Ultrasensitive electrochemical immunosensor for oral cancer biomarker IL-6 using carbon nanotube forest electrodes and multilabel amplification

Recent advances in bioactive materials: Future perspectives and opportunities in oral cancer biosensing

Bioactive materials and biosensing technologies are emerging as pivotal tools in the early detection and management of oral cancer, a disease characterized by high morbidity and mortality rates. Recent advancements in nanotechnology have facilitated the development of innovative biosensors that utilize bioactive materials for non-invasive diagnostics, particularly through salivary analysis. These biosensors, including electrochemical, optical, and molecular types, target specific biomarkers such as DNA, RNA, and proteins associated with oral cancer. For instance, metal oxide nanoparticles and gold nanoparticles have shown promise in enhancing the sensitivity and specificity of these diagnostic tools. The integration of these nanomaterials allows for real-time monitoring of biomarker levels in saliva, providing a rapid and accurate means of detecting oral cancer at its nascent stages. Furthermore, the utilization of biosensors can circumvent the limitations of traditional biopsy methods, which are often invasive and time-consuming. By focusing on salivary diagnostics, researchers aim to develop point-of-care testing devices that can be used in various settings, thus improving accessibility to early screening for at-risk populations. This innovative approach not only enhances diagnostic accuracy but also holds potential for personalized treatment strategies by enabling continuous monitoring of disease progression and response to therapy. As research continues to evolve, the combination of bioactive materials with advanced biosensing technologies promises to revolutionize oral cancer diagnostics, ultimately leading to improved patient outcomes through earlier intervention and tailored therapeutic approaches.

Functionalized graphitic carbon nitride as an efficient electro-analytical platform for the label-free electrochemical sensing of interleukin-8 in saliva samples

A correlation between the emerging high case fatality rate of head and neck cancer and its propensity to migrate metastatically to other parts of the body makes it a significant global danger. It raises the demand for low-level detection, which is useful for early-stage diagnostics. Graphitic carbon nitride (g-C3N4) has recently garnered considerable attention as a promising nanomaterials for biosensor due to its exceptional redox behavior, electrochemical activity, and abundance of electroactive sites. The current study presents research outcomes regarding the development of an ultra-sensitive platform for detecting interleukin-8 (IL8), a cytokine associated with oral cancer. This investigation involves fabricating the platform using 3-aminopropyl trimethoxysilane (APTES)-functionalized g-C3N4 and assessing its efficacy in both laboratory-made and real samples. The process of g-C3N4 synthesis involved the thermal pyrolysis of urea without any add-on material. Moreover, the APTES@g-C3N4 nanomaterial was subjected to electrophoretic deposition onto an ITO-coated glass electrode. The fabricated APTES@g-C3N4/ITO electrode was covalently immobilized by the EDC and NHS chemical reaction in conjunction with anti-interleukin-8 (anti-IL8) antibodies. Before using these sensors for interleukin-8 (IL8) sensing, the anti-IL8/APTES@g-C3N4/ITO electrode was treated with bovine serum albumin (BSA) molecules utilized to obstruct non-targeted areas. Such a fabricated BSA/anti-IL8/APTES@g-C3N4/ITO electrochemical immunosensing bioelectrode was characterized by various analytical, morphological, and electrochemical techniques to confirm the stepwise fabrication of the sensor. BSA/anti-IL8/APTES@g-C3N4/ITO demonstrates a noticeable DPV based electrochemical response as a function of IL8 in the concentration ranging from 500 fg mL-1 to 160 ng mL-1. This BSA/anti-IL8/APTES@g-C3N4/ITO also exhibits a lower limit of detection (LOD) of 0.04 ng mL-1, a sensitivity of 0.015 mA log10 [ng mL-1] cm-2, and stability for up to 10 weeks. The biosensor demonstrates excellent performance in analyzing real samples, indicating its practical utility. This efficacy can be attributed to the abundance of electroactive sites, confined electronic structures, and strong interactions among the active g-C3N4 matrix, anti-IL8 molecules, and IL8 molecules. Our findings are essential for advancing early and point-of-care diagnostics, where quick turnaround times and great sensitivity are critical.

An electrochemical biosensor for the detection of microRNA-31 as a potential oral cancer biomarker

Oral cancer presents substantial challenges to global health due to its elevated mortality rates. Approximately 90% of these malignancies are oral squamous cell carcinoma (OSCC). A significant contributor to the prevalence of oral cancer is the difficulty in detecting cancerous biomarkers, further exacerbated by socioeconomic disadvantages and late-stage diagnoses. Given the critical nature of oral cancer, the early detection of biomarkers is essential for reducing mortality rates. This study investigates the application of microRNA-31 (miRNA-31) as a biomarker for the electrochemical detection of oral cancer, recognizing the considerable potential that microRNAs have demonstrated in cancer screening and diagnosis. The methodology employed includes the use of a glassy carbon electrode modified with graphene and a molecular tethering agent designed to enhance sensitivity and specificity. The biosensor exhibited a limit of detection of 10- 11 M (70 pg/mL or 6.022 × 106 copies/µL) in buffer and 10- 10 M (700 pg/mL or 6.022 × 107 copies/µL) in diluted serum for the complementary target miRNA-31 using the Six Sigma method. The efficacy of this biosensor was further validated through specificity studies utilizing a non-complementary miRNA in both buffer and human serum samples. The electrochemical biosensor displayed exceptional performance and high sensitivity in detecting miRNA-31, confirming its role as an innovative sensor for the non-invasive diagnosis of oral cancer. Furthermore, the proposed biosensor demonstrates several advantages over current methodologies, including reduced detection time, and cost-effective reagents.

