An ultrasensitive Cystatin C renal failure immunosensor based on a PPy/CNT electrochemical capacitor grafted on interdigitated electrode

Emerging trends in the cystatin C sensing technologies: towards better chronic kidney disease management

Cystatin C (CysC), a protein, has replaced creatinine as a biomarker of kidney function and other diseases and has led to a surge in the research on the development of efficient CysC biosensors. The current CysC sensing technologies are remarkable in terms of selectivity and reproducibility. However, the complexity, cost, and space requirements of these methods render them unsuitable for real-time monitoring or point-of-care (PoC) implementations in healthcare settings. This review discusses the most recent developments in the field of CysC biosensing and to the best of our knowledge, this is the first focused review exclusively on CysC biosensing modalities. Our goal is to provide a thorough overview of the current state of CysC biosensors, and presenting mechanisms related to biosensor recognition and transduction. The review starts with clinical significance of CysC detection followed by detailed analysis of different CysC biosensing methods with emphasis on the necessity of PoC monitoring of CysC. We have also highlighted current challenges and an outlook on future perspectives. We anticipate that this study will play a key role in the understanding the working principle of CysC sensors and will aid in the designing of new efficient sensing modalities for the detection of CysC.

Electrochemical and optical methods for detection of cystatin C as a biomarker of kidney disease

The kidneys have vital functions in the body, including maintaining homeostasis and blood pressure, controlling water-electrolyte balance, and eliminating metabolic wastes. Early identification of renal dysfunction disease and selection of effective treatment methods reduce mortality in patients. Nowadays, Common indicators of kidney function lack the necessary specificity and sensitivity, but recent studies have reported that cystatin C (CysC) may be an ideal marker for glomerular filtration. CysC, known as a cysteine protease inhibitor, is synthesized by nucleated cells and is easily filtered due to its positive charge and low molecular weight. Also, the synthesis and secretion of CysC is a stable process that is not affected by dietary factors, enhanced protein catabolism, and renal conditions. Various studies have reported that measuring the level of CysC in the body's biological fluids is necessary for the treatment and diagnosis of a wide range of diseases, especially chronic kidney disease (CKD).Despite evidence that positive correlation between the high risk and/or progression of CKD and CysC, it's applied in clinical practice is still rare. Biosensors have been widely developed and researched as an effective method for the pharmaceutical, environmental, and medical fields. Biosensors are designed to create an effective electronic signal commensurate with the concentration of a particular biochemical.Recently, many studies have used biosensor techniques to detect CysC in kidneys and other diseases. In this study, we attempt to examine studies that have used different biosensor techniques for the detect CysC.

An electrochemical immunosensor for sensitive and rapid detection of cystatin C based on Fe3O4/AuNPs-MWCNTs@PDA nanocomposite

Serum Cystatin C (CysC) is an impressive marker for early diagnosis of renal dysfunction. In this work, we established a novel electrochemical immunosensor based on Fe3O4/AuNPs-MWCNTs@PDA nanocomposite for the detection of CysC. The Fe3O4/AuNPs-MWCNTs@PDA nanozyme complex by polydopamine encapsulation can not only carry massive detection antibodies, but also bind the electroactive substance toluidine blue (TB) through electrostatic adsorption. By immobilizing AuNPs onto the electrode to bind the capture antibody (Ab1), we constructed a sandwich electrochemical immunosensor with low cost, high sensitivity, and repeatability. The detection range is 3.9-125.0 ng/mL with a significant linear relationship between the current peak difference (ip) and logarithm of the CysC concentration. Moreover, the detection limit of the immunosensor is 0.157 ng/mL. We have successfully utilized this novel immunosensor to detect CysC in human serum samples, and these results have implications for its potential use in clinical application.

