Ferrocene-graphene sheets for high-efficiency quenching of electrochemiluminescence from Au nanoparticles functionalized cadmium sulfide flower-like three dimensional assemblies and sensitive detection of prostate specific antigen

Silica Nanochannels as Nanoreactors for the Confined Synthesis of Ag NPs to Boost Electrochemical Stripping Chemiluminescence of the Luminol-O2 System for the Sensitive Aptasensor

Herein, we, for the first time, synthesize silver nanoparticles (Ag NPs) within the nanochannels of amino group-functionalized vertically ordered mesoporous silica films (NH2-VMSF) and investigate their coreaction accelerator role in the luminol-dissolved oxygen (O2) electrochemical stripping chemiluminescence (ESCL) system. The synthesized Ag NPs are capable of electrocatalytic reduction of O2 to superoxide radicals, and meanwhile, sliver ions (Ag+) electrochemically stripped from Ag NPs can promote the amount of luminol anion radicals, generating the boosted ECL intensity of the luminol-dissolved O2 system. This proposed Ag NPs@NH2-VMSF on the indium tin oxide electrode was applied to construct the ESCL aptasensor for quantitative determination of prostate-specific antigen (PSA), yielding a low detection limit [0.19 pg/mL (S/N = 3)] and a broad linear dynamic range (1 pg/mL to 100 ng/mL). Furthermore, good analytical performance of PSA in serum with satisfactory recoveries and low relative standard deviation values is achieved by our developed ESCL aptasensor, rendering it a convenient and sensitive method for PSA determination in clinical applications and further broadening the strategy of ESCL techniques.

Properties and Applications of Graphene and Its Derivatives in Biosensors for Cancer Detection: A Comprehensive Review

Cancer is one of the deadliest diseases worldwide, and there is a critical need for diagnostic platforms for applications in early cancer detection. The diagnosis of cancer can be made by identifying abnormal cell characteristics such as functional changes, a number of vital proteins in the body, abnormal genetic mutations and structural changes, and so on. Identifying biomarker candidates such as DNA, RNA, mRNA, aptamers, metabolomic biomolecules, enzymes, and proteins is one of the most important challenges. In order to eliminate such challenges, emerging biomarkers can be identified by designing a suitable biosensor. One of the most powerful technologies in development is biosensor technology based on nanostructures. Recently, graphene and its derivatives have been used for diverse diagnostic and therapeutic approaches. Graphene-based biosensors have exhibited significant performance with excellent sensitivity, selectivity, stability, and a wide detection range. In this review, the principle of technology, advances, and challenges in graphene-based biosensors such as field-effect transistors (FET), fluorescence sensors, SPR biosensors, and electrochemical biosensors to detect different cancer cells is systematically discussed. Additionally, we provide an outlook on the properties, applications, and challenges of graphene and its derivatives, such as Graphene Oxide (GO), Reduced Graphene Oxide (RGO), and Graphene Quantum Dots (GQDs), in early cancer detection by nanobiosensors.

Ultrasensitive Immunosensor for Prostate-Specific Antigen Based on Enhanced Electrochemiluminescence by Vertically Ordered Mesoporous Silica-Nanochannel Film

Ultrasensitive and specific detection of prostate-specific antigen (PSA) in complex biological samples is crucial for early diagnosis and treatment of prostate-related diseases. Immunoassay with a simple sensing interface and ultrahigh sensitivity is highly desirable. Herein, a novel electroluminescence (ECL) immunosensing platform is demonstrated based on the equipment of vertically ordered mesoporous silica-nanochannel films (VMSFs) with PSA antibody, which is able to realize ultrasensitive detection of PSA in human serum. Through the electrochemically assisted self-assembly (EASA) method, the VMSF is easily grown on an indium tin oxide (ITO) electrode in a few seconds. Owing to a large surface area and the negatively charged surface, VMSF nanochannels display strong electrostatic attraction to the positively charged ECL luminophores (tris(2,2-bipyridyl) dichlororuthenium (II), (Ru(bpy)₃²⁺), leading to two orders-of-magnitude enhancement of ECL emission compared with that of the bare ITO electrode. The outer surface of the VMSF is functionalized with reactive epoxy groups, which further allows covalent attachment of PSA antibody (Ab) on the entry of nanochannels. As the combination of PSA with Ab decreases the ECL signal by hindering the mass transfer of ECL luminophores and coreactant, the developed immunosensor can achieve ultrasensitive detection of PSA ranging from 1 pg ml⁻¹ to 100 ng ml⁻¹ with a limit of detection (LOD) of 0.1 pg ml⁻¹. Considering the antifouling ability of the VMSF, sensitive detection of PSA in human serum is also realized. The proposed nanochannel-based immunosensor may open up a new way for the facile development of the universal immunosensing platform for rapid and ultrasensitive detection of disease markers.