Digital SERS immunoassay of Interleukin-6 based on Au@Ag-Au nanotags

Interleukin-6 (IL-6) is a crucial cytokine involved in inflammation and immune regulation. However, the detection of IL-6 with ultrasensitivity and high specificity remains a significant challenge due to the inherent complexity of biofluids. Herein, we present a digital surface enhanced Raman scattering (SERS) immunoassay using core-shell Au@Ag-Au nanotags for IL-6 detection with ultrasensitivity and high reliability. A low-cost silicon chip was functionalized as capture substrates, employing novel SERS nanotags that exhibit strong, robust and reproducible signals at single-nanoparticle resolution as the amplification element. We proposed two analytical methods to validate single-molecule events follow a Poisson distribution and to quantify protein biomarkers over a broad linear dynamic range, respectively. The strong alignment between theoretical and experimental results enhances the method's reliability. Our assay provides two readouts: colorimetric analysis by naked eyes for high concentrations (>1 ng/mL) and digital SERS analysis for low concentrations. Following method optimization, we obtained a linear range from 100 fg/mL to 1 ng/mL (R2 = 0.994) with a limit of detection (LOD) of 12.4 fg/mL, suitable for clinical applications. The method was tested for IL-6 quantification in healthy human serum and saliva, with recoveries from 92.4% to 105.3%. Finally, the immunoassay demonstrated strong consistency with the standard clinical laboratory method when tested with clinical serum samples. Thus, our proposed the digital SERS immunoassay is a promising tool for the precision clinical diagnosis of IL-6-related diseases or other conditions.

Optical Detection of Interleukin-6 Using Liquid Janus Emulsions Using Hyperthermophilic Affinity Proteins

When equal volumes of two immiscible liquids are mixed (e.g., a hydrocarbon and a fluorocarbon), Janus droplets can form in an aqueous solution. In a gravity-aligned Janus droplet, the boundary between the two phases is flat and thus optically transparent when viewed from above. When tipped due to interactions with an analyte (i.e., agglutination), the resulting change in refraction and reflection yields an optical signal that can be detected and quantified. This study reports the detection and quantitation of interleukin-6 (IL-6) using emulsions functionalized at the hydrocarbon:aqueous interface with engineered proteins that bind IL-6 at high affinity and specificity. Hyperthermophilic affinity proteins (rcSso7d) are derived from thermophiles, giving them excellent thermal stability. Two rcSso7d affinity protein variants were synthesized with a noncanonical azide-functionalized amino acid to enable click chemistry to novel polymeric anchors embedded in the hydrocarbon phase. The two binding proteins recognize different epitopes, enabling the detection of both monomeric and dimeric IL-6 via agglutination. It is noteworthy that the rsSso7d protein variants, in addition to having superior thermal stability and facile recombinant synthesis in E. coli, show superior performance when compared to commercial antibodies for IL-6.

Electrochemical immunomagnetic assay for interleukin-6 detection in human plasma

An electrochemical immunoassay for interleukin-6 (IL-6) was developed based on IL-6 capture using magnetic beads and electrochemical signal production using horseradish peroxidase/tetramethylbenzidine. We achieved IL-6 detection from the 50-1000 pg mL-1 range, which is a physiologically relevant IL-6 range for a variety of biological systems. The sandwich assay performed well in phosphate buffered solution as well as in cellular media and human plasma spiked with IL-6, and decreased time to IL-6 concentration readout to approximately one hour. There is also future potential to apply this assay to real-time point-of-care human disease diagnostics.

Single-Walled Carbon Nanotube-Modified Gold Leaf Immunosensor for Escherichia coli Detection

The requirement to prevent foodborne illnesses underscores the need for reliable detection tools, stimulating biosensor technology with practical solutions for in-field applications. This study introduces a low-cost immunosensor based on a single-walled carbon nanotube (SWCNT)-modified gold leaf electrode (GLE) for the sensitive detection of Escherichia coli. The immunosensor is realized with a layer-by-layer (LbL) assembly technique, creating an electrostatic bond between positively charged polyethylenimine (PEI) and negatively charged carboxyl-functionalized SWCNTs on the GLE. The structural and functional characterization of the PEI-SWCNT film was performed with Raman spectroscopy, high-resolution scanning electron microscopy (HRSEM), and electrical measurements. The PEI-SWCNT film was used as a substrate for antibody immobilization, and the electrochemical sensing potential was validated using electrochemical impedance spectroscopy (EIS). The results showed a wide dynamic range of E. coli detection, 101-108 cfu/mL, with a limit of detection (LOD) of 1.6 cfu/mL in buffer and 15 cfu/mL in the aqueous solution used for cleansing fresh lettuce leaves, affirming its efficiency as a practical and affordable tool in enhancing food safety.

A dual-electrode label-free immunosensor based on in situ prepared Au-MoO3-Chi/porous graphene nanoparticles for point-of-care detection of cholangiocarcinoma

A novel label-free electrochemical immunosensor was prepared for the detection of carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) as biomarkers of cholangiocarcinoma (CCA). A nanocomposite of gold nanoparticles, molybdenum trioxide, and chitosan (Au-MoO3-Chi) was layer-by-layer assembled on the porous graphene (PG) modified a dual screen-printed electrode using a self-assembling technique, which increased surface area and conductivity and enhanced the adsorption of immobilized antibodies. The stepwise self-assembling procedure of the modified electrode was further characterized morphologically and functionally. The electroanalytical detection of biomarkers was based on the interaction between the antibody and antigen of each marker via linear sweep voltammetry using ferrocyanide/ferricyanide as an electrochemical redox indicator. Under optimized conditions, the fabricated immunosensor showed linear relationships between current change (ΔI) and antigen concentrations in two ranges: 0.0025-0.1 U mL-1 and 0.1-1.0 U mL-1 for CA19-9, and 0.001-0.01 ng mL-1 and 0.01-1.0 ng mL-1 for CEA. The limits of detection (LOD) were 1.0 mU mL-1 for CA19-9 and 0.5 pg mL-1 for CEA. Limits of quantitation (LOQ) were 3.3 mU mL-1 for CA19-9 and 1.6 pg mL-1 for CEA. The selectivity of the developed immunosensor was tested on mixtures of antigens and was then successfully applied to determine CA19-9 and CEA in human serum samples, producing satisfactory results consistent with the clinical method.