Biological and technical factors affecting the point-of-care diagnostics in not-oncological chronic diseases

Inexpensive point-of-care (POC) analytical solutions have the potential to allow the implementation of large-scale screening campaigns aimed at identifying the initial stages of pathologies in the population, reducing morbidity, mortality and, indirectly, also the costs for the healthcare system. At global level, the most common preventive screening schemes address some cancer pathologies or are used to monitor the spread of some infective diseases. However, systematic testing might become decisive to improve the care response even in the case of chronic pathologies and, in this review, we analyzed the state-of-the-art of the POC diagnostics for Chronic Kidney Disease, Chronic Obstructive Pulmonary Disease and Multiple Sclerosis. The different technological options used to manufacture the biosensors and evaluate the produced data have been described and this information has been integrated with the present knowledge relatively to the biomarkers that have been proposed to monitor such diseases, namely their availability and reliability. Finally, the nature of the macromolecules used to capture the biomarkers has been discussed in relation to the biomarker nature.

Tailoring molecularly imprinted polymer on titanium-multiwalled carbon nanotube functionalized gold electrode for enhanced chlorophyll determination in microalgae health assessment

A unique method for determining chlorophyll content in microalgae is devised employing a gold interdigitated electrode (G-IDE) with a 10-µm gap, augmented by a nano-molecularly imprinted polymer (nano-MIP) and a titanium dioxide/multiwalled carbon nanotube (TiO2/MWCNT) nanocomposite. The nano-MIP, produced using chlorophyll template voids, successfully trapped chlorophyll, while the TiO2/MWCNT nanocomposite, synthesized by the sol-gel technique, exhibited a consistent distribution and anatase crystalline structure. The rebinding of procured chlorophyll powder, which was used as a template for nano-MIP synthesis, was identified with a high determination coefficient (R2 = 0.9857). By combining the TiO2/MWCNT nanocomposite with nano-MIP, the G-IDE sensing method achieved a slightly better R2 value of 0.9892 for detecting chlorophyll in microalgae. The presented G-IDE sensor showed a significant threefold enhancement in chlorophyll detection compared with commercially available chlorophyll powder. It had a detection limit of 0.917 mL (v/v) and a linear range that spanned from 10-6 to 1 mL. The effectiveness of the sensor in detecting chlorophyll in microalgae was confirmed through validation of its repeatability and reusability.

Highly Stable Flexible Organic Electrochemical Transistors with Natural Rubber Latex Additives

Organic electrochemical transistors (OECTs) have attracted considerable interest in the context of wearable and implantable biosensors due to their remarkable signal amplification combined with seamless integration into biological systems. These properties underlie OECTs' potential utility across a range of bioelectronic applications. One of the main challenges to their practical applications is the mechanical limitation of PEDOT:PSS, the most typical conductive polymer used as a channel layer, when the OECTs are applied to implantable and stretchable bioelectronics. In this work, we address this critical issue by employing natural rubber latex (NRL) as an additive in PEDOT:PSS to improve flexibility and stretchability of the OECT channels. Although the inclusion of NRL leads to a decrease in transconductance, mainly due to a reduced carrier mobility from 0.3 to 0.1 cm2/V·s, the OECTs maintain satisfactory transconductance, exceeding 5 mS. Furthermore, it is demonstrated that the OECTs exhibit excellent mechanical stability while maintaining their performance even after 100 repetitive bending cycles. This work, therefore, suggests that the NRL/PEDOT:PSS composite film can be deployed for wearable/implantable applications, where high mechanical stability is needed. This finding opens up new avenues for practical use of OECTs in more robust and versatile wearable and implantable biosensors.

AuNPs-BP-MWCNTs-COOH-based electrochemical immunosensor for the determination of deoxynivalenol in wheat flour

Deoxynivalenol (DON) has drawn considerable attention for its obvious pathogenicity and wide use in agro-products, which cause a potential threat to human health. In this work, an electrochemical immunosensor is developed for the highly sensitive and selective detection of DON in wheat flour using AuNPs-BP-MWCNTs-COOH and antibodies. The AuNPs-BP-MWCNTs-COOH nanocomposite was prepared via an in situ reduction reaction and ultrasonic-assisted liquid-phase exfoliation. The nanocomposite exhibits a larger surface area, decent stability, excellent electron transfer capability, good protein binding capability and prominent specificity. The plentiful carboxyl group on the nanocomposite can bind to the amino group of the antibody, and AuNPs have an affinity for the sulfhydryl group of the antibody, which makes it feasible for the nanocomposite to load the antibody. The peak currents are plotted against the logarithm of DON concentration from 0.002 to 80 ng mL-1 with a limit of detection (LOD) of 0.5 pg mL-1. This approach establishes an effective label-free immunosensor platform for the detection of DON with high sensitivity and selectivity in various food and agricultural products.