Nanotechnology-based approaches for effective detection of tumor markers: A comprehensive state-of-the-art review

As well-appreciated biomarkers, tumor markers have been spotlighted as reliable tools for predicting the behavior of different tumors and helping clinicians ascertain the type of molecular mechanism of tumorigenesis. The sensitivity and specificity of these markers have made them an object of even broader interest for sensitive detection and staging of various cancers. Enzyme-linked immunosorbent assay (ELISA), fluorescence-based, mass-based, and electrochemical-based detections are current techniques for sensing tumor markers. Although some of these techniques provide good selectivity, certain obstacles, including a low sample concentration or difficulty carrying out the measurement, limit their application. With the advent of nanotechnology, many studies have been carried out to synthesize and employ nanomaterials (NMs) in sensing techniques to determine these tumor markers at low concentrations. The fabrication, sensitivity, design, and multiplexing of sensing techniques have been uplifted due to the attractive features of NMs. Various NMs, such as magnetic and metal nanoparticles, up-conversion NPs, carbon nanotubes (CNTs), carbon-based NMs, quantum dots (QDs), and graphene-based nanosensors, hyperbranched polymers, optical nanosensors, piezoelectric biosensors, paper-based biosensors, microfluidic-based lab-on-chip sensors, and hybrid NMs have proven effective in detecting tumor markers with great sensitivity and selectivity. This review summarizes various categories of NMs for detecting these valuable markers, such as prostate-specific antigen (PSA), human carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), human epidermal growth factor receptor-2 (HER2), cancer antigen 125 (CA125), cancer antigen 15-3 (CA15-3, MUC1), and cancer antigen 19-9 (CA19-9), and highlights recent nanotechnology-based advancements in detection of these prognostic biomarkers.

Electrochemiluminescent determination of prostate-specific antigen using Au@(MoS2/GO/o-MWNTs) nanohybrids as co-reaction accelerator and hyperbranched hybridization chain reaction for signal amplification

Three-dimensional flowerlike Au@(MoS₂/GO/o-MWNTs) nanohybrids (abbreviated as AMGMs) were synthesized and then introduced into an electrochemiluminescence (ECL) system as a new co-reaction accelerator for the ultrasensitive prostate-specific antigen (PSA). The AMGMs not only served as a substrate with good conductivity and a large specific surface area for loading abundant primary antibodies but also acted as an effective co-reaction accelerator; the co-reaction accelerator could interact with a co-reactant rather than the luminophore to boost the generation of free radical intermediates, thereby producing abundant excited states of luminophores to amplify the ECL signal response. Additionally, an anticipated signal amplification strategy based on the hybridization chain reaction (HCR) was developed by gathering a large amount of a DNA initiator on gold nanoparticles. These gathered DNA initiators could generate multiple DNA concatemers and attach more signal molecules, which resulted in outstanding exponential signal amplification. Consequently, the ECL immunosensor demonstrated high sensitivity, with a linear range from 0.1 pg mL^-1 to 50 ng mL^-1 and a detection limit of 0.028 pg mL^-1. In addition, the immunosensor displayed excellent stability and selectivity. It was evaluated by analyzing human serum sample. The recovery obtained was 98.80-112.00% and the RSD was 1.73-3.12%, indicating the immunosensor could be applied to the simultaneous detection of PSA in human serum samples. Graphical abstract.

A novel molecularly imprinted electrochemiluminescence sensor based on cobalt nitride nanoarray electrode for the sensitive detection of bisphenol S

A substitute for bisphenol A (BPA), bisphenol S (BPS) has endocrine disruptive and toxic effects and could pose potential risk on human health and the environment. Herein, we fabricated a sensitive molecularly imprinted electrochemiluminescence (MIECL) sensor for the determination of BPS. CoN nanoarray with outstanding electrical conductivity was prepared and it directly served as the sensor platform. Especially, due to the high surface area of the porous CoN nanoarray, the ECL probe of Ru(bpy)3 2+ could be absorbed on the electrode. By means of the cation exchange of Nafion membrane and utilizing tripropylamine (TPrA) as co-reactant, boosted ECL signals were obtained. Meanwhile, by combining with molecularly imprinted polymers (MIPs), the constructed sensor achieved specific recognition of BPS. On the basis of the superior properties of the CoN nanoarray-based electrode, the ECL signal of the proposed sensor was linearly proportional to the BPS concentration from 2.4 × 10-9 to 5.0 × 10-5 mol L-1 (R 2 = 0.9965) with a low limit of detection (LOD) of 8.1 × 10-10 mol L-1 (S/N = 3). To test the accuracy of the proposed method, the HPLC method was adopted to analyze drinking water samples as a comparison. The t-test result proved that discrepancies between HPLC analysis and the method using the fabricated MIECL sensor were acceptable. The developed MIECL sensor with the sensitive, selective, reproducible, and stable analytical performance provides a potential pathway for the detection of BPS and other BPA substitutes in drinking water samples.