Nanomaterial Biosensors in Salivary Diagnosis of Oral Cancer: A Scoping Review

Oral cancer is among the highest in the Indian subcontinent. Advanced stages of oral cancer are associated with severe morbidity and higher mortality. Salivary diagnosis is novel and non-invasive. It could be employed on patients even with restricted mouth opening. Hence, an attempt was made to retrieve relevant data regarding this clinically relevant topic.  This article has reviewed metal oxide nanoparticles as a biosensor (BS) in salivary diagnosis for oral cancer. Gold, copper oxide, and carbon nanotubes (CNTs) were used in BS applications. A search from the PUBMED database collection (2004 to 2024) was performed to identify the nanoparticle biomarkers and salivary diagnosis in oral cancer. It revealed 30 articles. All the relevant data was extracted and tabulated in this review. We have discussed the relevance of these BS in salivary diagnosis with their corresponding clinical parameters and sensitivity. We hope that this review summarizes the available literature on this topic and incites dedicated research in prompt and early diagnosis of oral cancer, which directly influences the quality of life outcomes in such patients.

Distance-based paper analytical device for multiplexed quantification of cytokine biomarkers using carbon dots integrated with molecularly imprinted polymer

This article introduces distance-based paper analytical devices (dPADs) integrated with molecularly imprinted polymers (MIPs) and carbon dots (CDs) for simultaneous quantification of cytokine biomarkers, namely C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) in human biological samples for diagnosis of cytokine syndrome. Using fluorescent CDs and MIP technology, the dPAD exhibits high selectivity and sensitivity. Detection is based on fluorescence quenching of CDs achieved through the interaction of the target analytes with the MIP layer on the paper substrate. Quantitative analysis is easily accomplished by measuring the distance length of quenched fluorescence with a traditional ruler and naked eye readout enabling rapid diagnosis of cytokine syndrome and the underlying infection. Our sensor demonstrated linear ranges of 2.50-24.0 pg mL-1 (R2 = 0.9974), 0.25-3.20 pg mL-1 (R2 = 0.9985), and 1.50-16.0 pg mL-1 (R2 = 0.9966) with detection limits (LODs) of 2.50, 0.25, and 1.50 pg mL-1 for CRP, TNF-α, and IL-6, respectively. This sensor also demonstrated remarkable selectivity compared to a sensor employing a non-imprinted polymer (NIP), and precision with the highest relative standard deviation (RSD) of 5.14%. The sensor is more accessible compared to prior methods relying on expensive reagents and instruments and complex fabrication methods. Furthermore, the assay provided notable accuracy for monitoring these biomarkers in various human samples with recovery percentages ranging between 99.22% and 103.58%. By integrating microfluidic systems, nanosensing, and MIPs technology, our developed dPADs hold significant potential as a cost-effective and user-friendly analytical method for point-of-care diagnostics (POC) of cytokine-related disorders. This concept can be further extended to developing diagnostic devices for other biomarkers.

The sensor applications for prostate and lung cancer biomarkers in terms of electrochemical analysis

Prostate and lung cancers are the most common types of cancer and affect a large part of the population around the world, causing deaths. Therefore, the rapid identification of cancer can profoundly impact reducing cancer-related death rates and protecting human lives. Significant resources have been dedicated to investigating new methods for early disease detection. Cancer biomarkers encompass various biochemical entities, including nucleic acids, proteins, sugars, small metabolites, cytogenetic and cytokinetic parameters, and whole tumor cells in bodily fluids. These tools can be utilized for various purposes, such as risk assessment, diagnosis, prognosis, treatment efficacy, toxicity evaluation, and predicting a return. Due to these versatile and critical purposes, there are widespread studies on the development of new, sensitive, and selective approaches for the determination of cancer biomarkers. This review illustrates the significant lung and prostate cancer biomarkers and their determination utilizing electrochemical sensors, which have the advantage of improved sensitivity, low cost, and simple analysis. Additionally, approaches such as improving sensitivity with nanomaterials and ensuring selectivity with MIPs are used to increase the performance of the sensor. This review aims to overview the most recent electrochemical biosensor applications for determining vital biomarkers of prostate and lung cancers in terms of nanobiosensors and molecularly imprinted polymer (MIP)-based biosensors.

COVID-19 cooling: Nanostrategies targeting cytokine storm for controlling severe and critical symptoms

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to wreak havoc worldwide, the "Cytokine Storm" (CS, also known as the inflammatory storm) or Cytokine Release Syndrome has reemerged in the public consciousness. CS is a significant contributor to the deterioration of infected individuals. Therefore, CS control is of great significance for the treatment of critically ill patients and the reduction of mortality rates. With the occurrence of variants, concerns regarding the efficacy of vaccines and antiviral drugs with a broad spectrum have grown. We should make an effort to modernize treatment strategies to address the challenges posed by mutations. Thus, in addition to the requirement for additional clinical data to monitor the long-term effects of vaccines and broad-spectrum antiviral drugs, we can use CS as an entry point and therapeutic target to alleviate the severity of the disease in patients. To effectively combat the mutation, new technologies for neutralizing or controlling CS must be developed. In recent years, nanotechnology has been widely applied in the biomedical field, opening up a plethora of opportunities for CS. Here, we put forward the view of cytokine storm as a therapeutic target can be used to treat critically ill patients by expounding the relationship between coronavirus disease 2019 (COVID-19) and CS and the mechanisms associated with CS. We pay special attention to the representative strategies of nanomaterials in current neutral and CS research, as well as their potential chemical design and principles. We hope that the nanostrategies described in this review provide attractive treatment options for severe and critical COVID-19 caused by CS.