Highly Efficient Photoelectrochemical Detection of Cystatin C Based on a Core-Shell MOF Nanocomposite with Biomimetic-Catalysis Amplification

Cystatin C (CysC) has been proven to be used to diagnose acute kidney injury (AKI) rapidly and sensitively early. Therefore, it is urgent to develop a sensitive, novel, and rapid method for detecting CysC. In this work, a novel photoelectrochemical (PEC) biosensor was designed for ultrasensitive CysC detection. Ti-MOF@DM-LZU1@Au as a photosensitive material was first modified on the ITO electrode surface. Then, Ab1 and CysC were assembled on the electrode via the specific immunoresponse of an antigen and antibody. Lastly, the conjugate Ab2/l-Cys bilayer/l-Cys-hemin/G-quadruplex with self-catalytic enzyme performance, as a signal amplification approach, could further react with CysC and Ab1, which resulted in a stronger photocurrent. As expected, the constructed PEC sensor realized the ultrasensitive detection of CysC, with a detection range of 10 pg/mL to 16 μg/mL and a lower limit of 8.023 pg/mL. The biosensor had excellent repeatability, selectivity, and stability. Moreover, it can provide a new method for the sensitive and rapid detection of other protein molecules in clinical practice.

Phospholipid-functionalized gold electrode for cellular membrane interface studies - interactions between DMPC bilayer and human cystatin C

This work describes the electrochemical studies on the interactions between V57G mutant of human cystatin C (hCC V57G) and membrane bilayer immobilized on the surface of a gold electrode. The electrode was modified with 6-mercaptohexan-1-ol (MCH) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). DMPC was used as a membrane mimetic for monitoring electrochemical changes resulting from the interactions between the functionalized electrode surface and human cystatin C. The interactions between the modified electrode and hCC V57G were investigated by cyclic voltammetry and electrochemical impedance spectroscopy in a phosphate buffered saline (PBS) containing Fe(CN)63-/4- as a redox probe. The electrochemical measurements confirm that fabricated electrode is sensitive to hCC V57G at the concentration of 1 × 10-14 M. The incubation studies carried out at higher concentrations resulted in insignificant changes observed in cyclic voltammetry and electrochemical impedance spectroscopy measurements. The calculated values of surface coverage θR confirm that the electrode is equally covered at higher concentrations of hCC V57G. Measurements of wettability and surface free energy made it possible to determine the influence of individual structural elements of the modified gold electrode on its properties, and thus allowed to understand the nature of the interactions. Contact angle values confirmed the results obtained during electrochemical measurements, indicating the sensitivity of the electrode towards hCC V57G at the concentration of 1 × 10-14 M. In addition, the XPS spectra confirmed the successful anchoring of hCC V57G to the DMPC-functionalized surface.

Design and development of opto-electrochemical biosensing devices for diagnosing chronic kidney disease

Chronic kidney disease (CKD) is emerging as one of the major causes of the increase in mortality rate and is expected to become 5th major cause by 2050. Many studies have shown that it is majorly related to various risk factors, and thus becoming one of the major health issues around the globe. Early detection of renal disease lowers the overall burden of disease by preventing individuals from developing kidney impairment. Therefore, diagnosis and prevention of CKD are becoming the major challenges, and in this situation, biosensors have emerged as one of the best possible solutions. Biosensors are becoming one of the preferred choices for various diseases diagnosis as they provide simpler, cost-effective and precise methods for onsite detection. In this review, we have tried to discuss the globally developed biosensors for the detection of CKD, focusing on their design, pattern, and applicability in real samples. Two major classifications of biosensors based on transduction systems, that is, optical and electrochemical, for kidney disease have been discussed in detail. Also, the major focus is given to clinical biomarkers such as albumin, creatinine, and others related to kidney dysfunction. Furthermore, the globally developed sensors for the detection of CKD are discussed in tabulated form comparing their analytical performance, response time, specificity as well as performance in biological fluids.