Highly sensitive bioaffinity electrochemiluminescence sensors: Recent advances and future directions

Electrogenerated chemiluminescence (also called electrochemiluminescence and abbreviated ECL) has attracted much attention in various fields of analysis due to the potential remarkably high sensitivity, extremely wide dynamic range and excellent controllability. Electrochemiluminescence biosensor, by taking the advantage of the selectivity of the biological recognition elements and the high sensitivity of ECL technique was applied as a powerful analytical device for ultrasensitive detection of biomolecule. In this review, we summarize the latest sensing applications of ECL bioanalysis in the field of bio affinity ECL sensors including aptasensors, immunoassays and DNA analysis, cytosensor, molecularly imprinted sensors, ECL resonance energy transfer and ratiometric biosensors and give future perspectives for new developments in ECL analytical technology. Furthermore, the results herein discussed would demonstrate that the use of nanomaterials with unique chemical and physical properties in the ECL biosensing systems is one of the most interesting research lines for the development of ultrasensitive electrochemiluminescence biosensors. In addition, ECL based sensing assays for clinical samples analysis and medical diagnostics and developing of immunosensors, aptasensors and cytosensor for this purpose is also highlighted.

Application of various optical and electrochemical aptasensors for detection of human prostate specific antigen: A review

Early stage detection of prostate cancer, one of the main causes of mortality among men, is of great importance for better treatment of the patients. Prostate specific antigen (PSA) is a glycoprotein which has been considered as the most potential serological biomarker for the detection of prostate cancer. Among the various techniques employed for PSA detection, aptamer-based biosensors (aptasensors) have achieved notable attention because of their unique features and great potentials as diagnostic tools. A variety of strategies such as integration of nanomaterials (NMs) into the structure of aptasensors have also been applied for enhancing the sensitivity of PSA detection. This article reviews recent advances in various optical and electrochemical aptasensors used for PSA detection.

Biomarkers-based Biosensing and Bioimaging with Graphene for Cancer Diagnosis

At the onset of cancer, specific biomarkers get elevated or modified in body fluids or tissues. Early diagnosis of these biomarkers can greatly improve the survival rate or facilitate effective treatment with different modalities. Potential nanomaterial-based biosensing and bioimaging are the main techniques in nanodiagnostics because of their ultra-high selectivity and sensitivity. Emerging graphene, including two dimensional (2D) graphene films, three dimensional (3D) graphene architectures and graphene hybrids (GHs) nanostructures, are attracting increasing interests in the field of biosensing and bioimaging. Due to their remarkable optical, electronic, and thermal properties; chemical and mechanical stability; large surface area; and good biocompatibility, graphene-based nanomaterials are applicable alternatives as versatile platforms to detect biomarkers at the early stage of cancer. Moreover, currently, extensive applications of graphene-based biosensing and bioimaging has resulted in promising prospects in cancer diagnosis. We also hope this review will provide critical insights to inspire more exciting researches to address the current remaining problems in this field.

Dual-responsive electrochemical immunosensor for detection of insulin based on dual-functional zinc silicate spheres-palladium nanoparticles

In this study, described an electrochemical immunoassay for insulin that is based on the use of zinc silicate spheres loaded with palladium nanoparticles (Zn₂SiO₄-PdNPs) that act as dual-function labels. The Zn₂SiO₄-PdNPs display high electrocatalytic activity towards the reduction of H₂O₂ and high sensitivity in chronoamperometry. The Zn₂SiO₄-PdNPs decrease the electron transfer rate between the electrolyte and the surface of the electrode, which can increase the changed current and enhance the sensitivity of the immunosensor as detected by square wave voltammetry (SWV). Electrodeposited gold is used as the matrix material. The icosahedral gold nanocrystals are coated with the primary antibodies formed a 3D mode to against abundant of insulin. Under optimal conditions, the assay has a linear response in the 0.1pgmL^-1 to 50ngmL^-1 insulin concentration range, and the limit of detection of the SWV and CA methods are 0.25 fg mL^-1 and 80 fg mL^-1, respectively. Moreover, the immunosensor holds an outstanding analytical performance for the insulin detection and has promising potential in clinical diagnosis.