Highly Luminescent Eu3+-Incorporated Zr-MOFs as Fluorescence Sensors for Detection of Hazardous Organic Compounds in Water and Fruit Samples

Considering the risk of toxic organic compounds to both human health and the environment, highly luminescent Eu3+-incorporated amino-functionalized zirconium metal-organic frameworks, namely, Eu/MOF and Eu@MOF were synthesized via the solvothermal method. The synthesized luminescent europium-incorporated MOFs act as outstanding sensor materials for diphenylamine and dinitrobenzene detection in water and fruit samples. The synergistic effect of Eu3+ metal ions and amino-functionalized MOFs enhances the luminescent properties of the MOFs improving the fluorescence sensing ability toward the analytes. The enhancement in the detection capacity of the Eu3+-incorporated sensors than the sole MOF toward toxic organic compounds was confirmed using the Stern-Volmer equation of limit of detection (LOD) measurements along with fluorescence lifetime measurements. The sensors exhibited turn-on fluorometric detection toward their respective analytes due to the inner filter effect. The plausible fluorescence sensing mechanism has been studied. The DFT calculations have been integrated to study the structure, stability, and charge transfer processes.

Nanobioengineered surface comprising carbon based materials for advanced biosensing and biomedical application

Carbon-based nanomaterials (CNMs) are at the cutting edge of materials science. Due to their distinctive architectures, substantial surface area, favourable biocompatibility, and reactivity to internal and/or external chemico-physical stimuli, carbon-based nanomaterials are becoming more and more significant in a wide range of applications. Numerous research has been conducted and still is going on to investigate the potential uses of carbon-based hybrid materials for diverse applications such as biosensing, bioimaging, smart drug delivery with the potential for theranostic or combinatorial therapies etc. This review is mainly focused on the classifications and synthesis of various types of CNMs and their electroanalytical application for development of efficient and ultra-sensitive electrochemical biosensors for the point of care diagnosis of fatal and severe diseases at their very initial stage. This review is mainly focused on the classification, synthesis and application of carbon-based material for biosensing applications. The integration of various types of CNMs with nanomaterials, enzymes, redox mediators and biomarkers have been used discussed in development of smart biosensing platform. We have also made an effort to discuss the future prospects for these CNMs in the biosensing area as well as the most recent advancements and applications which will be quite useful for the researchers working across the globe working specially in biosensors field.

Highly Sensitive Photothermal Microfluidic Thread-Based Duplex Immunosensor for Point-of-Care Monitoring

Herein, we successfully developed a thread-based analytical device (μTAD) for simultaneous immunosensing of two biomolecules with attomolar sensitivity by using a photothermal effect. A photothermal effect exploits a strong light-to-heat energy conversion of plasmonic metallic nanoparticles at localized surface plasmon resonance. The key innovation is to utilize the cotton thread to realize this sensor and the use of chitosan modification for enhancing the microfluidic properties, for improving the efficiency of photothermal conversion, and for sensor stability. The developed μTAD sensor consists of (i) a sample zone, (ii) a conjugation zone coated with gold nanoparticles bound with an antibody (AuNPs-Ab2), and (iii) a test zone immobilized with a capture antibody (anti-Ab1). The prepared μTAD is assembled in a custom three-dimensional (3D) printed device which holds the laser for illumination and the thermometer for readout. The 3D-printed supportive device enhances signal response by focusing light and localizing the heat generated. For proof of concept, simultaneous sensing of two key stress and inflammation biomarkers, namely, cortisol and interleukin-6 (IL-6), are monitored using this technique. Under optimization, this device exhibited a detection linear range of 2.0-14.0 ag/mL (R2 = 0.9988) and 30.0-360.0 fg/mL (R2 = 0.9942) with a detection limit (LOD) of 1.40 ag/mL (∼3.86 amol/L) and 20.0 fg/mL (∼950.0 amol/L) for cortisol and IL-6, respectively. Furthermore, the analysis of both biomolecules in human samples indicated recoveries in the range of 98.8%-102.88% with the highest relative standard deviation being 3.49%, offering great accuracy and precision. These results are the highest reported sensitivity for these analytes using an immunoassay method. Our PT-μTAD strategy is therefore a promising approach for detecting biomolecules in resource-limited point-of-care settings.

Toward the rapid diagnosis of sepsis: dendritic copper nanostructure functionalized diazonium salt modified screen-printed graphene electrode for IL-6 detection

Sepsis, an infectious disease affecting millions of people's health worldwide each year, calls for urgent attention to an improvement of analytical devices. Chemiluminescence immunoassay is a typical diagnostic method utilized to assess the risk development of sepsis. However, due to its high-cost, delayed, and complicated procedure, the practical utilization is therefore undoubtedly limited, especially for point-of-care test. Herein, we fabricated for the first time an immunosensor based on dendritic copper nanostructures (CuNSs) combined with 4-aminobenzoic acid (4-AB, the diazonium salt) as antibody linker modified on a screen-printed graphene electrode for the early detection of the sepsis biomarker interleukin-6 (IL-6). The electrode fabrication is made by electrodeposition, thus eliminating the multistep of nanomaterial synthesis and time wasting. The resulting dendritic CuNSs significantly increase the effective surface area (1.2 times) and the sensor's performance. The morphology of this combination was characterized using CV, EIS, SEM, EDX, and FTIR techniques. In the detection process, the appearance of IL-6 suppresses the current response of the redox probe indicator measured by differential pulse voltammetry due to the antibody-antigen complex. The subtraction of signal (ΔI) was interpreted as IL-6 concentration. This sensor exhibited a linear range from 0.05 to 500 pg mL-1 with low detection limit of 0.02 pg mL-1, proving a possibility for early sepsis screening. In addition, the established immunosensor can successfully quantify IL-6 in human serum sample, in which the results agreed well with those achieved using the standard approach, further showing high practical applicability of this developed immunosensor.

