Progress in cancer biomarkers monitoring strategies using graphene modified support materials

Au NPs modified Ni-B nanosheets/graphene oxide three-dimensional network as label-free electrochemical immunosensor for the detection of diethylstilbestrol

Three-dimensional (3D) network provide a promising platform for construction of high sensitive electrochemical immunosensor due to the benefits of high specific surface area and electron mobility. Herein, a sensitive label-free electrochemical immunosensor based on Au nanoparticles modified Ni-B nanosheets/graphene matrix was constructed to detect diethylstilbestrol (DES). The 3D network not only could increase the electron transport rate and surface area, but also could provide confinement area, which is conducive to increases the collision frequency with the active site. Moreover, Au NPs also have good biocompatibility, which is beneficial for ligating antibodies. Benefiting from the 3D network structure and Au collective effect, the electrochemical immunosensor possess sterling detection ability with wide linear response range (0.00038-150 ng/mL) and low detection limit (31.62 fg/mL). Moreover, the constructed immunosensor can also be extend to detect DES in Tap-water and river water. This work may provide a novel material model for the construction of high sensitive immunosensor.

Portable photoelectrochemical immunoassay with micro-electro-mechanical-system for alpha-fetoprotein in hepatocellular carcinoma

Early detection of cancer has a profound impact on patient survival and treatment outcomes considering high treatment success rates and reduced treatment complexity. Here, we developed a portable photoelectrochemical (PEC) immune platform for sensitive testing of alpha-fetoprotein (AFP) based on Pt nanocluster (Pt NCs) loaded defective-state g-C3N4 photon-electron transducers. The broad forbidden band structure of g-C3N4 was optimized by the nitrogen doping strategy and additional homogeneous porous structure was introduced to further enhance the photon utilization. In addition, the in-situ growth of Pt NCs provided efficient electron transfer catalytic sites for sacrificial agents, which were used to further improve the sensitivity of the sensor. Efficient photoelectric conversion under a hand-held flashlight was determined by the geometry of the transducer and the energy band design, and the portable design of the PEC sensor was realized. The developed sensing platform exhibited a wide linear response range (0.1-50 ng mL-1) and low limit of detection (0.043 ng mL-1) for AFP under optimum conditions. This work provides a new idea for designing portable PEC biosensing platforms to meet the current mainstream POC testing needs.

Multiplexed detection of biomarkers using a microfluidic chip integrated with mass-producible micropillar array electrodes

Quantifying multiple biomarkers with high sensitivity in tiny biological samples is essential to meet the growing demand for point-of-care testing. This paper reports the development of a novel microfluidic device integrated with mass-producible micropillar array electrodes (μAEs) for multiple biomarker detections. The μAE are mass-fabricated by soft lithography and hot embossing technique. Pt-Pd bimetallic nanoclusters (BNC) are modified on the surface of μAEs by constant potential (CP)/multi-potential step (MPS) electrodeposition strategies to improve the electroanalytical performance. The experimental result displays that Pt-Pd BNC/μAEs have good sensitivity enhancement compared with bare planar electrodes and bare μAEs, the enhancement being 56.5 and 9.5 times respectively, from the results of the H₂O₂ detection. Furthermore, glucose, uric acid and sarcosine were used as model biomarkers to show the biosensing capability with high sensitivity. The linear range and LOD of the glucose, uric acid and sarcosine detection are 0.1 mM-12 mM, 10 μM-800 μM and 2.5 μM-100 μM, 58.5, 3.4 and 0.4 μM, respectively. In particular, biosensing chips show wide linear ranges covering required detection ranges of glucose, uric acid and sarcosine in human serum, indicating the developed device has great potential in self-health management and clinical requirements.

