Mercury (II) sensing using a simple turn-on fluorescent graphene oxide based aptasensor in serum and water samples

A simple, highly sensitive, and selective fluorometric aptasensing platform based on aptamer and graphene oxide (GO) is proposed for the determination of mercury (II) ion (Hg2+). In the designed assay, two aptamer probes, a carboxy-fluorescein (FAM) labeled aptamer (aptamer A) and its complementary (aptamer B) with partial complement containing several mismatches and GO as the quencher were used. In the absence of Hg2+, both A and B aptamers were adsorbed on the surface of GO by π-π-stacking, leading to fluorescence quenching of FAM due to fluorescence resonance energy transfer (FRET). Upon exposure to Hg2+, the A and B aptamer strands bind Hg2+ and form T-Hg2+-T complexes, leading to the formation of a stable double-stranded aptamer. The double-stranded aptamer is detached from the GO surface, resulting in the recovery of FAM fluorescence. The fluorescence intensity (FI) of the developed sensor was correlated with the Hg2+ concentration under optimized experimental conditions in two wide linear ranges, even in the presence of 10 divalent cations as interferences. The linear ranges were obtained from 200.0 to 900.0 fM and 5.0 to 33.0 pM, a limit of detection (LOD) of 106.0 fM, and a limit of quantification (LOQ) of 321.3 fM. The concentration of Hg2+ was determined in five real samples containing three water and two serum samples, using spiking and standard addition methods and the results were compared with the spiked amounts and atomic absorption (AAS) as standard method respectively, with acceptable recoveries. Furthermore, in the standard addition method, to overcome the effects of matrix influence of real samples in quantitative predictions, the excitation-emission matrix (EEM) data for samples was simultaneously analyzed by multivariate curve resolution with alternating least squares (MCR-ALS) as a second-order standard addition method (SOSAM).

Smart Wearable Nanopaper Patch for Continuous Multiplexed Optical Monitoring of Sweat Parameters

Notwithstanding the substantial progress in optical wearable sensing devices, developing wearable optical sensors for simultaneous, real-time, and continuous monitoring of multiple biomarkers is still an important, yet unmet, demand. Aiming to address this need, we introduced for the first time a smart wearable optical sensor (SWOS) platform combining a multiplexed sweat sensor sticker with its IoT-enabled readout module. We employed our SWOS system for on-body continuous, real-time, and simultaneous fluorimetric monitoring of sweat volume (physical parameter) and pH (chemical marker). Herein, a variation in moisture (5-45 μL) or pH (4.0-7.0) causes a color/fluorescence change in the copper chloride/fluorescein immobilized within a transparent chitin nanopaper (ChNP) in a selective and reversible manner. Human experiments conducted on athletic volunteers during exercise confirm that our developed SWOS platform can be efficiently exploited for smart perspiration analysis toward personalized health monitoring. Moreover, our system can be further extended for the continuous and real-time multiplexed monitoring of various biomarkers (metabolites, proteins, or drugs) of sweat or other biofluids (for example, analyzing exhaled breath by integrating onto a facemask).

Lateral Flow Assay: A Summary of Recent Progress for Improving Assay Performance

Lateral flow tests are one of the most important types of paper-based point-of-care (POCT) diagnostic tools. It shows great potential as an implement for improving the rapid screening and management of infections in global pandemics or other potential health disorders by using minimally expert staff in locations where no sophisticated laboratory services are accessible. They can detect different types of biomarkers in various biological samples and provide the results in a little time at a low price. An important challenge regarding conventional LFAs is increasing their sensitivity and specificity. There are two main approaches to increase sensitivity and specificity, including assay improvement and target enrichment. Assay improvement comprises the assay optimization and signal amplification techniques. In this study, a summarize of various sensitivity and specificity enhancement strategies with an objective evaluation are presented, such as detection element immobilization, capillary flow rate adjusting, label evolution, sample extraction and enrichment, etc. and also the key findings in improving the LFA performance and solving their limitations are discussed along with numerous examples.

Nitrogen and sulfur co-doped carbon quantum dots fluorescence quenching assay for detection of mercury (II)

Mercury is a highly toxic and potentially bioaccumulative heavy metal ion that can cause severe health problems in humans even at very low concentrations. Thus, the development of a simple, rapid, and sensitive assay for the effective detection of mercury ions at trace levels is of great importance. Here, nitrogen and sulfur co-doped carbon quantum dots (N,S-CQD) were synthesized by a simple hydrothermal treatment of chitosan in the presence of thiourea and citric acid with a quantum yield (QY) up to 33.0 % and used as a selective fluorescent probe to detect mercury ions (Hg²⁺). The effect of pH, ionic strength, and time on the fluorescence intensity of N,S-CQD were investigated and optimized. The synthesized N,S-CQD showed ultrasensitive ability to detect Hg²⁺ ions in the water samples, also in the presence of 11 interfering metal ions, with a low detection limit (∼4 nM) over a wide linear range from ∼5-160 nM. The sensing performance of N,S-CQD probe in real sample applications was evaluated by the detection of Hg²⁺ in lake water samples, which confirmed its potential application in environmental analysis.