Nano-diagnostics as an emerging platform for oral cancer detection: Current and emerging trends

Globally, oral cancer kills an estimated 150,000 individuals per year, with 300,000 new cases being diagnosed annually. The high incidence rate of oral cancer among the South-Asian and American populations is majorly due to overuse of tobacco, alcohol, and poor dental hygiene. Additionally, socio-economic issues and lack of general awareness delay the primary screening of the disease. The availability of early screening techniques for oral cancer can help in carving out a niche for accurate disease prognosis and also its prevention. However, conventional diagnostic approaches and therapeutics are still far from optimal. Thus, enhancing the analytical performance of diagnostic platforms in terms of specificity and precision can help in understanding the disease progression paradigm. Fabrication of efficient nanoprobes that are sensitive, noninvasive, cost-effective, and less labor-intensive can reduce the global cancer burden. Recent advances in optical, electrochemical, and spectroscopy-based nano biosensors that employ noble and superparamagnetic nanoparticles, have been proven to be extremely efficient. Further, these sensitive nanoprobes can also be employed for predicting disease relapse after chemotherapy, when the majority of the biomarker load is eliminated. Herein, we provide the readers with a brief summary of conventional and new-age oral cancer detection techniques. A comprehensive understanding of the inherent challenges associated with conventional oral cancer detection techniques is discussed. We also elaborate on how nanoparticles have shown tremendous promise and effectiveness in radically transforming the approach toward oral cancer detection. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > In Vitro Nanoparticle-Based Sensing.

Distance-Based All-In-One Immunodevice for Point-of-Care Monitoring of Cytokine Interleukin-6

We report the development of a distance-based paper analytical device combined with a hydrophilic bridge valve (B-dPAD) as a quantitative immunoassay method to monitor human interleukin-6 (IL-6) in human samples. Our device design features (i) a circular sample inlet zone, (ii) a circular capture zone with immobilized anti-IL-6 (anti-Ab₁), and (iii) a detection zone channel coated with methylene blue (MB). Two hydrophilic valves are positioned between these three zones. IL-6 levels were determined quantitatively by measuring the extent of degradation of MB to a colorless product along the length of the detection zone channel. Following method optimization, we obtained a linear range from 0.05 to 25.0 pg/mL (R² = 0.9995) and a detection limit (LOD) of 0.05 pg/mL by the naked-eye readout. This is directly within the clinically relevant range. The system does not require any external instrumentation, and the bridge valves can be easily connected and disconnected by a minimally trained operator. The total analysis time is 35 min, significantly reduced from a typical ELISA assay, which takes around 1 h since the B-dPAD workflow circumvents washing steps. The device was tested for IL-6 quantification in human saliva and urine samples of volunteers, with no significant difference found between our method and the standard clinical laboratory method at 95% confidence levels. Recoveries ranged from 98 to 105% with the highest standard deviation at 3.9%. Our B-dPAD immunodevice is therefore a promising approach for rapid IL-6 monitoring in the context of point-of-care diagnostics and analysis in resource-limited settings.

Synthesis of Metal–Organic Frameworks Quantum Dots Composites as Sensors for Endocrine-Disrupting Chemicals

Hazardous chemical compounds such as endocrine-disrupting chemicals (EDCs) are widespread and part of the materials we use daily. Among these compounds, bisphenol A (BPA) is the most common endocrine-disrupting chemical and is prevalent due to the chemical raw materials used to manufacture thermoplastic polymers, rigid foams, and industrial coatings. General exposure to endocrine-disrupting chemicals constitutes a serious health hazard, especially to reproductive systems, and can lead to transgenerational diseases in adults due to exposure to these chemicals over several years. Thus, it is necessary to develop sensors for early detection of endocrine-disrupting chemicals. In recent years, the use of metal–organic frameworks (MOFs) as sensors for EDCs has been explored due to their distinctive characteristics, such as wide surface area, outstanding chemical fastness, structural tuneability, gas storage, molecular separation, proton conductivity, and catalyst activity, among others which can be modified to sense hazardous environmental pollutants such as EDCs. In order to improve the versatility of MOFs as sensors, semiconductor quantum dots have been introduced into the MOF pores to form metal–organic frameworks/quantum dots composites. These composites possess a large optical absorption coefficient, low toxicity, direct bandgap, formidable sensing capacity, high resistance to change under light and tunable visual qualities by varying the size and compositions, which make them useful for applications as sensors for probing of dangerous and risky environmental contaminants such as EDCs and more. In this review, we explore various synthetic strategies of (MOFs), quantum dots (QDs), and metal–organic framework quantum dots composites (MOFs@QDs) as efficient compounds for the sensing of ecological pollutants, contaminants, and toxicants such as EDCs. We also summarize various compounds or materials used in the detection of BPA as well as the sensing ability and capability of MOFs, QDs, and MOFs@QDs composites that can be used as sensors for EDCs and BPA.

