efficiency of Se-PEG-Cur were obtained as ~300 nm, 42.7 mV and 16.7%, respectively. Cell viability upon irradiation of the laser light or US waves with 100 µg mL^-1 Se-PEG-Cur were decreased to 33.9 and 22.9%, respectively.

Conclusion:

Intracellular ROS detection indicated that dual PTT and SDT in the presence of Se-PEG-Cur induced the highest ROS production. Se-PEG-Cur was therefore introduced as an absorbing agent of both laser light and US waves for cancer treatment.

A MoS2@Ti3C2Tx MXene hybrid-based electrochemical aptasensor (MEA) for sensitive and rapid detection of Thyroxine

In the present study, a MoS₂@Ti₃C₂T_x MXene hybrid-based electrochemical aptasensor (MEA) was introduced for sensitive and rapid quantification of Thyroxine (T4). T4 is a crucial hormone and plays a key role in various body functions. Therefore, there is high demand for an accurate, sensitive, and rapid method for the detection of T4. To construct the aptasensor, a nano-hybrid (NH) consisting of Ti₃C₂T_x MXene and MoS₂ nanosheets (NS) was synthesized, and applied to a carbon electrode surface, followed by the electroplating of gold nanostructures (GN). The smart combination of Ti₃C₂T_x MXene and MoS₂NS enhanced the physiochemical properties of the electrode surface, as well as provided a building block to form 3D GN. The 3D architecture of the GN offered a unique substrate to capture numerous T4 aptamer molecules, which consequently amplified the signal by nearly 6-fold. The MEA quantified thyroxine with a limit of detection (LOD) of 0.39 pg/mL over a dynamic range ((7.8 × 10^-1) to (7.8 × 10⁶)) pg/mL within 10 min. Moreover, the MEA successfully detected T4 in human serum samples. Lastly, the results obtained from the aptasensor were compared with those from the ELISA standard method. The comparative analysis showed good agreement between the two methods.

Bimetallic nickel-ferrite nanorod particles: greener synthesis using rosemary and its biomedical efficiency

Nickel-ferrite (NiFe₂O₄) nanorods particles (NRP) was biosynthesised for the first time by the Rosemary Extract. The NRP was fully characterised, including the type, nanostructure and physicochemical properties of using XRD, HRTEM, FeSEM, XPS, FTIR and VSM. TEM confirmed rod-shaped nano-sized particles with average sizes ranging from 10 nm to 28 nm. The EDAX Analysis showed the presence of iron, nickel, oxygen, and carbon. XRD analysis confirmed the synthesis of NiFe₂O₄ crystals. XPS curves showed photoelectron for iron, oxygen and nickel. EDS showed the atomic, weight percentages ratios of Ni(12%): Fe(24%) and: O(48) are close to the theoretical value (Ni: Fe:O = 1:2:4), of bimetallic magnetic NiFe₂O₄ NRP. NiFe₂O₄ NRP had cytotoxicity effect on MCF-7 cells survival which suggests that NiFe₂O₄ NRP can be used as a new class of anticancer agent in design novel cancer therapy research.

Seed-mediated Electrochemically Developed Au Nanostructures with Boosted Sensing Properties: An Implication for Non-enzymatic Glucose Detection

A new approach has been developed to improve sensing performances of electrochemically grown Au nanostructures (AuNSs) based on the pre-seeding of the electrode. The pre-seeding modification is simply carried out by vacuum thermal deposition of 5 nm thin film of Au on the substrate followed by thermal annealing at 500 °C. The electrochemical growth of AuNSs on the pre-seeded substrates leads to impressive electrochemical responses of the electrode owing to the seeding modification. The dependence of the morphology and the electrochemical properties of the AuNSs on various deposition potentials and times have been investigated. For the positive potentials, the pre-seeding leads to the growth of porous and hole-possess networks of AuNSs on the surface. For the negative potentials, AuNSs with carved stone ball shapes are produced. The superior electrode was achieved from AuNSs developed at 0.1 V for 900 s with pre-seeding modification. The sensing properties of the superior electrode toward glucose detection show a high sensitivity of 184.9 µA mM⁻¹ cm⁻², with a remarkable detection limit of 0.32 µM and a wide range of linearity. The excellent selectivity and reproducibility of the sensors propose the current approach as a large-scale production route for non-enzymatic glucose detection.