Toward waterborne protozoa detection using sensing technologies

Drought and limited sufficient water resources will be the main challenges for humankind during the coming years. The lack of water resources for washing, bathing, and drinking increases the use of contaminated water and the risk of waterborne diseases. A considerable number of waterborne outbreaks are due to protozoan parasites that may remain active/alive in harsh environmental conditions. Therefore, a regular monitoring program of water resources using sensitive techniques is needed to decrease the risk of waterborne outbreaks. Wellorganized point-of-care (POC) systems with enough sensitivity and specificity is the holy grail of research for monitoring platforms. In this review, we comprehensively gathered and discussed rapid, selective, and easy-to-use biosensor and nanobiosensor technologies, developed for the early detection of common waterborne protozoa.

Three-layered PCL-collagen nanofibers containing melilotus officinalis extract for diabetic ulcer healing in a rat model

Active wound dressing with physicochemical and biological characteristics is more effective in healing diabetic foot ulcer (DFU). In this study, a 3-layer electrospun nanofiber wound dressings was fabricated, while its outer, middle and inner layers of the scaffold were made of PCL, PCL/collagen and collagen nanofibers, respectively. Various amounts of Melilotus officinalis extract were also loaded in the collagen nanofibers as a biologically active compound. The diameter and morphology of the obtained nanofibers were investigated by scanning electron microscopy (SEM) and FT-IR spectroscopy to analyse the composition of prepared dressings. The efficacy of the fabricated dressings as wound healing agent was assessed in streptozotocin-induced diabetic rats. The results demonstrated that the mean diameter of nanofibers are 373 ± 179 nm, 266 ± 108 nm, 160 ± 52 nm, and 393 ± 131 nm for PCL, PCL/collagen, pure collagen, and collagen nanofibers containing 0.08 g extract, respectively. The histo-pathology and histomorphometry assessments demonstrate the herbal extract-loaded electrospun dressings (especially containing 0.08 g of the extract) are promising in improving the diabetic ulcer healing. Our results indicated that the combination of drug did not compromise the physicochemical characteristics of wound dressing, while improving its biological activities.

Smartphone-Based Electrochemiluminescence for Visual Simultaneous Detection of RASSF1A and SLC5A8 Tumor Suppressor Gene Methylation in Thyroid Cancer Patient Plasma

Visual one-step simultaneous detection of low-abundance methylation is a crucial challenge in early cancer diagnosis in a simple manner. Through the design of a closed split bipolar electrochemistry system (BE), detection of promoter methylation of tumor suppressor genes in papillary thyroid cancer, RASSF1A and SLC5A8, was achieved using electrochemiluminescence. For this purpose, electrochemiluminescence of luminol loaded into the Fe₃O₄@UiO-66 and gold nanorod-functionalized graphite-like carbon nitride nanosheet (AuNRs@C₃N₄ NS), separately, on the anodic and cathodic pole bipolar electrodes (BPEs) in two different chambers of a bipolar cell were recorded on a smartphone camera. To provide the same electric potential (ΔE_elec) through the BPEs to conduct simultaneous light emission, as well as to achieve higher sensitivity, anodic and cathodic poles BPEs were separately connected to ruthenium nanoparticles electrodeposited on nitrogen-doped graphene-coated Cu foam (fCu/N-GN/RuNPs) to provide a hydrogen evolution reaction (HER) and polycatechol-modified reduced graphene oxide/pencil graphite electrode (PC-rGO/PGE) to provide electrooxidation of hydrazine. Moreover, taking advantages of the strong cathodic ECL activity due to the roles of AuNRs, as well as the high density of capture probes on the UiO-66 and Fe₃O₄ roles in improving the signal-to-background ratio (S/B) in complicated plasma media, a sensitive visual ECL immunosensor was developed to detect two different genes as model target analytes in patient plasma samples. The ability of discrimination of methylation levels as low as 0.01% and above 90% clinical sensitivity in thyroid cancer patient plasma implies that the present strategy is able to diagnose cancer early, as well as monitor responses of patients to therapeutic agents.

Electrochemical immunosensor for determination of cardiac troponin I using two-dimensional metal-organic framework/Fe3O4-COOH nanosheet composites loaded with thionine and pCTAB/DES modified electrode