An electrochemical immunosensor for an alpha-fetoprotein cancer biomarker on a carbon black/palladium hybrid nanoparticles platform

The early detection of cancer is a key step in cancer survival. Thus, there is a need to develop low-cost technologies, such as electrochemical immunosensor technologies, for timely screening and diagnostics. The discovery of alpha-feto protein (AFP) as a tumour-associated antigen lends AFP as a biomarker for cancer detection and monitoring. Thus, immunosensors can be developed to target AFP in cancer diagnostics. Hence, we report the application of a hybrid nanocomposite of carbon black nanoparticles (CBNPs) and palladium nanoparticles (PdNPs) as a platform for the electrochemical immunosensing of cancer biomarkers. The hybrid carbon-metal nanomaterials were immobilised by using the drop-drying and electrodeposition technique on a glassy carbon electrode, followed by the immobilisation of the anti-AFP to fabricate an immunosensor. The nanoparticles were characterised with electron microscopy, voltammetry, and electrochemical impedance spectroscopy (EIS). Square wave voltammetry (SWV) and EIS were used to study the immunosensor signal toward the bio-recognition of the AFP cancer biomarker. The hybrid nanoparticles enhanced the immunosensor performance. A linear detection range from 0.005 to 1000 ng mL^-1 with low detection limits of 0.0039 ng mL^-1 and 0.0131 ng mL^-1 were calculated for SWV and EIS, respectively. The immunosensor demonstrated good stability, reproducibility, and selectivity. Its real-life application potential was tested with detection in human serum matrix.

Bio-inspired nanozyme with ultra-thin Fe-Bi2O2S nanosheets for in-situ amplified photoelectrochemical immunoassay of cancer-related protein

A Fe-loaded Bi₂O₂S nanosheet photoanode serving as photoelectric biomonitoring platform for the detection of prostate-specific antigen (PSA) using biologically inspired prussian nanoparticle (PB)-catalyzed biocatalytic precipitation strategy was developed. Primarily, the signal probe PB-mAb₂ obtained by electrostatic adsorption was immobilized on a microplate in the presence of target PSA, and 4-chloro-1-naphthol (4-CN) was oxidized to benzo-4-chloro-hexadienone (4-CD) with the assistance of exogenous hydrogen peroxide, which was generated by a large number of hydroxyl radicals catalyzed by PB. The generated 4-CD showed strongly low conductivity characteristics to burst the photocurrent of highly photoactive Fe-Bi₂O₂S photoanode. The split incubation reaction could be suitable for high volume and low-cost rapid detection. A dynamic response range of 0.1-100 ng mL^-1 with a limit of detection of 34.2 pg mL^-1 was achieved with the sensor based on a photoelectric sensing platform and a biomimetic catalytic precipitation reaction. Equally important, the sensor also showed good potential in the detection of real samples compared to commercially available ELISA kits. In conclusion, this work provides a fresh scheme for the development of sensitive biosensors through a bio-inspired catalytic strategy of versatility and a photoanode coupling with high photoelectric activity.

A simple, sensitive, label-free electrochemical immunosensor based on the chitosan-coated silver/cerium oxide (CS@Ag/CeO2) nanocomposites for the detection of alpha-fetoprotein (AFP)

Metal oxide-based sensors have the benefit of inexpensive, quick response, and high sensitivity in detecting specific biological species. In this article, a simple electrochemical immunosensor was fabricated using antibody-chitosan coated silver/cerium oxide (Ab-CS@Ag/CeO₂) nanocomposites on a gold electrode for sensitive alpha-fetoprotein (AFP) diagnosis in human serum samples. Successfully synthesis of AFP antibody-CS@Ag/CeO₂conjugates was confirmed through Fourier transform infrared spectra of the prototype. The amine coupling bond chemistry was then used to immobilize the resultant conjugate on a gold electrode surface. It was observed that the interaction of the synthesized Ab-CS@Ag/CeO₂nanocomposites with AFP prevented an electron transfer and reduced the voltammetric Fe(CN)₆^3-/4-peak current, which was proportional to the amount of AFP. The linear ranges of AFP concentration were found from 10^-12-10^-6g.ml^-1. The limit of detection was calculated using the calibration curve and came out to be 0.57 pg.ml^-1. The designed label-free immunosensor successfully detected AFP in human serum samples. As a result, the resulting immunosensor is a promising sensor plate form for AFP detection and could be used in clinical bioanalysis.