Greener synthesis of Rod Shaped Zinc Oxide Nanoparticles using Lilium ledebourii tuber and evaluation of their Leishmanicidal activity

Background

Nanoparticles (NPs) with unique chemical and physical properties can be used for therapeutic purposes because of their strong antimicrobial activates. Nanoparticles have been used as an antimicrobial agents to inhibit microbial growth.

Objectives

In view of the strong antimicrobial activity of nanoparticles, the biogenic synthesis and leishmanicidal activity of rod-shaped zinc oxide (R-ZnO) nanoparticles was explored using Lilium ledebourii tuber extract.

Materials and Methods

The ensuing nanoparticles are characterized by UV-visible spectroscopy, X-ray diffraction and transmission electron microscopy and their leishmanicidal activity evaluated against the Leishmania major (L. major) by MTT assay.

Results

The R-ZnO nanoparticles displayed excellent leishmanicidal activity against the L. major as they significantly inhibited the amastigotes. The IC₅₀ values of R-ZnO nanoparticles being ~ 0.001 mg.mL^-1. R-ZnO nanoparticles can inhibit L. major growth in a dose-dependent manner under in vitro conditions.

Conclusion

A simple, low-cost feasible and eco-friendly procedure was developed for biosynthesis of R-ZnO nanoparticles using natural bioresource that can inhibit human parasite cells growth in a dose-dependent manner under in vitro conditions.

An electrochemical peptide-based biosensor for the Alzheimer biomarker amyloid-β(1-42) using a microporous gold nanostructure

Alzheimer's disease (AD) is connected to aggregation of amyloid-β (Aβ) peptide and formation of insoluble plaques in the brain. Aβ level can be monitored as an AD early diagnosis route. In this study, an irregular shaped microporous gold nanostructure with a typical size of 150 × 250 nm was electrodeposited on a polycrystalline gold surface at 0 mV (vs. AgCl) using sodium alendronate. The nanostructure was then characterized by field-emission scanning electron microscopy. An electrochemical peptide-based biosensor was fabricated by immobilizing an Aβ_(1-42)-binding peptide on the gold nanostructure. Binding of Aβ_(1-42) by the peptide was followed electrochemically using ferro/ferricyanide as a redox probe. Differential pulse voltammograms in a potential range of 0-500 mV (vs. AgCl) with typical peak potentials at 224 mV are linear in the 3-7000 pg mL^-1 Aβ_(1-42) concentration range, with a 0.2 pg mL^-1 detection limit. The biosensor is free of interferences and was applied to the quantitation of Aβ_(1-42) in artificial cerebrospinal fluid and spiked serum samples. Graphical abstractSchematic presentation of an immobilized amyloid-β_(1-42)-specific peptide on the surface of a microporous gold nanostructure to fabricate an electrochemical biosensor for early diagnosis of Alzheimer's disease. Aβ_(1-42) capturing by the peptide led to repulsion of ferrocyanide/ferricyanide redox couple.

Electrospun tin (IV) oxide nanofiber based electrochemical sensor for ultra-sensitive and selective detection of atrazine in water at trace levels

Atrazine, a class 3a carcinogen, is a pesticide of chloro triazine family and is known to severely affect the human endocrine system upon consumption. The toxic effects of atrazine cause damage not only to the humans but also to animals and plants. In lieu of the detrimental effects of atrazine on environment, it is essential to develop a sensor platform capable of its detection in water. Here, we propose ultrasensitive electrochemical detection of atrazine using electrospun SnO₂ nanofibers. In this study, the nanofibers have been characterized using Field Emission Spectroscopy, X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), UV-Vis-NIR spectroscopy and Fourier transform infrared spectroscopy (FTIR). Using a label-free transduction, we have detected atrazine in fairly low concentrations, with the limit of detection being 0.9 zM and the sensitivity being 4.11 (μA/μM)/cm², in a wide dynamic detection range varying from 1 zM to 1 μM. Furthermore, we have reported atrazine detection in trace levels in spiked real time water samples, which is an essential step in ensuring that the sensing platform can be deployed for practical applications. In addition to this, the sensor exhibits excellent selectivity, reasonable stability (when stored at 4 °C), and good interference-resistance.