Cardiac troponin-I (CTnI) is one of the most popular biomarkers which can be utilized for the diagnosis and control of acute myocardial infarction in clinical practice. Here, a sandwich-type electrochemical immunosensor has been established using the zinc-based metal-organic framework/Fe₃O₄-COOH/thionine labeled anti-CTnI monoclonal antibody (Ab₁-Zn-MOF/Fe₃O₄-COOH/Thi) nanocomposite as signaling molecule and a polymer film of cetyltrimethylammonium bromide (pCTAB) in the presence of choline chloride-urea deep eutectic solvent (DES) and anti-CTnI polyclonal antibody (Ab₂) as immobilization substance of detecting surface. The porous ultrathin layers of Zn-MOF nanosheets successfully prepare a well-defined structure for Fe₃O₄-COOH electrocatalyst and Thi within a certain two dimensional (2D) regions, which enhances electrochemical reduction of Thi. The Ab₁-Zn-MOF/Fe₃O₄-COOH/Thi nanocomposites were introduced to CTnI in the specimen and on the surface of pCTAB/DES-Au-SPE quantitative determination of CTnI was achieved using differential pulse voltammetry after sandwiching the CTnI target between Ab₁-nanocomposite and Ab₂ which was encapsulated into the pCTAB/DES-Au-SPE. This immunosensor indicated the appropriate assay performance for CTnI with the detection range of 0.04 ng mL^-1 to 50 ng mL^-1 and the limit of detection of 0.0009 ng mL^-1. This study provides convenient plan for sensitive detection of bioanalytes and opens a path for the establishment of user-friendly and cost-effective device.

Simultaneous Detection of SARS-CoV-2 IgG/IgM Antibodies, Using Gold Nanoparticles-Based Lateral Flow Immunoassay

The novel coronavirus disease (COVID-19), known as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), exhibits a strong human-to-human transmission infectivity and could cause acute respiratory infections. Therefore, simple and rapid serological testing is urgently needed to recognize positive cases. In this study, a point-of-care serological test based on lateral flow immunoassay (LFIA) was developed and its application for the simultaneous detection of IgM/IgG antibodies against SARS-CoV-2 was evaluated. The recombinant SARS-CoV-2 antigens were conjugated to the produced colloidal gold nanoparticles and used as the detection reagent. This test required only 10-15 minutes to achieve simultaneous qualitative detection of IgM/IgG antibodies specific to SARS-CoV-2 in 20 μL of serum or plasma samples. The clinical performance and reliability of the assay were evaluated by performing the test with 60 samples and comparing the results of these tests with those obtained via real-time polymerase chain reaction. The sensitivity and specificity of our assay were defined to be 90% and 96.6%, respectively. The presented LFIA was sufficiently sensitive and accurate to be used for the rapid diagnosis of coronavirus disease 2019 in laboratories or in patient care settings, particularly in emergency conditions, in which many samples require to be evaluated on time.

Electrochemiluminescence paper-based screen-printed electrode for HbA1c detection using two-dimensional zirconium metal-organic framework/Fe3O4 nanosheet composites decorated with Au nanoclusters

Glycated hemoglobin (HbA1c) is one of the most popular biomarkers which can be utilized for the diagnosis and control of diabetes in clinical practice. In this study, a sandwich paper-based electrochemiluminescence (ECL) biosensor has been developed using the zirconium metal-organic framework/Fe₃O₄(trimethyl chitosan)/gold nanocluster (Zr-MOF/Fe₃O₄(TMC)/AuNCs) nanocomposite as tracing tag to label anti-HbA1c monoclonal antibody and reduced graphene oxide (rGO) as immobilization platform of sensing element. The screen-printed electrodes (SPEs) were constructed and modified by sputtering a thick layer of gold on the paper substrate, followed by electrochemical reduction of aminophenylboronic acid (APBA)-functionalized GO to rGO/APBA, respectively. Different types of surface analysis methods were applied to characterize the Zr-MOF/Fe₃O₄(TMC)/AuNCs nanomaterials fabricated. Finally, antibody-labeled Zr-MOF/Fe₃O₄(TMC)/AuNCs nanocomposites were subjected to HbA1c in the sample and on the paper-based SPE. Quantitative measurement of HbA1c was performed using ECL and cyclic voltammetry (CV) over a potential range of - 0.2 to 1.7 V vs gold reference electrode with a sweep rate of 0.2 V.s^-1 in the presence of triethylamine as a co-reactant after sandwiching the HbA1c target between antibody and APBA on the sensing area. This immunosensor demonstrated the desirable assay performance for HbA1c with a wide response range from 2 to 18% and a low detection limit (0.072%). This new strategy provides an effective method for high-performance bioanalysis and opens avenues for the development of high-sensitive and user-friendly device. Graphical abstract.

Point-of-care cancer diagnostic devices: From academic research to clinical translation

Early and timely diagnosis of cancer plays a decisive role in appropriate treatment and improves clinical outcomes, improving public health. Significant advances in biosensor technologies are leading to the development of point-of-care (POC) diagnostics, making the testing process faster, easier, cost-effective, and suitable for on-site measurements. Moreover, the incorporation of various nanomaterials into the sensing platforms has yielded POC testing (POCT) platforms with enhanced sensitivity, cost-effectiveness and simplified detection schemes. POC cancer diagnostic devices provide promising platforms for cancer biomarker detection as compared to conventional in vitro diagnostics, which are time-consuming and require sophisticated instrumentation, centralized laboratories, and experienced operators. Current innovative approaches in POC technologies, including biosensors, smartphone interfaces, and lab-on-a-chip (LOC) devices are expected to quickly transform the healthcare landscape. However, only a few cancer POC devices (e.g. lateral flow platforms) have been translated from research laboratories to clinical care, likely due to challenges include sampling procedures, low levels of sensitivity and specificity in clinical samples, system integration and signal readout requirements. In this review, we emphasize recent advances in POC diagnostic devices for cancer biomarker detection and discuss the critical challenges which must be surmounted to facilitate their translation into clinical settings.