Nanotechnology-Based Drug Delivery Systems in the Transdermal Treatment of Melanoma

The incidence rate of melanoma is dramatically increasing worldwide, raising it to the fifth most common cancer in men and the sixth in women currently. Resistance generally occurs to the agents used in chemotherapy; besides their high toxicity destroys the normal cells. This study reviewed a detailed summary of the structure, advantages, and disadvantages of nanotechnology-based drug delivery systems in the treatment of melanoma, as well as some nanocarrier applications in animal models or clinical studies. Respective databases were searched for the target keywords and 93 articles were reviewed and discussed. A close study of the liposomes, niosomes, transferosomes, ethosomes, transethosomes, cubosomes, dendrimers, cyclodextrins, solid lipid nanoparticles, and carbon nanotubes (CNTs) was conducted. It was found that these nanocarriers could inhibit metastasis and migration of melanoma cells and decrease cell viability. Conclusively, some nanocarriers like liposomes, niosomes, and transferosomes have been discussed as superior to conventional therapies for melanoma treatment.

Ultrasensitive Silicon Nanowire Biosensor with Modulated Threshold Voltages and Ultra-Small Diameter for Early Kidney Failure Biomarker Cystatin C

Acute kidney injury (AKI) is a frequently occurring severe disease with high mortality. Cystatin C (Cys-C), as a biomarker of early kidney failure, can be used to detect and prevent acute renal injury. In this paper, a biosensor based on a silicon nanowire field-effect transistor (SiNW FET) was studied for the quantitative detection of Cys-C. Based on the spacer image transfer (SIT) processes and channel doping optimization for higher sensitivity, a wafer-scale, highly controllable SiNW FET was designed and fabricated with a 13.5 nm SiNW. In order to improve the specificity, Cys-C antibodies were modified on the oxide layer of the SiNW surface by oxygen plasma treatment and silanization. Furthermore, a polydimethylsiloxane (PDMS) microchannel was involved in improving the effectiveness and stability of detection. The experimental results show that the SiNW FET sensors realize the lower limit of detection (LOD) of 0.25 ag/mL and have a good linear correlation in the range of Cys-C concentration from 1 ag/mL to 10 pg/mL, exhibiting its great potential in the future real-time application.

ZnO-Based Electrochemical Immunosensor to Assess Vaccine-Induced Antibody-Mediated Immunity against Wild-Type and Gamma SARS-CoV-2 Strains

The evaluation of serological responses to COVID-19 is crucial for population-level surveillance, developing new vaccines, and evaluating the efficacy of different immunization programs. Research and development of point-of-care test technologies remain essential to improving immunity assessment, especially for SARS-CoV-2 variants that partially evade vaccine-induced immune responses. In this work, an impedimetric biosensor based on the immobilization of the recombinant trimeric wild-type spike protein (S protein) on zinc oxide nanorods (ZnONRs) was employed for serological evaluation. We successfully assessed its applicability using serum samples from spike-based COVID-19 vaccines: ChAdOx1-S (Oxford-AstraZeneca) and BNT162b2 (Pfizer-BioNTech). Overall, the ZnONRs/ spike-modified electrode displayed accurate results for both vaccines, showing excellent potential as a tool for assessing and monitoring seroprevalence in the population. A refined outcome of this technology was achieved when the ZnO immunosensor was functionalized with the S protein from the P.1 linage (Gamma variant). Serological responses against samples from vaccinated individuals were acquired with excellent performance. Following studies based on traditional serological tests, the ZnONRs/spike immunosensor data reveal that ChAdOx1-S vaccinated individuals present significantly less antibody-mediated immunity against the Gamma variant than the BNT162b2 vaccine, highlighting the great potential of this point-of-care technology for evaluating vaccine-induced humoral immunity against different SARS-CoV-2 strains.