Paper-based photoelectrochemical immunoassay for ultrasensitive screening of carcinoembryonic antigen on hollow CdS/CdMoO4-functionalized photoanode

Lab-based testing systems utilizing photoelectrochemical (PEC) biosensing methodologies for the ultrasensitive carcinoembryonic antigen (CEA) have been developed, although the majority have shown complicated operating procedures and dependence on precise apparatus. Herein, a portable photoelectrochemical split diagnostic platform based on a hollow CdS/CdMoO₄ (h-CdS@CdMoO₄) shell-shell structured photoanode system was developed for ultrasensitive detection of CEA. Using a small LED flashlight as the excitation light source and a digital multimeter (DMM) as the signal readout device, real-time CEA on a paper-based printed screen electrode developed in-house was quickly detected. The composite h-CdS@CdMoO₄ featured a special hollow shell-shell heterojunction structure that optimizes photon usage in the bulk phase on the one hand, and facilitates directed separation of the electrons and holes therein on the other. A split-sandwich immunoassay and detection antibodies for modified glucose oxidase were introduced into the paper-based photoanode test system, and the signals were displayed with a DMM to realize a point-of-care test for CEA. Under optimized conditions, the constructed portable PEC sensing system was sensitive to the target CEA from 0.02 to 50.0 ng mL^-1 with a detection limit of 11.3 pg mL^-1. Interferent experiments and stability test evaluations demonstrate the specificity and robustness of the constructed paper-based portable PEC sensor. The portable, paper-based PEC immunoassay system developed offers a fresh way of exploring affordable, approachable sensors to satisfy both the relevant community medical testing demands and hospital objectives for quick testing.

Effect of contact resistance on the electrical conductivity of polymer graphene nanocomposites to optimize the biosensors detecting breast cancer cells

This study focuses on the contact regions among neighboring nanoparticles in polymer graphene nanocomposites by the extension of nanosheets. The resistance of graphene and the contact zones represent the total resistance of the prolonged nanosheets. Furthermore, the graphene size, interphase depth, and tunneling distance express the effective volume portion of graphene, while the onset of percolation affects the fraction of percolated nanosheets. Finally, a model is developed to investigate the conductivity of the samples using the graphene size, interphase depth, and tunneling size. In addition to the roles played by certain factors in conductivity, the experimental conductivity data for several samples confirm the conductivity predictions. Generally, the polymer sheet in tunnels determines the total resistance of the extended nanosheets because graphene ordinarily exhibits negligible resistance. In addition, a large tunnel positively accelerates the onset of percolation, but increases the tunneling resistance and attenuates the conductivity of the nanocomposite. Further, a thicker interphase and lower percolation threshold promote the conductivity of the system. The developed model can be applied to optimize the biosensors detecting the breast cancer cells.

Graphene Biodevices for Early Disease Diagnosis Based on Biomarker Detection

The early diagnosis of diseases plays a vital role in healthcare and the extension of human life. Graphene-based biosensors have boosted the early diagnosis of diseases by detecting and monitoring related biomarkers, providing a better understanding of various physiological and pathological processes. They have generated tremendous interest, made significant advances, and offered promising application prospects. In this paper, we discuss the background of graphene and biosensors, including the properties and functionalization of graphene and biosensors. Second, the significant technologies adopted by biosensors are discussed, such as field-effect transistors and electrochemical and optical methods. Subsequently, we highlight biosensors for detecting various biomarkers, including ions, small molecules, macromolecules, viruses, bacteria, and living human cells. Finally, the opportunities and challenges of graphene-based biosensors and related broad research interests are discussed.