Point-of-care biosensors in medicine: a brief overview of our achievements in this field based on the conducted research in EMRI (endocrinology and metabolism research Institute of Tehran University of medical sciences) over the past fourteen years

The growing demand of diagnostic tools with enhanced analytical characteristics in term of sensitivity, selectivity, and low response time has encouraged researches to conduct their research towards development of point-of-care (POC) biosensors. POC diagnostic devices are powerful tools for detection, diagnosis, and monitoring of diseases at its initial stage. The above characteristics encouraged us to conduct active multidisciplinary and collaborative research oriented towards the design and development of POC sensing systems. Here, we present a brief overview of our recent achievement in the field of biomedical POC devices implemented in paper based microfluidic and screen printing electrodes and discuss the critical limitations that need to be surmounted to facilitate their translation into clinical practice in the future.

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.

Biosensor design using an electroactive label-based aptamer to detect bisphenol A in serum samples

A new and simple procedure was applied to detect bisphenol A (BPA) based on a BPA aptamer and its complementary strand (Comp. Str.). An electrode was modified with a mixture of carboxylated multiwalled carbon nanotubes and chitosan. The Comp. Str. was immobilized on a modified-glassy carbon electrode (GCE) surface via covalent binding. After the incubation of the aptamer with the electrode surface, it could interact with the Comp. Str. In the presence of BPA, its aptamer will interact with the analyte, resulting in some changes in the configuration and leading to separation from the electrode surface. Due to the attached ferrocene (Fc) group on the 50 head of the aptamer, the redox current of Fc has reduced. This aptasensor can sense the level of BPA in the linear range of 0.2-2 nM, with a limit of detection of 0.38 nM and a sensitivity of 24.51 lA/μM. The proposed aptasensor showed great reliability and selectivity. The acceptable selectivity is due to the specificity of BPA binding to its aptamer. The serum sample was used as a real sample; the aptasensor was able to effectively recover the spiked BPA amounts. It can on-site monitor the BPA in serum samples with acceptable recoveries.

Electrochemical sensors and biosensors based on the use of polyaniline and its nanocomposites: a review on recent advances

Polyaniline and its composites with nanoparticles have been widely used in electrochemical sensor and biosensors due to their attractive properties and the option of tuning them by proper choice of materials. The review (with 191 references) describes the progress made in the recent years in polyaniline-based biosensors and their applications in clinical sensing, food quality control, and environmental monitoring. A first section summarizes the features of using polyaniline in biosensing systems. A subsequent section covers sensors for clinical applications (with subsections on the detection of cancer cells and bacteria, and sensing of glucose, uric acid, and cholesterol). Further sections discuss sensors for use in the food industry (such as for sulfite, phenolic compounds, acrylamide), and in environmental monitoring (mainly pesticides and heavy metal ions). A concluding section summarizes the current state, highlights some of the challenges currently compromising performance in biosensors and nanobiosensors, and discusses potential future directions. Graphical abstract Schematic presentation of electrochemical sensor and biosensors applications based on polyaniline/nanoparticles in various fields of human life including medicine, food industry, and environmental monitoring. The simultaneous use of suitable properties polyaniline and nanoparticles can provide the fabrication of sensing systems with high sensitivity, short response time, high signal/noise ratio, low detection limit, and wide linear range by improving conductivity and the large surface area for biomolecules immobilization.

Modified methylated DNA immunoprecipitation protocol for noninvasive prenatal diagnosis of Down syndrome

AIM

Methylated DNA immunoprecipitation real-time quantitative polymerase chain reaction (MeDIP-real-time qPCR) has been introduced as noninvasive prenatal test that has shown absolute detection rate in the screening of Down syndrome. Herein, we aimed to propose a novel modification of MeDIP-qPCR and assess its potential to alleviate the overall cost of the test, being used in very early weeks of pregnancy, and develop it to a noninvasive prenatal diagnosis biosensor in future researches.

METHODS

Cell-free fetal DNA (cffDNA) isolated from 60 pregnant women, including 29 normal and 31 trisomy 21 pregnancies, were analyzed using proposed MeDIP protocol. Enriched methylated DNA sequences were amplified through real-time qPCR using eight fetal-specific primer pairs. The status of samples was determined through the calculation of D-value with the cutoff point of zero.

RESULTS

The sensitivity and specificity of the MeDIP protocols using nanoparticles were 100% and 100%, respectively.

