Electrospun zirconium oxide embedded in graphene-like nanofiber for aptamer-based impedimetric bioassay toward osteopontin determination

An electrochemical microsensor for osteopontin based on a molecularly imprinted layer and a built-in probe-functionalized acupuncture needle

Osteopontin (OPN) is an important biomarker for reflecting osteoarthritic inflammation and endochondral ossification. In the field of electroanalysis, OPN is a non-electroactive protein, which is usually detected by means of an outer probe or biolabel. Here, a novel microsensor that can directly electroanalyze OPN was constructed by coordinating a surface molecularly imprinted polymer (SMIP) with a built-in electroactive probe of poly(methylene blue) (pMB) on an acupuncture needle microelectrode (ANME). The OPN template can be reversibly anchored using 4-mercaptophenylboronic acid (4-MBPA) via a borate bond between phenylboronic acid and the external cis-diol of the glycoprotein. Methylene blue (MB) and dopamine (DA) were sequentially electropolymerized and grown around templates, which played pivotal roles in the detection signal from the built-in pMB through the imprinted nanocavities. After the recombination of OPN molecules with imprinted nanocavities, the current strength of built-in pMB could be impeded, producing a highly sensitive response. This microsensor shows a linear relationship with the concentration of OPN from 0.01 to 1000 ng mL-1 with a detection limit of 3 pg mL-1. The microsensor also exhibits high selectivity and stability, which is attributed to the recognizing ability of the imprinted nanocavities and the hindrance and anti-interference function of coated polydopamine (pDA). This strategy of preparing a sensor shows practical and scientific significance for functionalizing microelectrodes and constructing microsensors for non-electroactive glycoproteins. In the future, it will be fascinating to integrate this microsensor with the acupuncture technique.

Electrochemical aptasensor based on zirconium/copper oxides embedded in mesoporous carbon derived from bimetallic metal-organic framework for ultrasensitive detection of miR-21

A novel electrochemical aptasensor based on bimetallic zirconium and copper oxides embedded within mesoporous carbon (denoted as ZrO2CuOx@mC) was constructed to detect miRNA. The porous ZrO2CuOx@mC was created through the pyrolysis of bimetallic zirconium/copper-based metal-organic framework (ZrCu-MOF). The substantial surface area and high porosity of ZrO2CuOx@mC nanocomposite along with its robust affinity toward aptamer strands, facilitated the effective anchoring of aptamer strands on the ZrO2CuOx@mC-modified electrode surface. This, coupled with the remarkable electrochemical performance arising from the presence of metal oxides and mesoporous carbon, resulted in the exceptional sensitivity of the ZrO2CuOx@mC-based aptasensor for the detection of miR-21. The prepared aptasensor not only demonstrated a broad detection range from 10 zM to 100 pM, featuring an exceptionally low detection limit of 0.52 zM, but also exhibited notable selectivity against interferences. Moreover, it displayed good stability, reproducibility, and acceptable applicability for miR-21 detection in human serum. The fabricated aptasensor offers a promising platform for ultrasensitive miR-21 detection, with potential applications in accurate and early diagnosis of diseases related to miRNA.

Recent Advances in Biosensor Technology for Early-Stage Detection of Hepatocellular Carcinoma-Specific Biomarkers: An Overview

Hepatocellular carcinoma is currently the most common malignancy of the liver. It typically occurs due to a series of oncogenic mutations that lead to aberrant cell replication. Most commonly, hepatocellular carcinoma (HCC) occurs as a result of pre-occurring liver diseases, such as hepatitis and cirrhosis. Given its aggressive nature and poor prognosis, the early screening and diagnosis of HCC are crucial. However, due to its plethora of underlying risk factors and pathophysiologies, patient presentation often varies in the early stages, with many patients presenting with few, if any, specific symptoms in the early stages. Conventionally, screening and diagnosis are performed through radiological examination, with diagnosis confirmed by biopsy. Imaging modalities tend to be limited by their requirement of large, expensive equipment; time-consuming operation; and a lack of accurate diagnosis, whereas a biopsy's invasive nature makes it unappealing for repetitive use. Recently, biosensors have gained attention for their potential to detect numerous conditions rapidly, cheaply, accurately, and without complex equipment and training. Through their sensing platforms, they aim to detect various biomarkers, such as nucleic acids, proteins, and even whole cells extracted by a liquid biopsy. Numerous biosensors have been developed that may detect HCC in its early stages. We discuss the recent updates in biosensing technology, highlighting its competitive potential compared to conventional methodology and its prospects as a tool for screening and diagnosis.