Synthesis, characterisation and cytotoxicity of gold microwires for ultra-sensitive biosensor development

With the long-term goal of developing an ultra-sensitive microcantilever-based biosensor for versatile biomarker detection, new controlled bioreceptor-analytes systems are being explored to overcome the disadvantages of conventional ones. Gold (Au) microwires have been used as a probe to overcome the tolerance problem that occurs in response to changes in environmental conditions. However, the cytotoxicity of Au microwires is still unclear. Here, we examined the cytotoxicity of Au microwires systems using both commercial and as-synthesised Au microwires. In vitro experiments show that commercial Au microwires with an average quoted length of 5.6 µm are highly toxic against Gram-negative Escherichia coli (E. coli) at 50 µg/mL. However, this toxicity is due to the presence of CTAB surfactant not by the microwires. Conversely, the as-synthesised Au microwires show non-cytotoxicity even at the maximum viable concentration (330 µg/mL). These findings may lead to the development of potentially life-saving cytotoxicity-free biosensors for an early diagnostic of potential diseases.

Detection Technologies for Reactive Oxygen Species: Fluorescence and Electrochemical Methods and Their Applications

Reactive oxygen species (ROS) have been found in plants, mammals, and natural environmental processes. The presence of ROS in mammals has been linked to the development of severe diseases, such as diabetes, cancer, tumors, and several neurodegenerative conditions. The most common ROS involved in human health are superoxide (O2•-), hydrogen peroxide (H2O2), and hydroxyl radicals (•OH). Organic and inorganic molecules have been integrated with various methods to detect and monitor ROS for understanding the effect of their presence and concentration on diseases caused by oxidative stress. Among several techniques, fluorescence and electrochemical methods have been recently developed and employed for the detection of ROS. This literature review intends to critically discuss the development of these techniques to date, as well as their application for in vitro and in vivo ROS detection regarding free-radical-related diseases. Moreover, important insights into and further steps for using fluorescence and electrochemical methods in the detection of ROS are presented.

Sublethal exposure of small few-layer graphene promotes metabolic alterations in human skin cells

Small few-layer graphene (sFLG), a novel small-sized graphene-related material (GRM), can be considered as an intermediate degradation product of graphene. GRMs have a promising present and future in the field of biomedicine. However, safety issues must be carefully addressed to facilitate their implementation. In the work described here, the effect of sub-lethal doses of sFLG on the biology of human HaCaT keratinocytes was examined. A one-week treatment of HaCaTs with sub-lethal doses of sFLG resulted in metabolome remodeling, dampening of the mitochondrial function and a shift in the redox state to pro-oxidant conditions. sFLG raises reactive oxygen species and calcium from 24 h to one week after the treatment and this involves the activation of NADPH oxidase 1. Likewise, sFLG seems to induce a shift from oxidative phosphorylation to glycolysis and promotes the use of glutamine as an alternative source of energy. When sub-toxic sFLG exposure was sustained for 30 days, an increase in cell proliferation and mitochondrial damage were observed. Further research is required to unveil the safety of GRMs and degradation-derived products before their use in the workplace and in practical applications.

2D Transition Metal Carbides (MXene) for Electrochemical Sensing: A Review

MXene, a novel class of 2-dimensional transition metal carbides has evolved as a promising material for various applications owing to its outstanding characteristics such as hydrophilicity, high electrical conductivity, surface area, and attractive topological structure. MXenes can form dispersion in common solvents and constitute composite with other nanomaterials, which can be utilized as effective transducers for molecular sensing. MXene-modified support materials, thus provide an intriguing platform for immobilization of target molecules onto their surface. The literature reveals that it has been increasingly utilized in the sensing of diverse types of analytes including glucose, pharmaceuticals, metals and dyes, cancer markers, pesticides, neurotransmitters, small valuable molecules, and so on. In this review, we summarize the recent updates in the MXene modified materials for sensing. For the convenience of our audience, we have distributed the analytes into categories and discussed them comprehensively. Not only we present the synthesis approach, electrochemical properties and surface chemistry of MXenes but also discussed briefly the current challenges and an outlook for future research in the related area.