CONCLUSION

Remarkable decrease in the price of MeDIP test per each patient would be a reasonable factor to confirm it on larger sample size. Moreover, the high detection rate of screening and the availability of the required instruments around the world make satisfactory reasons to be tested in earlier weeks of pregnancy, thanks to the high sensitivity of gold shell nanoparticles.

A novel intracellular pH-responsive formulation for FTY720 based on PEGylated graphene oxide nano-sheets

OBJECTIVE

This study was performed to investigate a novel pH-responsive nanocarrier based on modified nano graphene oxide (nGO) to promote the acid-triggered intracellular release of a poorly soluble drug, FTY720.

METHODS

To synthesize a drug conjugated to modified nGO, first the polyethylene glycol (PEG) was conjugated to nGO, then the produced PEG-nGO was functionalized with the anticancer drug, FTY720, through amide bonding. It was characterized by the scanning electron microscopy (SEM), the atomic force microscopy (AFM), the Fourier transform infrared (FTIR) spectroscopy and the UV-vis spectroscopy. In vitro drug release of the FTY720-conjugated PEG-nGO was evaluated at pH 7.4 and 4.6 PBS at 37 °C. Furthermore, the antineoplastic action of unloaded and drug-loaded carrier against the human breast adenocarcinoma cell line MCF7 was explored using MTT and BrdU assays.

RESULTS

Characterization methods indicated successful drug deposition on the surface of nGO. In vitro, drug release results revealed a significantly faster release of FTY720 from PEG-nGO at acidic pH, compared with physiological pH. The proliferation assays proved that the unloaded nGO had no significant cytotoxicity against MCF7 cells, while free FTY720- and FTY720-loaded PEG-nGO had an approximately equal cytotoxic effect on the MCF7 cells. It was found that the extended release characteristic of FTY720 was well fitted to Korsmeyer-Peppas model and the release profile of FTY720 from PEG-nGO is diffusion controlled.

CONCLUSION

PEGylated GO can act as a pH-responsive drug carrier to improve the efficacy of anticancer drug delivery.

Growth Factor-Loaded Nano-niosomal Gel Formulation and Characterization

Controlled delivery of signaling factors could be a great approach in the tissue engineering field. Nano-niosomal drug delivery systems offer numerous advantages for this purpose. The present study reports the formulation and evaluation of a growth factor (GF)-loaded nano-niosome-hydrogel composite for GF delivery to modulate cell behavior. Niosomes were prepared, using span 60 surfactant with cholesterol (CH) in diethyl ether solvent, by reverse-phase evaporation technique. Basic fibroblast growth factor (bFGF) and bovine serum albumin (BSA) were loaded simultaneously and the final suspension was embedded into agarose hydrogel. Particle size, vesicle morphology, protein entrapment efficiency (EE), and release profile were measured by dynamic light scattering (DLS) nanoparticle size analyzer, transmission electron microscopy (TEM) and NanoDrop spectrophotometry methods, respectively. The release and performance of bFGF were revealed via human umbilical vein endothelial cell (HUVEC) proliferation using microscopy imaging and MTT assay. Nano-niosomes had an average particle size of 232 nm and had encapsulated 58% of the total proteins present in the suspension. bFGF-BSA-loaded niosomal gel considerably enhanced HUVEC proliferation. This GF-loaded niosomal hydrogel could be a potent material in many biomedical applications including the induction of angiogenesis in tissue engineering.

Formulation and Characterization of Bovine Serum Albumin-Loaded Niosome

Niosomal vesicle, as a unique novel drug delivery system, is synthesized by non-ionic surfactants. Both hydrophilic and lipophilic drugs and also biomacromolecular agents, such as peptides and proteins can be encapsulated in this vesicular particle. Regarding polypeptide-based component loading, and delivery potential of the niosome, some valuable studies have been conducted in recent years. However, exploring the full potential of this approach requires fine tuned optimization and characterization approaches. Therefore, this study was conducted to achieve the following two goals. First, formulation and optimization of bovine serum albumin (BSA) load and release behavior as a function of cholesterol (CH) to sorbitan monostearate (Span 60) molar ratio. Second, investigating a cost- and time-effective polypeptide detecting method via methyl orange (MO) dye. To this aim, BSA-loaded niosomes were prepared by reversed-phase evaporation technique. The effect of CH to Sorbitan monostearate (Span 60) molar ratio on noisome entrapment efficiency (EE%) and release profile of BSA was studied using a ultraviolet (UV) spectrophotometer technique (NanoDrop 2000/2000c).Niosome with a 60% CH content showed the highest BSA EE% and release behavior. Then, BSA was dyed using MO in an acidic solution and used in BSA-niosome formulation. The MO-colored protein, loaded into the vesicles, was successfully assessed by an inverted light microscope, in order to observe the protein location in the vesicle. The results obtained in this study can be useful for various applications in different fields, including pharmaceutical, cosmetics, and drug delivery in biomedical and tissue engineering.