Detection of Brucella abortus by a platform functionalized with protein A and specific antibodies IgG

Oriented immobilization of antibodies on a sensor surface is critical for enhancing both the antigen-binding capacity and the sensitivity of immunosensors. In this study, we describe a strategy to adsorb immunoglobulin G (IgG) anti-Brucella antibodies onto a silicon surface, oriented by protein A obtained from Staphylococcus aureus (SpA). X-ray photoelectron spectroscopy and atomic force microscopy were used to characterize topographically, morphologically, and chemical changes of the sensor functionalization. The activity of the biosensor was assessed by confocal microscopy, scanning electronic microscopy, and bacteria capture assays (BCA). According to the BCA, the efficiency of Brucella abortus detection with the SpA-IgG anti Brucella biosensor was three-fold higher than that of the random orientated IgG anti Brucella biosensor. The limit of detection was 1 × 10⁶ CFU/ml. These data show that the orientation of antibodies immobilization is crucial to developing immunosensors for bacterial antigen detection as Brucella spp and improve its sensibility level. Functionalization with protein A increases Brucella detection by an antibody-coated surface. Functionalized silicon surface for Brucella detection was characterized by atomic force microscopy, X-ray photoelectron spectroscopy and confocal microscopy.

Detecting Biothreat Agents: From Current Diagnostics to Developing Sensor Technologies

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

Electrochemical quantitation of Leishmania infantum based on detection of its kDNA genome and transduction of non-spherical gold nanoparticles

Detecting and monitoring the pathogens with high selectivity and sensitivity is critical for public health. In the present study, we demonstrated a specific analytical strategy for sensitive detection of Leishmania infantum genome. The developed sensor utilized toluidine blue as a hybridization indicator and a Leishmania infantum-specific capture DNA sequence immobilized on a high-surface area gold nanostructure as an electrochemical transducer. The produced analytical response was based on the hybridization of the single-stranded DNA from the target with the immobilized DNA sequence at the electrode surface. The developed DNA sensor in this study was successfully employed to detect a synthetic Leishmania infantum target sequence in a wide concentration range from 1 × 10^-18 to 1 × 10^-10 mol L^-1 with a detection limit of 0.2 amol L^-1 with the ability to discriminate the target sequence from mismatched sequences. Moreover, the designed DNA sensor showed a good reproducibility and stability during repeated regeneration and hybridization cycles. The DNA sensor could detect Leishmania infantum genome in a wide concentration range from 15 to 50 ng μL^-1 with a detection limit of 29 ng μL^-1. Furthermore, clinical trials confirmed the applicability of the developed DNA sensor for practical applications.

Biosynthesis of Ag nanoparticles using Salicornia bigelovii and its antibacterial activity

BACKGROUND AND AIM

In recent years, the field of nanotechnology has become the most active area of research in modern material science. While many chemical- as well as physical methods are also used, green synthesis of nanoparticles is becoming the most evolved method of synthesis. In this study, we synthesized silver nanoparticles from the seed extract of Salicornia bigelovii.

METHODS

This experimental study was conducted from December 2017 to January 2018 in Kerman University of Medical Sciences, Kerman, Iran. The effects of two concentrations (1m M and 4mM) on the synthesis of nanoparticles were studied. Characterizations were done using different methods including ultraviolet (UV) visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Antibacterial activity of Ag nanoparticles against Staphylococcus aureus and Escherichia coli was studied using microdilution method. The data were analyzed using Probit test in SPSS (Version 20, USA).

RESULTS

Formation of the AgNPs was confirmed by surface plasmon spectra using UV-Vis spectrophotometer and absorbance peaks at 434 nm. The FTIR spectra showed the possible role of the functional group like carbonyl groups in reduction of silver ions to silver nanoparticles. The XRD analysis showed that the synthesized silver nanoparticles are of face-centered cubic structure. The TEM showed the formation of silver nanoparticles ranging in diameter from 1 to 50 nm. The minimal inhibitory concentration and minimal bactericidal concentration of AgNPs were determined for both S. aureus and E. coli 6.25 and 12.5 μg/mL, respectively.