Reagentless and sensitive determination of carcinoembryonic antigen based on a stable Prussian blue modified electrode

Reagentless and sensitive detection of tumor biomarkers using label-free electrochemical immunosensors is highly desirable for early and effective cancer diagnosis. Herein, we present a label-free electrochemical immunoassay platform based on surface-confined Prussian blue (PB) redox probes for sensitive and reagentless determination of carcinoembryonic antigen (CEA). To facilitate the electron transfer of probes and improve sensitivity, Au nanoparticles and PB (Au-PB) are electrochemically co-deposited on a carbon nanotube (CNT) modified glassy carbon electrode (GCE). A polydopamine (pDA) layer is coated on the Au-PB nanocomposite layer in situ as a bifunctional linker. In addition to improving the stability of PB, pDA also provides reducibility for the preparation of gold nanoparticles, which offers an interface for anti-CEA antibody immobilization. The fabricated immunosensor has good stability and is able to reagentlessly detect CEA over a wide range (0.005-50 ng mL^-1) with high reproducibility. Furthermore, the immunosensor was used for determination of CEA in human serum samples.

Electrochemical immunomagnetic assay as biosensing strategy for determination of ovarian cancer antigen HE4 in human serum

Prompt cancer diagnosis and treatment represent fundamental aspects to significantly improve patient survival rate. Human epididymis protein 4 (HE4) has recently been identified as promising single serum biomarker of epithelial ovarian cancer with improved diagnostic performances respect to current reference biomarkers. In this study we present the first competitive immunosensing strategy for HE4 determination implemented on magnetic microbeads functionalized with HE4 antigen. A full factorial design and multiple linear regression allowed to find the optimal experimental conditions providing the maximum inhibition rate within the explored domain. Method validation was performed in serum to ensure reliable data to support decision in clinical practice. This method allowed matching the clinically relevant concentration values for the serum biomarker, limits of detection and quantification being 2.8 and 23.0 pM, respectively. Also recovery rate in the 89 ± 7-103 ± 5% range resulted suitable for method applicability for diagnostic purposes.

Immuno-cytometric detection of circulating cell free methylated DNA, post-translationally modified histones and micro RNAs using semi-conducting nanocrystals

The diagnostic potential of cell free epigenomic signatures is largely driven by the fact that manifold quantities of methylated DNA, post-translationally modified histones and micro RNAs are released into systemic circulation in various non-communicable diseases. However, the time-consuming and specificity-related complications of conventional analytical procedures necessitate the development of a method which is rapid, selective and sensitive in nature. The present work illustrates a novel; prompt; "mix and measure" cytometric-based nano-biosensing system that offers direct quantification of cell-free circulating (ccf) epigenomic signatures (methylated ccf-DNA, tri-methylated histone H3 at lysine {4, 9, 27 & 36} and argonaute 2 protein-bound ccf-micro RNAs) using triple nano-assemblies in a single tube format. Each assembly with unique structural and spectral properties comprised of n-type semiconducting nanocrystals conjugated to a specific monoclonal antibody. Our results suggested that the developed combinatorial approach may offer simultaneous detection of three distinct yet biologically interrelated signatures with high selectivity and sensitivity using flow cytometry and fluorometry in the enriched and test samples. The proposed novel nano-assembly based detection system has a considerable potential of emerging as a minimal invasive easy-to-use method that could possibly permit real-time, rapid and reproducible monitoring of epigenomic markers in clinical and field settings.

Reduction and functionalization of graphene oxide with L-cysteine: Synthesis, characterization and biocompatibility

This article presents data on the synthesis, identification, computer simulation and biocompatibility of graphene oxide (GO) functionalized with L-cysteine (GFC). It was determined that GO reacts with L-cysteine in two different ways: in an alkaline medium, L-cysteine reduces functional groups on the surface and at the boundaries of GO; with heating and the use of thionyl chloride, L-cysteine covalently attaches to GO through carboxylic groups only at the boundaries. The identification of GO, reduced graphene oxide and GFC was performed using various physicochemical methods, including infrared spectroscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy and high-resolution transmission electron microscopy. Biocompatibility experiments included erythrocyte hemolysis, platelet aggregation, photodynamic and antiradical activity, binding to human serum albumin, and geno- and cytotoxicity studies. Applying density functional theory and molecular dynamics allowed us to obtain the structural and dynamic characteristics of a GFC-water binary system.