A novel electrochemical nanobiosensor for the ultrasensitive and specific detection of femtomolar-level gastric cancer biomarker miRNA-106a

Gastric cancer (GC) is the second leading cause of cancer-related deaths all over the world. miR-106a is a circulatory oncogenic microRNA (miRNA), which overexpresses in various malignancies, especially in GC. In this study, an ultrasensitive electrochemical nanobiosensor was developed for the detection of miR-106a using a double-specific probe methodology and a gold-magnetic nanocomposite as tracing tag. The successful modification of the electrode and hybridization with the target miRNA were confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. Differential pulse voltammetry (DPV) was used for quantitative evaluation of miR-106a via recording the reduction peak current of gold nanoparticles. The electrochemical signal had a linear relationship with the concentration of the target miRNA ranging from 1 × 10^-3 pM to 1 × 10³ pM, and the detection limit was 3 × 10^-4 pM. The proposed miRNA-nanobiosensor showed remarkable selectivity, high specificity, agreeable storage stability, and great performance in real sample investigation with no pretreatment or amplification. Consequently, our biosensing strategy offers such a promising application to be used for clinical early detection of GC and additionally the screen of any miRNA sequence.

99m Tc-anti-epidermal growth factor receptor nanobody for tumor imaging

Nanobodies are important biomolecules for tumor targeting. In this study, we synthesized and labeled anti-epidermal growth factor receptor (EGFR) nanobody OA-cb6 with ^99m Tc(CO)₃⁺ and evaluated its characteristics for targeting the EGFR in the A431 human epidermal carcinoma cell line. Nanobody radiolabeling was achieved with high yield and radiochemical purity, and the radioconjugate was stable. Biodistribution results in nude mice exhibited a favorable tumor-to-muscle ratio at 4-hr postinjection, and tumor location was visualized at 4 hr after injection of radiolabeled nanobody. Our result showed that the OA-cb6-^99m Tc-tricarbonyl radiolabeled nanobody is a promising radiolabeled biomolecule for tumor imaging in cancers with high EGFR overexpression.

Signal amplification strategy using gold/N-trimethyl chitosan/iron oxide magnetic composite nanoparticles as a tracer tag for high-sensitive electrochemical detection

This study presents a novel signal amplification method for high-sensitive electrochemical immunosensing. Gold (Au)/N-trimethyl chitosan (TMC)/iron oxide (Fe3O4) (shell/shell/core) nanocomposite was used as a tracing tag to label antibody. The tag was shown to be capable of amplifying the recognition signal by high-density assembly of Au nanoparticles (NPs) on TMC/Fe3O4 particles. The remarkable conductivity of AuNPs provides a feasible pathway for electron transfer. The method was found to be simple, reliable and capable of high-sensitive detection of human serum albumin as a model, down to 0.2 pg/ml in the range of 0.25-1000 pg/ml. Findings of the present study would create new opportunities for sensitive and rapid detection of various analytes.

Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe3O4 nanocomposites as a promising, nontoxic system for biomedical applications

The unique properties and applications of iron oxide and Au nanoparticles have motivated researchers to synthesize and optimize a combined nanocomposite containing both. By using various polymers such as chitosan, some of the problems of classic core-shell structures (such as reduced saturation magnetization and thick coating) have been overcome. In the present study, chitosan and one of its well-known derivatives, N-trimethylchitosan (TMC), were applied to construct three-layer nanocomposites in an Au/polymer/Fe3O4 system. It was demonstrated that replacement of chitosan with TMC reasonably improved the properties of the final nanocomposites including their size, magnetic behavior and thermal stability. Moreover, the results of the MTT assay showed no significant cytotoxicity effect when the Au/TMC/Fe3O4 nanocomposites were applied in vitro. These TMC-containing magnetic nanoparticles are well-coated by Au nanoparticles and have good biocompatibility and can thus play the role of a platform or a label in various fields of application, especially the biomedical sciences and biosensors.

Advances in phage display technology for drug discovery

INTRODUCTION

Over the past decade, several library-based methods have been developed to discover ligands with strong binding affinities for their targets. These methods mimic the natural evolution for screening and identifying ligand-target interactions with specific functional properties. Phage display technology is a well-established method that has been applied to many technological challenges including novel drug discovery.

AREAS COVERED

This review describes the recent advances in the use of phage display technology for discovering novel bioactive compounds. Furthermore, it discusses the application of this technology to produce proteins and peptides as well as minimize the use of antibodies, such as antigen-binding fragment, single-chain fragment variable or single-domain antibody fragments like VHHs.

EXPERT OPINION

Advances in screening, manufacturing and humanization technologies demonstrate that phage display derived products can play a significant role in the diagnosis and treatment of disease. The effects of this technology are inevitable in the development pipeline for bringing therapeutics into the market, and this number is expected to rise significantly in the future as new advances continue to take place in display methods. Furthermore, a widespread application of this methodology is predicted in different medical technological areas, including biosensing, monitoring, molecular imaging, gene therapy, vaccine development and nanotechnology.