Carbon-based biosensors from graphene family to carbon dots: A viewpoint in cancer detection

According to the latest report by International Agency for Research on Cancer, 19.3 million new cancer cases and 10 million cancer deaths were globally reported in 2020. Early diagnosis can reduce these numbers significantly, and biosensors have appeared to be a solution to this problem as, unlike the traditional methods, they have low cost, rapid process, and do not need experts present on site for use. These devices have been incorporated to detect many cancer biomarkers and measure cancer drug delivery. To design these biosensors, a researcher must know about their different types, properties of nanomaterials, and cancer biomarkers. Among all types of biosensors, electrochemical and optical biosensors are the most sensitive and promising sensors for detecting complicated diseases like cancer. The carbon-based nanomaterial family has attracted lots of attention due to their low cost, easy preparation, biocompatibility, and significant electrochemical and optical properties. In this review, we have discussed the application of graphene and its derivatives, carbon nanotubes (CNTs), carbon dots (CDs), and fullerene (C60), for designing different electrochemical and optical cancer-detecting biosensors. Furthermore, the application of these carbon-based biosensors for detecting seven widely studied cancer biomarkers (HER2, CEA, CA125, VEGF, PSA, Alpha-fetoprotein, and miRNA21) is reviewed. Finally, various fabricated carbon-based biosensors for detecting cancer biomarkers and anticancer drugs are comprehensively summarized as well.

Recent Advances in Electrochemical Immunosensors with Nanomaterial Assistance for Signal Amplification

Electrochemical immunosensors have attracted immense attention due to the ease of mass electrode production and the high compatibility of the miniature electric reader, which is beneficial for developing point-of-care diagnostic devices. Electrochemical immunosensors can be divided into label-free and label-based sensing strategies equipped with potentiometric, amperometric, voltammetric, or impedimetric detectors. Emerging nanomaterials are frequently used on electrochemical immunosensors as a highly rough and conductive interface of the electrodes or on nanocarriers of immobilizing capture antibodies, electroactive mediators, or catalyzers. Adopting nanomaterials can increase immunosensor characteristics with lower detection limits and better sensitivity. Recent research has shown innovative immobilization procedures of nanomaterials which meet the requirements of different electrochemical immunosensors. This review discusses the past five years of advances in nanomaterials (metal nanoparticles, metal nanostructures, carbon nanotubes, and graphene) integrated into the electrochemical immunosensor. Furthermore, the new tendency and endeavors of nanomaterial-based electrochemical immunosensors are discussed.

Micro and Nano Interdigitated Electrode Array (IDEA)-Based MEMS/NEMS as Electrochemical Transducers: A Review

Micro and nano interdigitated electrode array (µ/n-IDEA) configurations are prominent working electrodes in the fabrication of electrochemical sensors/biosensors, as their design benefits sensor achievement. This paper reviews µ/n-IDEA as working electrodes in four-electrode electrochemical sensors in terms of two-dimensional (2D) planar IDEA and three-dimensional (3D) IDEA configurations using carbon or metal as the starting materials. In this regard, the enhancement of IDEAs-based biosensors focuses on controlling the width and gap measurements between the adjacent fingers and increases the IDEA's height. Several distinctive methods used to expand the surface area of 3D IDEAs, such as a unique 3D IDEA design, integration of mesh, microchannel, vertically aligned carbon nanotubes (VACNT), and nanoparticles, are demonstrated and discussed. More notably, the conventional four-electrode system, consisting of reference and counter electrodes will be compared to the highly novel two-electrode system that adopts IDEA's shape. Compared to the 2D planar IDEA, the expansion of the surface area in 3D IDEAs demonstrated significant changes in the performance of electrochemical sensors. Furthermore, the challenges faced by current IDEAs-based electrochemical biosensors and their potential solutions for future directions are presented herein.