A disposable paper-based electrochemical biosensor decorated by electrospun cellulose acetate nanofibers for highly sensitive bio-detection

Paper-based electrochemical sensors have the characteristics of flexibility, biocompatibility, environmental protection, low cost, wide availability, and hydropathy, which make them very suitable for the development and application of biological detection. This work proposes electrospun cellulose acetate nanofiber (CA NF)-decorated paper-based screen-printed (PBSP) electrode electrochemical sensors. The CA NFs were directly collected on the PBSP electrode through an electrospinning technique at an optimized voltage of 16 kV for 10 min. The sensor was functionalized with different bio-sensitive materials for detecting different targets, and its sensing capability was evaluated by CV, DPV, and chronoamperometry methods. The test results demonstrated that the CA NFs enhanced the detection sensitivity of the PBSP electrode, and the sensor showed good stability, repeatability, and specificity (p < 0.01, N = 3). The electrochemical sensing of the CA NF-decorated PBSP electrode exhibited a short detection duration of ∼5-7 min and detection ranges of 1 nmol mL-1-100 μmol mL-1, 100 fg mL-1-10 μg mL-1, and 1.5 × 102-106 CFU mL-1 and limits of detection of 0.71 nmol mL-1, 89.1 fg mL-1, and 30 CFU mL-1 for glucose, Ag85B protein, and E. coli O157:H7, respectively. These CA NF-decorated PBSP sensors can be used as a general electrochemical tool to detect, for example, organic substances, proteins, and bacteria, which are expected to achieve point-of-care testing of pathogenic microorganisms and have wide application prospects in biomedicine, clinical diagnosis, environmental monitoring, and food safety.

Aptamers and New Bioreceptors for the Electrochemical Detection of Biomarkers Expressed in Hepatocellular Carcinoma

Hepatocellular carcinoma is a malignancy associated with high mortality and increasing incidence. Early detection of this disease could help increase survival and overall patient benefit. Non-invasive strategies for the diagnosis of this medical condition are of utmost importance. In this scope, the detection of hepatocellular carcinoma biomarkers could provide a useful diagnostic tool. Aptamers represent as short, single-stranded DNAs or RNAs that can specifically bind selected analytes, and also as pseudo-biorecognition elements that can be employed for electrode functionalization. Also, other types of DNA sequences can be used for the construction of DNA-based biosensors applied for the quantification of hepatocellular carcinoma biomarkers. Herein, we will be analyzing recent examples of aptasensors and DNA biosensors for the detection of hepatocellular carcinoma biomarkers like micro-RNAs, long non-coding RNAs, exosomes, circulating tumor cells and proteins. The literature data is discussed comparatively in a critical manner highlighting the advantages of using electrochemical biosensors in diagnosis, as well as the use of nanomaterials and biocomponents in the functionalization of electrodes for improved sensitivity and selectivity.

Research Progress of UiO-66-Based Electrochemical Biosensors

UiO-66, as a member of the MOFs families, is widely employed in sensing, drug release, separation, and adsorption due to its large specific surface area, uniform pore size, easy functionalization, and excellent stability. Especially in electrochemical biosensors, UiO-66 has demonstrated excellent adsorption capacity and response signal, which significantly improves the sensitivity and specificity of detection. However, the existing application research remains in its infancy, lacking systematic methods, and recycling utilization and exclusive sensing of UiO-66 still require further improvement. Therefore, one of the present research objectives is to explore the breakthrough point of existing technologies and optimize the performance of UiO-66-based electrochemical biosensors (UiO-66-EBs). In this work, we summarized current experimental methods and detection mechanisms of UiO-66-EBs in environmental detection, food safety, and disease diagnosis, analyzed the existing problems, and proposed some suggestions to provide new ideas for future research.

Application of Electrospun Nanofibers for Fabrication of Versatile and Highly Efficient Electrochemical Devices: A Review

Electrochemical devices convert chemical reactions into electrical energy or, vice versa, electricity into a chemical reaction. While batteries, fuel cells, supercapacitors, solar cells, and sensors belong to the galvanic cells based on the first reaction, electrolytic cells are based on the reversed process and used to decompose chemical compounds by electrolysis. Especially fuel cells, using an electrochemical reaction of hydrogen with an oxidizing agent to produce electricity, and electrolytic cells, e.g., used to split water into hydrogen and oxygen, are of high interest in the ongoing search for production and storage of renewable energies. This review sheds light on recent developments in the area of electrospun electrochemical devices, new materials, techniques, and applications. Starting with a brief introduction into electrospinning, recent research dealing with electrolytic cells, batteries, fuel cells, supercapacitors, electrochemical solar cells, and electrochemical sensors is presented. The paper concentrates on the advantages of electrospun nanofiber mats for these applications which are mostly based on their high specific surface area and the possibility to tailor morphology and material properties during the spinning and post-treatment processes. It is shown that several research areas dealing with electrospun parts of electrochemical devices have already reached a broad state-of-the-art, while other research areas have large space for future investigations.

Design Strategies for Electrochemical Aptasensors for Cancer Diagnostic Devices

Improved outcomes for many types of cancer achieved during recent years is due, among other factors, to the earlier detection of tumours and the greater availability of screening tests. With this, non-invasive, fast and accurate diagnostic devices for cancer diagnosis strongly improve the quality of healthcare by delivering screening results in the most cost-effective and safe way. Biosensors for cancer diagnostics exploiting aptamers offer several important advantages over traditional antibodies-based assays, such as the in-vitro aptamer production, their inexpensive and easy chemical synthesis and modification, and excellent thermal stability. On the other hand, electrochemical biosensing approaches allow sensitive, accurate and inexpensive way of sensing, due to the rapid detection with lower costs, smaller equipment size and lower power requirements. This review presents an up-to-date assessment of the recent design strategies and analytical performance of the electrochemical aptamer-based biosensors for cancer diagnosis and their future perspectives in cancer diagnostics.