Emerging Biosensors for Oral Cancer Detection and Diagnosis—A Review Unravelling Their Role in Past and Present Advancements in the Field of Early Diagnosis

Oral cancer is a serious concern to people all over the world because of its high mortality rate and metastatic spread to other areas of the body. Despite recent advancements in biomedical research, OC detection at an early stage remains a challenge and is complex and inaccurate with conventional diagnostics procedures. It is critical to study innovative approaches that can enable a faster, easier, non-invasive, and more precise diagnosis of OC in order to increase the survival rate of patients. In this paper, we conducted a review on how biosensors might be an excellent tool for detecting OC. This review covers the strategies that use different biosensors to target various types of biomarkers and focuses on biosensors that function at the molecular level viz. DNA biosensors, RNA biosensors, and protein biosensors. In addition, we reviewed non-invasive electrochemical methods, optical methods, and nano biosensors to analyze the OC biomarkers present in body fluids such as saliva and serum. As a result, this review sheds light on the development of ground-breaking biosensors for the early detection and diagnosis of OC.

Bifunctional Pdots-Based Novel ECL Nanoprobe with Qualitative and Quantitative Dual Signal Amplification Characteristics for Trace Cytokine Analysis

In this work, a novel methodology to design bifunctional ECL-luminophores with self-enhanced and TSA-amplified characteristics was proposed for improving the sensing performance of ECL-immunosensor toward trace cytokine analysis. Thanks to the qualitative- and quantitative- dual signal amplification technique, the as-prepared ECL biosensor demonstrated excellent detection performance. By analyzing the prospective cytokine biomarkers (IL-6), the ECL immunosensor exhibited a broad examination range with quite low detection limit and quite high selectivity, which was far superior to commercial ELISA kits and ever reported works. In particular, the novel ECL nanoprobe developed here could also be applied to monitor other immune toxicities or disease-related cytokines by using the respective antibodies corresponding to these targets. Moreover, the concept and construction strategy of self-amplified ECL-luminophores presented here could be further extended to design a series of Pdots-derived multicolored ECL probes to meet the needs of multipathway detection applications.

Vertically Aligned Carbon Nanotubes as a Unique Material for Biomedical Applications

Vertically aligned carbon nanotubes (VACNTs), a unique classification of CNT, highly oriented and normal to the respective substrate, have been heavily researched over the last two decades. Unlike randomly oriented CNT, VACNTs have demonstrated numerous advantages making it an extremely desirable nanomaterial for many biomedical applications. These advantages include better spatial uniformity, increased surface area, greater susceptibility to functionalization, improved electrocatalytic activity, faster electron transfer, higher resolution in sensing, and more. This Review discusses VACNT and its utilization in biomedical applications particularly for sensing, biomolecule filtration systems, cell stimulation, regenerative medicine, drug delivery, and bacteria inhibition. Furthermore, comparisons are made between VACNT and its traditionally nonaligned, randomly oriented counterpart. Thus, we aim to provide a better understanding of VACNT and its potential applications within the community and encourage its utilization in the future.

Microfluidic electrochemical magnetoimmunosensor for ultrasensitive detection of interleukin-6 based on hybrid of AuNPs and graphene

Cytokines are important factors in the early diagnosis of autoimmune diseases and require high sensitivity, high selectivity and quantitative detection. We proposed a miniaturized electrochemical magneto-immunosensor (EC-MIS) on portable interleukin-6 (IL-6) detection based on this requirement. Firstly, a micro-fabricated working electrode is electrochemically modified with a hybrid of reduced graphene oxide (rGO) and gold nanoparticles (AuNPs). Increased surface area and enhanced charge transfer rate improve the performance of this immunosensor on sensitivity. Secondly, magnetic beads attached with the capture antibody (cAb) are employed in sandwich immunoassay. This kind of immunoassay is immobilized on the working electrode surface by an external magnet to enrich the analyte IL-6. Thirdly, the last two features are combined and integrated on a microfluidic device in order to restrict the sample at certain areas and ease the operation of detection. With our prototypic EC-MIS operated in amperometric mode, we have achieved the detection of IL-6 with a linear range from 0.97 to 250 pg/mL and a limit of detection (LOD) of 0.42 pg/mL. Real serum samples were demonstrated and compared with benchtop equipment's results.

Carbon Nanotube (CNT)-Based Biosensors

This review focuses on recent advances in the application of carbon nanotubes (CNTs) for the development of sensors and biosensors. The paper discusses various configurations of these devices, including their integration in analytical devices. Carbon nanotube-based sensors have been developed for a broad range of applications including electrochemical sensors for food safety, optical sensors for heavy metal detection, and field-effect devices for virus detection. However, as yet there are only a few examples of carbon nanotube-based sensors that have reached the marketplace. Challenges still hamper the real-world application of carbon nanotube-based sensors, primarily, the integration of carbon nanotube sensing elements into analytical devices and fabrication on an industrial scale.

Advances in Nanotechnology-Based Biosensing of Immunoregulatory Cytokines

Cytokines are a large group of small proteins secreted by immune and non-immune cells in response to external stimuli. Much attention has been given to the application of cytokines' detection in early disease diagnosis/monitoring and therapeutic response assessment. To date, a wide range of assays are available for cytokines detection. However, in specific applications, multiplexed or continuous measurements of cytokines with wearable biosensing devices are highly desirable. For such efforts, various nanomaterials have been extensively investigated due to their extraordinary properties, such as high surface area and controllable particle size and shape, which leads to their tunable optical emission, electrical, and magnetic properties. Different types of nanomaterials such as noble metal, metal oxide, and carbon nanoparticles have been explored for various biosensing applications. Advances in nanomaterial synthesis and device development have led to significant progress in pushing the limit of cytokine detection. This article reviews currently used methods for cytokines detection and new nanotechnology-based biosensors for ultrasensitive cytokine detection.

