MXene supported biomimetic bilayer lipid membrane biosensor for zeptomole detection of BRCA1 gene

Label-free electrochemical immunosensors based on Cu-Ni metal-organic framework and carbon nanotube composite for carcinoembryonic antigen detection

Monitoring cancer biomarkers is of great significance in clinical diagnosis. In this work, a label-free MWCNTs-COOH/CuNi-BTC/FTO electrochemical immunosensor was developed to quantitatively detect carcinoembryonic antigen (CEA). The bimetallic CuNi-BTC showed enhanced current than singe Ni-BTC, and the addition of the MWCNTs-COOH increased the conductivity and further amplified the current signal. The electrode was further modified with CEA antigen (Ag) and bovine serum albumin (BSA) was used to block the non-specific binding sites. Using the emplified current signal of CuNi-BTC, CEA was detected by a DPV method through the current change caused by the specific recognition reaction of Ag and Ab. Under optimal conditions, a range of 0.80-140 ng/mL and a detection limit of 0.046 ng/mL for CEA was obtained. This electrochemical immunosensor possessed good selectivity, reproducibility and long-term stability.

A review towards sustainable analyte detection: Biomimetic inspiration in biosensor technology

The branch of biomimetics has witnessed a profound impact on the field of biosensor technology, reflected in sustainable analyte detection. A vast array of biosensor platforms with improved/upgraded performance have been developed and reported. No wonder the motivation from the field of biomimetics has a huge impact on generating detection systems with escalated degrees of manipulation and tunability at different levels. More recently, biomimetic biosensor technology has found potential in constructing bio-inspired materials such as aptamers, MIPs, nanozymes, DNAzymes, Synzymes, etc. to be integrated with biosensor fabrication. The establishment of a sensing setup is not limited to the bioreceptor fabrication; the construction of transducing element using biomimetic material have been reported too. Moreover, to serve a biosensing of target analyte from a fatal diseased sample different biomimetic architectures can be designed that mimic in-vivo microenvironmental surroundings to get an exact microenvironment equivalent to natural conditions leading towards designing of a precise treatment strategy. This research area is ever-evolving as there is a scope for upgradation and refinement due to advancing technologies including nanotechnology, biomimetic nanomaterials, microfluidics, optical sensors, etc. This review is an attempt to comprehend and juxtapose the very primary innovations in the field of biomimetic biosensor technology to realize its comprehensive and wide-range scope and possibilities.

Selenium nanoparticles modified niobium MXene for non-enzymatic detection of glucose

Glucose sensing remains a crucial need as diabetes is a worldwide concern. This work reports the application of Nb2CTx-selenium nanoparticle composite material for the nonenzymatic sensing of glucose. The surface morphology of the synthesized composite was analyzed using various microscopic techniques like scanning electron microscopy, transmission electron microscopy, and its structural properties were analyzed using diffraction and spectroscopic methods. A gold disc electrode was modified using the nanocomposite and tested for glucose in an alkaline medium. The sensing was based on the oxidation of glucose on the catalytic surface. The glucose was quantified amperometrically at a significantly lower overpotential of 0.16 V. The sensor showed a good detection range from 2 to 30 mM with a sensitivity of 4.15 µA mM-1 cm-2 and a detection limit of 1.1 mM.

Simultaneous detection of breast cancer biomarkers circROBO1 and BRCA1 based on a CRISPR-Cas13a/Cas12a system

Breast cancer is reported to be one of the most lethal cancers in women, and its multi-target detection can help improve the accuracy of diagnosis. In this work, a cluster regularly interspaced short palindromic repeats (CRISPR)-Cas13a/Cas12a-based system was established for the simultaneous fluorescence detection of breast cancer biomarkers circROBO1 and BRCA1. CRISPR-Cas13a and CRISPR-Cas12a were directly activated by their respective targets, resulting in the cleavage of short RNA and DNA reporters, respectively, thus the signals of 6-carboxyfluorescein (FAM) and 6-carboxy-xrhodamine (ROX) were restored. As the fluorescence intensities of FAM and ROX were dependent on the concentrations of circROBO1 and BRCA1, respectively, synchronous fluorescence scanning could achieve one-step detection of circROBO1 and BRCA1 with detection limits of 0.013 pM and 0.26 pM, respectively. The system was highly sensitive and specific, holding high diagnostic potential for the detection of clinical samples. Furthermore, the competing endogenous RNA mechanism between circROBO1 and BRCA1 was also explored, providing a reliable basis for the intrinsic regulatory mechanism of breast cancer.