Recent Trends in Electrochemical Sensors for Vital Biomedical Markers Using Hybrid Nanostructured Materials

This work provides a succinct insight into the recent developments in electrochemical quantification of vital biomedical markers using hybrid metallic composite nanostructures. After a brief introduction to the biomarkers, five types of crucial biomarkers, which require timely and periodical monitoring, are shortlisted, namely, cancer, cardiac, inflammatory, diabetic and renal biomarkers. This review emphasizes the usage and advantages of hybrid nanostructured materials as the recognition matrices toward the detection of vital biomarkers. Different transduction methods (fluorescence, electrophoresis, chemiluminescence, electrochemiluminescence, surface plasmon resonance, surface-enhanced Raman spectroscopy) reported for the biomarkers are discussed comprehensively to present an overview of the current research works. Recent advancements in the electrochemical (amperometric, voltammetric, and impedimetric) sensor systems constructed with metal nanoparticle-derived hybrid composite nanostructures toward the selective detection of chosen vital biomarkers are specifically analyzed. It describes the challenges involved and the strategies reported for the development of selective, sensitive, and disposable electrochemical biosensors with the details of fabrication, functionalization, and applications of hybrid metallic composite nanostructures.

The In Vitro Anticancer Activity and Potential Mechanism of Action of 1-[(1R,2S)-2-fluorocyclopropyl]Ciprofloxacin-(4-methyl/phenyl/benzyl-3- aryl)-1,2,4-triazole-5(4H)-thione Hybrids

AIM

Development of 1-[(1R, 2S)-2-fluorocyclopropyl]ciprofloxacin-1,2,4-triazole-5(4H)- thione hybrids as potential dual-acting mechanism anticancer agent to overcome the drug resistance.

BACKGROUND

Chemotherapy is an essential tool for the treatment of lung and female breast cancers, and numerous anticancer agents have been launched for this purpose. However, the clinical outcomes of chemotherapy are usually far from satisfactory due to the side effects and resistance to chemotherapeutic drugs. Thus, it is urgent to develop novel anti-lung and anti-breast cancer agents.

OBJECTIVE

The primary objective of this study was to evaluate the potential of bis-isatin scaffolds with alkyl/ether linkers between the two isatin moieties against different human breast cancer cell lines including A549, MCF-7 and their drug-resistant counterparts A549/CDDP, MCF-7/ADM cells.

METHODS

The 1-[(1R, 2S)-2-fluorocyclopropyl]ciprofloxacin-(4-methyl/phenyl/benzyl-3-aryl)-1,2,4- triazole-5(4H)-thione hybrids were screened for their in vitro activity against drug-sensitive lung (A549), breast (MCF-7) and their drug-resistant counterparts A549/CDDP (cisplatin-resistant), MCF- 7/ADM (doxorubicin-resistant) cancer cell lines by MTT assay. The inhibitory activity of these hybrids against topoisomerase II and EGFR was also evaluated to investigate the potential mechanism of action of these hybrids.

RESULTS

The most prominent hybrid 7k (IC50: 37.28-49.05 µM) was comparable to Vorinostat against A549 and A549/CDDP lung cancer cells, and was 2.79-2.94 times more active than Vorinostat against MCF-7 and MCF-7/ADM breast cancer cell lines. Moreover, hybrid 7k (IC50: 8.6 and 16.4 µM) also demonstrated dual inhibition against topoisomerase II and EGFR.

CONCLUSION

The 1-[(1R, 2S)-2-fluorocyclopropyl]ciprofloxacin-1,2,4-triazole-5(4H)-thione hybrids possess equally activity against both drug-sensitive cancer cells and their drug-resistant counterparts, and the majority of them were no inferior to the reference Vorinostat. The mechanistic study revealed that these hybrids could inhibit both topoisomerase II and EGFR, so these hybrids can be developed as dual-acting mechanism anticancer agents.

Needle stochastic sensors for on-site fast recognition and quantification of biomarkers for gastric cancer in biological samples

N-Doped graphenes recognised CA19-9, CEA, and p53 in biological samples.