Sensitive Detection of Heregulin-α from Biological Samples Using a Disposable Stochastic Sensor Based on Plasma Deposition of GNPs-AgPs' Nanofilms on Silk

A composite material comprised of graphene nanoplatelet and silver particles (GNPs–AgPs) was used for the deposition of GNPs–AgPs’ nanofilms with cold plasma on silk. α-Cyclodextrin was used as a modifier of the active surface of the disposable sensor. The disposable stochastic sensor was used in screening tests for the assay of heregulin-α in whole blood and tissue samples. The disposable stochastic sensor showed a low limit of determination (4.10 fg mL⁻¹) and can be used with high sensitivity on a wide concentration range (4.10 fg mL⁻¹–0.04 µg mL⁻¹). The screening method was validated against ELISA when good correlations (confirmed also by the t-test) were obtained.

Laser Scribing Fabrication of Graphitic Carbon Biosensors for Label-Free Detection of Interleukin-6

Interleukin-6 (IL-6) is an important immuno-modulating cytokine playing a pivotal role in inflammatory processes in disease induction and progression. As IL-6 serves as an important indicator of disease state, it is of paramount importance to develop low cost, fast and sensitive improved methods of detection. Here we present an electrochemical immunosensor platform based on the use of highly porous graphitic carbon electrodes fabricated by direct laser writing of commercial polyimide tapes and chemically modified with capture IL-6 antibodies. The unique porous and 3D morphology, as well as the high density of edge planes of the graphitic carbon electrodes, resulted in a fast heterogeneous electron transfer (HET) rate, k⁰ = 0.13 cm/s. The resulting immunosensor showed a linear response to log of concentration in the working range of 10 to 500 pg/mL, and low limit of detection (LOD) of 5.1 pg/mL IL-6 in phosphate buffer saline. The total test time was approximately 90 min, faster than the time required for ELISA testing. Moreover, the assay did not require additional sample pre-concentration or labelling steps. The immunosensor shelf-life was long, with stable results obtained after 6 weeks of storage at 4 °C, and the selectivity was high, as no response was obtained in the presence of another inflammatory cytokine, Interlukin-4. These results show that laser-fabricated graphitic carbon electrodes can be used as selective and sensitive electrochemical immunosensors and offer a viable option for rapid and low-cost biomarker detection for point-of-care analysis.

Aptamer and bifunctional enzyme co-functionalized MOF-derived porous carbon for low-background electrochemical aptasensing

To improve the efficiency of aptasensors, a signal amplification strategy by coupling tyrosinase (Tyr)-triggered redox cycling with nanoscale porous carbon (NCZIF) has been proposed. The NCZIF was obtained by calcining ZIF-8 crystals in an inert atmosphere. It had high surface areas, great biocompatibility, and ease of functionalization, which was beneficial for immobilizing sufficient Tyr and aptamer covalently. When the target prostate-specific antigen (PSA) was present, the NCZIF functionalized with Tyr and an aptamer bound to the aptamer-modified Au electrode specifically through the sandwich structure. Then, Tyr acted to oxidize the electroinactive phenol, which led to low-background signal, in the substrate to electroactive catechol, and triggered the redox cycling under the action of NADH. The low detection limit of the proposed electrochemical aptasensor for PSA was 0.01 ng mL^-1, and the wide detection range was from 0.01 to 50 ng mL^-1. The use of ZIF-8 derived porous carbon and Tyr-triggered redox cycling system provided a promising solution for the development of simple, rapid, reliable, and low-background aptasensing methods, which had great potential in the field of disease diagnosis and biomedicine.

Point-of-care detection of cytokines in cytokine storm management and beyond: Significance and challenges

Cytokines are signaling molecules between cells in immune system. Cytokine storm, due to the sudden acute increase in levels of pro-inflammatory circulating cytokines, can result in disease severity and major-organ damage. Thus, there is urgent need to develop rapid, sensitive, and specific methods for monitoring of cytokines in biology and medicine. Undoubtedly, point-of-care testing (POCT) will provide clinical significance in disease early diagnosis, management, and prevention. This review aims to summarize and discuss the latest technologies for detection of cytokines with a focus on POCT. The overview of diseases resulting from imbalanced cytokine levels, such as COVID-19, sepsis and other cytokine release syndromes are presented. The clinical cut-off levels of cytokine as biomarkers for different diseases are summarized. The challenges and perspectives on the development of cytokine POCT devices are also proposed and discussed. Cytokine POCT devices are expected to be the ongoing spotlight of disease management and prevention during COVID-19 pandemic and also the post COVID-19 pandemic era.

PLOD2-driven IL-6/STAT3 signaling promotes the invasion and metastasis of oral squamous cell carcinoma via activation of integrin β1

We previously reported that high expression of procollagen-lysine 2-oxoglutarate 5-dioxygenase 2 (PLOD2) leads to stabilization and plasma membrane translocation of integrin β1 to promote the invasion and metastasis of oral squamous cell carcinoma (SCC). The present study aimed to further understand the relationship between PLOD2-integrin β1 signaling and the tumor microenvironment. This study provided further advanced insights indicating that elevated interleukin (IL)-6 in the tumor microenvironment acts as a key molecule that triggers PLOD2-integrin β1 axis-derived acceleration of tumor invasion and metastasis. It was found using the dual-luciferase reporter assay system that signal transducer and activator of transcription 3 (STAT3) activation by IL-6 was essential for increasing the expression levels of PLOD2 through direct activation of the PLOD2 promoter in oral SCC, whereas IL-6 stimulation did not contribute to integrin β1 expression or the subsequent maturation process towards a functional form on the plasma membrane. Furthermore, the expression of IL-6 in oral SCC tissues was mainly observed in the tumor stroma. Finally, with double immunofluorescence staining, it was found that IL-6 expression occurred in CD163-positive M2 macrophages distributed around the tumor nest. These results combined with our previous results indicate that as IL-6 significantly increases STAT3-mediated PLOD2 promoter activity, IL-6 released by M2-type tumor-associated macrophages is a crucial factor that promotes PLOD2-integrin β1 axis-enhanced invasion and metastasis of oral SCC cells.