3D Nanostructured Palladium-Functionalized Graphene-Aerogel-Supported Fe3O4 for Enhanced Ru(bpy)32+-Based Electrochemiluminescent Immunosensing of Prostate Specific Antigen

We developed a novel Ru(bpy)₃²⁺-based electrochemiluminescence (ECL) immunosensor utilizing palladium nanoparticle (Pd NP)-functionalized graphene-aerogel-supported Fe₃O₄ (FGA-Pd) for real-sample analysis of prostate specific antigen (PSA). 3D nanostructured FGA-Pd, as a novel ECL carrier, was prepared by in situ reduction. Large amounts of Ru(bpy)₃²⁺ could combine with FGA-Pd via electrostatic interaction to establish a brand-new ECL emitter (Ru@FGA-Pd) for improving ECL efficiency. The obtained Ru@FGA-Pd composite was utilized to label the secondary antibody, which generated strong ECL signals with tripropylamine (TPrA) as a coreactant. Furthermore, we demonstrated that the participation of Pd NPs endowed FGA with favorable electrocatalytic ability in the luminescence process to produce more excited state [Ru(bpy)₃²⁺]* for realizing desirable signal amplification. In addition, the primary antibody was captured by gold nanoparticle (Au NP)-functionalized Fe₂O₃ nanodendrites (Au-FONDs), which possessed good electrical conductivity and favorable biocompatibility. Under optimum conditions, the fabricated sandwich-type ECL immunosensor showed a sensitive response to PSA with a low detection limit of 0.056 pg/mL (S/N = 3) and a calibration range of 0.0001-50 ng/mL. Featuring favorable selectivity, stability, and repeatability, the proposed immunosensor is expected to blaze a novel trail for the real sample detection of PSA and other biomarkers.

Graphene oxide@gold nanorods-based multiple-assisted electrochemiluminescence signal amplification strategy for sensitive detection of prostate specific antigen

A novel and competitive electrochemiluminescence (ECL) aptasensor for prostate specific antigen (PSA) assay was constructed using gold nanorods functionalized graphene oxide (GO@AuNRs) multilabeled with glucose oxidase (GOD) and streptavidin (SA) toward luminol-based ECL system. A strong initial ECL signal was achieved by electrodeposited gold (DpAu) on the electrode because of gold nanoparticles (AuNPs) motivating the luminol ECL signal. The signal probes prepared by loading GOD and SA-biotin-DNA on GO@AuNRs were used for achieving multiple signal amplification. In the absence of PSA, the signal probes can be attached on the electrode by hybridization reaction between PSA aptamer and biotin-DNA. In this state, the GOD loaded on the probe could catalyze glucose to in situ produce H₂O₂ and then AuNRs catalyze H₂O₂ to generate abundant reactive oxygen species (ROSs) in luminol ECL reaction. Both the high-content GOD and AuNRs in the signal probe amplified the ECL signal in the ECL system. Moreover, the combination of SA with biotin-DNA further expands ECL intensity. The integration of such amplifying effects in this protocol endows the aptasensor with high sensitivity and good selectivity for PSA detection. This aptasensor exhibits a linear relation in the range of 0.5pgmL^-1 to 5.0ngmL^-1 with the detection limit of 0.17pgmL^-1 (S/N = 3). Besides, the strategy was successfully applied in determination of human serum samples with recovery of 81.4-116.0%.

Nanomaterial-based biosensors for detection of prostate specific antigen

Screening serum for the presence of prostate specific antigen (PSA) belongs to the most common approach for the detection of prostate cancer. This review (with 156 refs.) addresses recent developments in PSA detection based on the use of various kinds of nanomaterials. It starts with an introduction into the field, the significance of testing for PSA, and on current limitations. A first main section treats electrochemical biosensors for PSA, with subsections on methods based on the use of gold electrodes, graphene or graphene-oxide, carbon nanotubes, hybrid nanoparticles, and other types of nanoparticles. It also covers electrochemical methods based on the enzyme-like activity of PSA, on DNA-, aptamer- and biofuel cell-based methods, and on the detection of PSA via its glycan part. The next main section covers optical biosensors, with subsections on methods making use of surface plasmon resonance (SPR), localized SPR and plasmonic ELISA-like schemes. This is followed by subsections on methods based on the use of fiber optics, fluorescence, chemiluminescence, Raman scattering and SERS, electrochemiluminescence and cantilever-based methods. The most sensitive biosensors are the electrochemical ones, with lowest limits of detection (down to attomolar concentrations), followed by mass cantilever sensing and electrochemilumenescent strategies. Optical biosensors show lower performance, but are still more sensitive compared to standard ELISA. The most commonly applied nanomaterials are metal and carbon-based ones and their hybrid composites used for different amplification strategies. The most attractive sensing schemes are summarized in a Table. The review ends with a section on conclusions and perspectives.