Development of a new immunochromatographic assay using gold nanoparticles for screening of IgA deficiency

A new competitive immunochromatography (ICG) strip test based on polyclonal antibody (pAb) conjugated with gold nanoparticles (NPs) was developed and its applications for primary screening of immunoglobulin (Ig) A in serum were evaluated. Nanocolloidal gold as the detection reagent, with an average particle diameter of 20 nm, was synthesized and labelled pAb. The antibody-nanocolloidal gold probe was applied on the conjugate pad, and human IgA was immobilized on a nitrocellulose membrane as the capture reagent to prepare the ICG strip test. It took only 10 minutes to accomplish a semi-quantitative detection of serum IgA in this assay. In the optimized investigational conditions, the ICG strip test could distinguish human serum IgA in the range from 1 to 270 ng/mL with a detection limit of 5 ng/mL. The reliability of testing procedures was examined by performing the ICG strip test with 11 serum samples and comparing the results with those obtained via enzyme-linked immunosorbent assay (ELISA). The ICG strip was sufficiently sensitive and accurate for a rapid screening of IgA in human serum.

Effect of endurance training on retinol-binding protein 4 gene expression and its protein level in adipose tissue and the liver in diabetic rats induced by a high-fat diet and streptozotocin

AIMS/INTRODUCTION

The present study was designed to investigate from which tissues the decrease in retinol-binding protein 4 (RBP4) expression could contribute to the improvement of serum RBP4 and insulin resistance (IR) after endurance training.

MATERIALS AND METHODS

Male 7-week-old Wistar rats were randomly assigned into four groups including control (C), trained (T), diabetic control (DC) and trained diabetic (TD). At 8 weeks-of-age, diabetes was induced by a high-fat diet and intraperitoneal injection of low-dose streptozotocin (STZ; 35 mg/kg). Rats in the T and TD groups carried out a 7-week exercise program on a motorized treadmill (15-20 m/min for 20 min/day for 5 weeks), whereas the C and DC remained sedentary in their cages. Tissues gene expression and protein levels of RBP4 were assessed by using real-time polymerase chain reaction and western blot, respectively, while serum RBP4 was measured using an enzyme-linked immunosorbent assay kit.

RESULTS

Exercise significantly improved IR and reduced serum concentration of RBP4 in the TD group. This reduction of serum RBP4 was accompanied by decreased RBP4 protein expression in visceral fat tissue. In contrast, exercise had no significant effect on RBP4 expression in liver and subcutaneous fat tissue in the TD group. Exercise also significantly decreased RBP4 gene expression in visceral fat tissue and muscle, whereas the effect of exercise on liver RBP4 messenger ribonucleic acid expression was not significant.

CONCLUSIONS

The present study showed that the mechanism for RBP4 reducing the effect of endurance training could involve decreased RBP4 messenger ribonucleic acid expression and its protein level in adipose tissue in STZ-induced diabetic rats.

Association of urinary bisphenol a concentration with type-2 diabetes mellitus

BACKGROUND

Bisphenol A as an endocrine-disrupting chemical is widely used chemical in the manufacture of polycarbonate plastics and epoxy resin and has become ubiquitous environmental contaminants. Human exposure to Bisphenol A is widespread and recent studies have been shown to be associated with a higher risk for self-reported adverse health outcomes that may lead to insulin resistance and the development of type-2 diabetes mellitus. In this context, we sought to confirm the association between Bisphenol A and diabetes in a community-based analysis of Bisphenol A urinary concentrations investigation in adult population of Iran.

METHODS

Regression models were adjusted for age, sex, Body Mass Index, serum triglyceride level and serum cholesterol level and serum creatinine concentration. Main outcomes were reported diagnoses of diabetes that defined according the latest American Diabetes Association guidelines.

RESULTS

The median age of the 239 participants was 51.65 years and 119 people had type-2 diabetes mellitus. Urinary Bisphenol A was categorized into two groups based on the median for Bisphenol A (≤0. 85 to >0.85 μg/L). The results of statistical analysis revealed a clear association between hypertension, and type 2 diabetes (P < 0.05). The multi variable-adjusted odds ratio for type-2 diabetes mellitus associated with the group 1 (referent), of urinary Bisphenol A was 57.6 (95% confidence interval: 21.10-157.05; P-value < 0.001). A positive correlation between HbA1c and urinary BPA concentration was observed (r = 0.63, P = 0.001).

CONCLUSIONS

Urinary Bisphenol A levels are found to be associated with diabetes independent of traditional diabetes risk factors. Higher Bisphenol A exposure, reflected in higher urinary concentrations of Bisphenol A, is consistently associated with diabetes in the general adult population of the Iran. Studies to clarify the mechanisms of these associations are urgently needed.