Characterization and regulation of 2D-3D convertible lipid membrane transformation

Micro-nanomaterials that can adopt different structures are powerful tools in the fields of biological and medical sciences. We previously developed a lipid membrane that can convert between 2D nanosheet and 3D vesicle forms using cationic copolymer polyallylamine-graft-polyethylene glycol and the anionic peptide E5. The properties of the membrane during conversion have been characterized only by confocal laser scan microscopy. Furthermore, due to the 2D symmetry of the lipid nanosheet, the random folding of the lipid bilayer into either the original or the reverse orientation occurs during sheet-to-vesicle conversion, compromising the structural consistency of the membrane. In this study, flow cytometry was applied to track the conversion of more than 5000 lipid membranes from 3D vesicles to 2D nanosheets and back to 3D vesicles, difficult with microscopies. The lipid nanosheets exhibited more side scattering intensity than 3D vesicles, presumably due to free fluctuation and spin of the sheets in the suspension. Furthermore, by immobilizing bovine serum albumin as one of the representative proteins on the outer leaflet of giant unilamellar vesicles at a relatively low coverage, complete restoration of lipid membranes to the original 3D orientation was obtained after sheet-to-vesicle conversion. This convertible membrane system should be applicable in a wide range of fields. Our findings also provide experimental evidence for future theoretical studies on membrane behavior.

MXene-based electrochemical devices applied for healthcare applications

The initial part of the review provides an extensive overview about MXenes as novel and exciting 2D nanomaterials describing their basic physico-chemical features, methods of their synthesis, and possible interfacial modifications and techniques, which could be applied to the characterization of MXenes. Unique physico-chemical parameters of MXenes make them attractive for many practical applications, which are shortly discussed. Use of MXenes for healthcare applications is a hot scientific discipline which is discussed in detail. The article focuses on determination of low molecular weight analytes (metabolites), high molecular weight analytes (DNA/RNA and proteins), or even cells, exosomes, and viruses detected using electrochemical sensors and biosensors. Separate chapters are provided to show the potential of MXene-based devices for determination of cancer biomarkers and as wearable sensors and biosensors for monitoring of a wide range of human activities.

Advances in electrochemical biosensor design for the detection of the stress biomarker cortisol

The monitoring of stress levels in humans has become increasingly relevant, given the recent incline of stress-related mental health disorders, lifestyle impacts, and chronic physiological diseases. Long-term exposure to stress can induce anxiety and depression, heart disease, and risky behaviors, such as drug and alcohol abuse. Biomarker molecules can be quantified in biological fluids to study human stress. Cortisol, specifically, is a hormone biomarker produced in the adrenal glands with biofluid concentrations that directly correlate to stress levels in humans. The rapid, real-time detection of cortisol is necessary for stress management and predicting the onset of psychological and physical ailments. Current methods, including mass spectrometry and immunoassays, are effective for sensitive cortisol quantification. However, these techniques provide only single measurements which pose challenges in the continuous monitoring of stress levels. Additionally, these analytical methods often require trained personnel to operate expensive instrumentation. Alternatively, low-cost electrochemical biosensors enable the real-time detection and continuous monitoring of cortisol levels while also providing adequate analytical figures of merit (e.g., sensitivity, selectivity, sensor response times, detection limits, and reproducibility) in a simple design platform. This review discusses the recent developments in electrochemical biosensor design for the detection of cortisol in human biofluids. Special emphasis is given to biosensor recognition elements, including antibodies, molecularly imprinted polymers (MIPs), and aptamers, as critical components of electrochemical biosensors for cortisol detection. Furthermore, the advantages and limiting factors of various electrochemical techniques and sensing in complex biofluid matrices are overviewed. Remarks on the current challenges and future perspectives regarding electrochemical biosensors for stress monitoring are provided, including matrix effects (pH dependence and biological interferences), wearability, and large-scale production.