An ultrasensitive electrochemical immunosensor for hepatitis C antibodies based on one-step-eletrosynthetized polypyrrole-graphene nanocomposite

An ultrasensitive label-free electrochemical immunosensor was developed for hepatitis C antibodies (anti-HCV). Worldwide, it is estimated 71 million people have HCV infection in a chronic stage that may lead to cirrose and cancer. To achieve HCV elimination, health programs should include screening testing based on anti-HCV detection allowing the early-stage treatment. The immunosensor was based on a graphene oxide-polypyrrole (PPy-GO) film one-step electropolymerized on the electrode surface. Ultrasensitive anti-HCV detection was ensured by HCV antigen conjugated to biotin that was immobilized in a great amount on streptavidin-coated nanostructured surface. Analytical responses were obtained by anodic peaks from the square wave voltammetry in the presence of ferrocyanide/ferricyanide as a redox probe. This immunosensor exhibited a linear range from 2 to 14 ng mL^-1 of anti-HCV and a limit of detection in the clinical range (1.63 ng mL^-1). Furthermore, the immunosensor presented an efficient performance for the determination of anti-HCV in spiked serum samples, becoming this developed nanosensor as potential tools for early HCV diagnosis and screening.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10853-022-06992-5.

Aptasensing nucleocapsid protein on nanodiamond assembled gold interdigitated electrodes for impedimetric SARS-CoV-2 infectious disease assessment

In an aim of developing portable biosensor for SARS-CoV-2 pandemic, which facilitates the point-of-care aptasensing, a strategy using 10 μm gap-sized gold interdigitated electrode (AuIDE) is presented. The silane-modified AuIDE surface was deposited with ∼20 nm diamond and enhanced the detection of SARS-CoV-2 nucleocapsid protein (NCP). The characteristics of chemically modified diamond were evidenced by structural analyses, revealing the cubic crystalline nature at (220) and (111) planes as observed by XRD. XPS analysis denotes a strong interaction of carbon element, composed ∼95% as seen in EDS analysis. The C-C, CC, CO, CN functional groups were well-refuted from XPS spectra of carbon and oxygen elements in diamond. The interrelation between elements through FTIR analysis indicates major intrinsic bondings at 2687-2031 cm-1. The aptasensing was evaluated through electrochemical impedance spectroscopy measurements, using NCP spiked human serum. With a good selectivity the lower detection limit was evidenced as 0.389 fM, at a linear detection range from 1 fM to 100 pM. The stability, and reusability of the aptasensor were demonstrated, showing ∼30% and ∼33% loss of active state, respectively, after ∼11 days. The detection of NCP was evaluated by comparing anti-NCP aptamer and antibody as the bioprobes. The determination coefficients of R2 = 0.9759 and R2 = 0.9772 were obtained for aptamer- and antibody-based sensing, respectively. Moreover, the genuine interaction of NCP aptamer and protein was validated by enzyme linked apta-sorbent assay. The aptasensing strategy proposed with AuIDE/diamond enhanced sensing platform is highly recommended for early diagnosis of SARS-CoV-2 infection.

NS1 glycoprotein detection in serum and urine as an electrochemical screening immunosensor for dengue and Zika virus

The incidence of infection by the dengue virus (DENV) has grown dramatically, reaching 128 countries in tropical and subtropical regions worldwide, with a pattern of hyper-endemicity. DENV is a mosquito-borne disease having four serotypes, one or two circulating in epidemic outbreaks. The diagnosis of DENV is challenging mainly due to the circulation of new viruses with remarkable similarities, such as Zika (ZIKV) that may cause fetal microcephaly. DENV affects 390 million people per year, but these numbers may be higher due to the underreported and misclassified cases. Recently, the NS1 nonstructural protein has been described in serum and urine of DENV and ZIKV patients, suggesting its use as a biomarker for screening since a negative NS1 sample confirms the absence of these infections. Herein, a label-free immunosensor comprising an assembled nanostructured thin film of carbon nanotube-ethylenediamine is described. The advantage of in situ electrosynthesis of polymer film is to allow major control of thickness and conductivity, in addition to designing the reactive groups for functionalization. A quartz crystal microbalance system was used to estimate the thickness of the polymeric film obtained. The anti-NS1 monoclonal antibodies were immobilized to carbon nanotubes by covalent linkage, permitting a high stability during measurements. Analytical responses to NS1 were obtained by differential pulse voltammetry (DPV), showing a linear range from 20 to 800 ng mL^-1 and reproducibility of 3.0%, with a limit of detection (LOD) of 6.8 ng mL^{- 1}. This immunosensor was capable of detecting ZIKV and DENV NS1 in spiked urine and real serum in a clinical range.Graphical abstract.