CONCLUSION

An environmentally friendly approach is more affordable than chemical methods. Physicochemical approaches can be harmful to the environment and to human health. Thus, the green synthesis methods are simple, less expensive, and can cut consumption of energy; they can be used for synthesis of fixed nanoparticles with preferred shape and size, without the use of toxic chemical agents.

Cytotoxicity, leishmanicidal, and antioxidant activity of biosynthesised zinc sulphide nanoparticles using Phoenix dactylifera

The synthesis of zinc sulphide nanoparticles (ZnS NPs) using a green approach was explored. The resulting nanoparticles (NPs) were characterised by UV–vis spectroscopy, scanning and transmission electron microscopy, X‐ray diffraction and Fourier transform infrared spectroscopy. The leishmanicidal, cytotoxic and antioxidant activity of the resulting synthesised ZnS NPs (<70 nm) were evaluated against Leishmania major (L. major ) promastigotes and amastigotes by MTT assay and using a macrophage model. The ZnS NPs were able to counteract the effects of oxidative metabolites as demonstrated by the oxidant activity. The IC50 value of butylated hydroxyanisole was 26.04 µg/ml as compared with the IC50 for ZnS NPs (90.95 µg/ml). The NPs displayed no cytotoxicity for the murine macrophaghes as the selectivity index (SI) fell into the safety range (SI ≥ 10). These nanomaterials exhibited good antileishmanial activity against the L. major stages that were comparable to that of Glucantime, the drug of choice. The IC50 values of ZnS NPs and Glucantime against amastigotes were 11.59 ± 2.51 and 4.95 ± 2.51 μg/ml, respectively. The IC50 values for ZnS NPs and Glucantime versus promastigote were 29.81 ± 3.15 and 14.75 ± 4.05 μg/ml, respectively. Further investigation is essential to explore the biological effects of ZnS NPs on animal and/or clinical models.

A signal-on built in-marker electrochemical aptasensor for human prostate-specific antigen based on a hairbrush-like gold nanostructure

A green electrodeposition method was firstly employed for the synthesis of round hairbrush-like gold nanostructure in the presence of cadaverine as a size and shape directing additive. The nanostructure which comprised of arrays of nanospindles was then applied as a transducer to fabricate a signal-on built in-marker electrochemical aptasensor for the detection of human prostate-specific antigen (PSA). The aptasensor detected PSA with a linear concentration range of 0.125 to 128 ng mL-1 and a limit of detection of 50 pg mL-1. The aptasensor was then successfully applied to detect PSA in the blood serum samples of healthy and patient persons.

A label-free, PCR-free and signal-on electrochemical DNA biosensor for Leishmania major based on gold nanoleaves

Detection of leishmaniasis is important in clinical diagnoses. In the present study, identification of Leishmania parasites was performed by a label-free, PCR-free and signal-on ultrasensitive electrochemical DNA biosensor. Gold nanoleaves were firstly electrodeposited by an electrodeposition method using spermidine as a shape directing agent. The biosensor was fabricated by immobilization of a Leishmania major specific DNA probe onto gold nanoleaves, and methylene blue was employed as a marker. Hybridization of the complementary single stranded DNA sequence with the biosensor under the selected conditions was then investigated. The biosensor could detect a synthetic DNA target in a range of 1.0×10^-10 to 1.0×10^-19molL^-1 with a limit of detection of 1.8×10^-20molL^-1, and genomic DNA in a range of 0.5-20ngμL^-1 with a limit of detection of 0.07ngμL^-1. The biosensor could distinguish Leishmania major from a non-complementary-sequence oligonucleotide and the tropica species with a high selectivity. The biosensor was applicable to detect Leishmania major in patient samples.

Label-free electrochemical aptasensing of the human prostate-specific antigen using gold nanospears

Gold nanospears were electrodeposited with the assistance of arginine as a soft template and precise selection of experimental parameters. The nanospears were then employed as a transducer to immobilize an aptamer of prostate-specific antigen (PSA) and fabrication of a label-free electrochemical aptasensor. The aptasensor was employed for the detection of PSA with a linear concentration range of 0.125-200ngmL(-1) and a limit of detection of 50pgmL(-1). The aptasensor was successfully applied to detect PSA in blood serum samples of healthy and patient persons.