Development of 3-hydroxybutyrate dehydrogenase enzyme biosensor based on carbon nanotube-modified screen-printed electrode

Precise detection of 3-hydroxybutyrate (HB) in biological samples is of great importance for management of diabetic patients. In this study, an HB biosensor based on single-walled carbon nanotubes (SWCNTs)-modified screen-printed electrode (SPE) was developed to determine the concentration of HB in serum. The specific detecting enzyme, HB dehydrogenase, was physically immobilised on SWCNTs deposited on the surface of SPEs. The electrochemical measurement of HB that involved cyclic voltammetry was based on the sAgnal produced by j3-nicotinamide adenine dinucleotide (NADH), one of the products of the enzymatic reaction. The application of SWCNT reduced the oxidation potential of NADH to about -0.05 V. Electrochemical measurements showed that the response of this biosensor had relevant good linearity in the range of 0.1-2 mM with a low detection limit of 0.009 mM. Investigation of biosensor response in the presence of interfering molecules verified its specificity. Furthermore, the study of long-term stability demonstrated the acceptable efficiency of this biosensor for about 100 days.

Development of a nanogold-based immunochromatographic assay for detection of morphine in urine using the Amor-HK16 monoclonal antibody

A simple, rapid competitive immunochromatography (ICG) strip test was developed to detect morphine in urine samples using a monoclonal antibody produced in-house and conjugated to gold nanoparticles. Hybridoma cells were cultured and the Amor-HK16 monoclonal antibody against morphine was obtained from the supernatant after purification by salting out and passing through a Protein G-Agarose affinity column. Morphine was obtained from morphine sulfate and a C6-hemisuccinate derivative of morphine was prepared, conjugated to bovine serum albumin, and immobilized to a nitrocellulose membrane as the test line. Goat anti-mouse antibody was used as a binder in the control line in the detection zone of the strip. Colloidal gold particles of diameter approximately 20 nm were prepared and conjugated to the monoclonal antibody. The detection limit of the test strip was found to be 2000 ng/mL of morphine in urine samples. Reliability was determined by performing the ICG test on 103 urine samples and comparing the results with those obtained by thin-layer chromatography. The sensitivity of the test was 100%, and the analysis time for the assay was approximately 5 min. The new ICG method was adequately sensitive and accurate for the rapid screening of morphine in urine.

An electrochemical biosensor for 3-hydroxybutyrate detection based on screen-printed electrode modified by coenzyme functionalized carbon nanotubes

3-Hydroxybutyrate, one of the main blood ketone bodies, has been considered as a critical indicator for diagnosis of diabetic ketoacidosis. Biosensors designed for detection of 3-hydroxybutyrate with advantages of precision, easiness and speedy performance have attracted increasing attention. This study attempted to develop a 3-hydroxybutyrate dehydrogenase-based biosensor in which single-walled carbon nanotubes (SWCNT) was used in order to immobilize the cofactor, NAD(+), on the surface of screen-printed electrode. The formation of NAD(+)-SWCNT conjugates was assessed by electrochemistry and electron microscopy. Cyclic voltammetry was used to analyze the performance of this biosensor electrochemically. The considerable shelf life and reliability of the proposed biosensor to analyze real sample was confirmed by this method. The reduction in the over potential of electrochemical oxidation of NADH to -0.15 V can be mentioned as a prominent feature of this biosensor. This biosensor can detect 3-hydroxybutyrate in the linear range of 0.01-0.1 mM with the low detection limit of 0.009 mM. Simultaneous application of screen-printed electrode and SWCNT has made the biosensor distinguished which can open new prospects for detection of other clinically significant metabolites.

The association of carotid intima media thickness with retinol binding protein-4 and total and high molecular weight adiponectin in type 2 diabetic patients

BACKGROUND

The aim of this study was to investigate whether carotid intima media thickness (CIMT) is associated with serum level of retinol- binding protein-4 (RBP4) and total and high molecular weight (HMW) adiponectin in type 2 diabetes (T2DM) without clinical symptom of atherosclerotic disease.

METHOD

101 type 2 diabetic patients (mean age, 53.63 ± 8.42 years) and 42 body mass index (BMI) matched control (mean age 50.1 ± 8.4) were recruited. The CIMT was assessed by using B-mode ultrasonography, while serum levels of RBP4 and total and HMW adiponectin were measured by using enzyme linked immunosorbant assay (ELISA). Linear regression analysis was performed with CIMT as dependent variable and adipokines and cardio metabolic risk factors as independent variables.

RESULT

The CIMT was higher in diabetic group compared to control group (p <0.05). The mean concentration of RBP4 and total and HMW adiponectin did not differ between two groups.Age (B = 0.44 P <0.05), blood pressure (B = 0.37 P = <0.05), waist circumference (B = -0.21 P <0.05) and TG (B = 0.1 P <0.05) were identified as independent predictors for CIMT in diabetic group, while RBP4 and adiponectin were not associated with CIMT neither in diabetic group nor in control group.

CONCLUSION

In conclusion, the present study showed that serum levels of RBP4 or total and HMW adiponectin were not potential predictors of CIMT in type 2 diabetic patients who exposed to this risk factor at least for nine years.