Plastic Antibody of Polypyrrole/Multiwall Carbon Nanotubes on Screen-Printed Electrodes for Cystatin C Detection

This work reports the design of a novel plastic antibody for cystatin C (Cys-C), an acute kidney injury biomarker, and its application in point-of-care (PoC) testing. The synthetic antibody was obtained by tailoring a molecularly imprinted polymer (MIP) on a carbon screen-printed electrode (SPE). The MIP was obtained by electropolymerizing pyrrole (Py) with carboxylated Py (Py-COOH) in the presence of Cys-C and multiwall carbon nanotubes (MWCNTs). Cys-C was removed from the molecularly imprinted poly(Py) matrix (MPPy) by urea treatment. As a control, a non-imprinted poly(Py) matrix (NPPy) was obtained by the same procedure, but without Cys-C. The assembly of the MIP material was evaluated in situ by Raman spectroscopy and the binding ability of Cys-C was evaluated by the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) electrochemical techniques. The MIP sensor responses were measured by the DPV anodic peaks obtained in the presence of ferro/ferricyanide. The peak currents decreased linearly from 0.5 to 20.0 ng/mL of Cys-C at each 20 min successive incubation and a limit of detection below 0.5 ng/mL was obtained at pH 6.0. The MPPy/SPE was used to analyze Cys-C in spiked serum samples, showing recoveries <3%. This device showed promising features in terms of simplicity, cost and sensitivity for acute kidney injury diagnosis at the point of care.

Nanocarrier-Based Drug Delivery for Melanoma Therapeutics

Melanoma, as a tumor cell derived from melanocyte transformation, has the characteristics of malignant proliferation, high metastasis, rapid recurrence, and a low survival rate. Traditional therapy has many shortcomings, including drug side effects and poor patient compliance, and so on. Therefore, the development of an effective treatment is necessary. Currently, nanotechnologies are a promising oncology treatment strategy because of their ability to effectively deliver drugs and other bioactive molecules to targeted tissues with low toxicity, thereby improving the clinical efficacy of cancer therapy. In this review, the application of nanotechnology in the treatment of melanoma is reviewed and discussed. First, the pathogenesis and molecular targets of melanoma are elucidated, and the current clinical treatment strategies and deficiencies of melanoma are then introduced. Following this, we discuss the main features of developing efficient nanosystems and introduce the latest reports in the literature on nanoparticles for the treatment of melanoma. Subsequently, we review and discuss the application of nanoparticles in chemotherapeutic agents, immunotherapy, mRNA vaccines, and photothermal therapy, as well as the potential of nanotechnology in the early diagnosis of melanoma.

DNAzyme concatemer-catalyzed precipitation on an interdigitated micro-comb electrode for capacitance immunosensing of interleukin-6 with rolling circle amplification

A novel capacitance immunosensor based on DNAzyme concatemer-amplified signal-generation tags was developed for the sensitive detection of interleukin-6 (IL-6) on an interdigitated micro-comb electrode.

Advances in immunosensor technology

In recent years, advances in immunosensor device fabrication have significantly expanded the use of this technology in a broad range of applications including clinical diagnosis, food analysis, quality control, environmental studies and industrial monitoring. The most important aspect in fabrication is to obtain a design that provides a low detection limit. The utilization of nanomaterials as a label, catalyst and biosensing transducer is, perhaps, the most popular approach in ultrasensitive devices. This chapter reviews recent advances in immunosensor fabrication and summarizes the most recent studies. Strategies employed to significantly improve sensitivity and specificity of immunosensor technology and the advantages and limitations thereof are explored.