Recent advances in point-of-care diagnostics for oral cancer

Early-stage diagnosis is a crucial step in reducing the mortality rate in oral cancer cases. Point-of-care (POC) devices for oral cancer diagnosis hold great future potential in improving the survival rates as well as the quality of life of oral cancer patients. The conventional oral examination followed by needle biopsy and histopathological analysis have limited diagnostic accuracy. Besides, it involves patient discomfort and is not feasible in resource-limited settings. POC detection of biomarkers and diagnostic adjuncts has emerged as non- or minimally invasive tools for the diagnosis of oral cancer at an early stage. Various biosensors have been developed for the rapid detection of oral cancer biomarkers at the point-of-care. Several optical imaging methods have also been employed as adjuncts to detect alterations in oral tissue indicative of malignancy. This review summarizes the different POC platforms developed for the detection of oral cancer biomarkers, along with various POC imaging and cytological adjuncts that aid in oral cancer diagnosis, especially in low resource settings. Various immunosensors and nucleic acid biosensors developed to detect oral cancer biomarkers are summarized with examples. The different imaging methods used to detect oral tissue malignancy are also discussed herein. Additionally, the currently available commercial devices used as adjuncts in the POC detection of oral cancer are emphasized along with their characteristics. Finally, we discuss the limitations and challenges that persist in translating the developed POC techniques in the clinical settings for oral cancer diagnosis, along with future perspectives.

Toward the Rapid Diagnosis of Sepsis: Detecting Interleukin-6 in Blood Plasma Using Functionalized Screen-Printed Electrodes with a Thermal Detection Methodology

This paper reports the detection of the inflammatory and sepsis-related biomarker, interleukin-6 (IL-6), in human blood plasma using functionalized screen-printed electrodes (SPEs) in conjunction with a thermal detection methodology, termed heat-transfer method (HTM). SPEs are functionalized with antibodies specific for IL-6 through electrodeposition of a diazonium linking group and N'-ethylcarbodiimide hydrochloride (EDC) coupling, which was tracked through the use of cyclic voltammetry and Raman spectroscopy. The functionalized SPEs are mounted inside an additively manufactured flow cell and connected to the HTM device. We demonstrate the ability to detect IL-6 at clinically relevant concentrations in PBS buffer (pH = 7.4) with no significant interference from the similarly sized sepsis-related biomarker procalcitonin (PCT). The limit of detection (3σ) of the system is calculated to correspond to 3.4 ± 0.2 pg mL^-1 with a working range spanning the physiologically relevant concentration levels in both healthy individuals and patients with sepsis, indicating the sensitivity of the sensor is suitable for the application. Further experiments helped provide a proof-of-application through the detection of IL-6 in blood plasma with no significant interference observed from PCT or the constituents of the medium. Due to the selectivity, sensitivity, straightforward operation, and low cost of production, this sensor platform has the potential for use as a traffic light sensor for the multidetection of inflammatory biomarkers for the diagnosis of sepsis and other conditions in which the rapid testing of blood biomarkers has vital clinical application.

Recent Advances in Nano-Bio-Sensing Fabrication Technology for the Detection of Oral Cancer

Nanotechnology-based miniaturized devices have been a breakthrough in the pre-clinical and clinical research areas, e.g. drug delivery, personalized medicine. They have revolutionized the discovery and development of biomarker-based diagnostic devices for detection of various diseases such as tuberculosis, malaria and cancer. Nanomaterials (NMs) hold tremendous diagnostic potential due to their high surface-to-volume ratio and quantum confinement phenomenon, improving the detection limit of clinically relevant biomolecules in bio-fluids. Thus, they are helpful in the translation of bench-on platform to point-of-care (POC) screening device. The nanomaterial-based biosensor fabrication technology has also simplified and improved oral cancer (OC) or oral squamous cell carcinomas (OSCC) diagnosis. The fabrication of nano-bio sensors involves application specific modifications of NMs. The unique properties functionalized NMs have augmented their application on the nano-biosensing platform for the detection of clinically relevant biomolecules in bio-fluids. Therefore, this article summarizes the recent advancements in the process of fabrication of nano-biosensors for detection of OC.

Nanostructures for Biosensing, with a Brief Overview on Cancer Detection, IoT, and the Role of Machine Learning in Smart Biosensors

Biosensors are essential tools which have been traditionally used to monitor environmental pollution and detect the presence of toxic elements and biohazardous bacteria or virus in organic matter and biomolecules for clinical diagnostics. In the last couple of decades, the scientific community has witnessed their widespread application in the fields of military, health care, industrial process control, environmental monitoring, food-quality control, and microbiology. Biosensor technology has greatly evolved from in vitro studies based on the biosensing ability of organic beings to the highly sophisticated world of nanofabrication-enabled miniaturized biosensors. The incorporation of nanotechnology in the vast field of biosensing has led to the development of novel sensors and sensing mechanisms, as well as an increase in the sensitivity and performance of the existing biosensors. Additionally, the nanoscale dimension further assists the development of sensors for rapid and simple detection in vivo as well as the ability to probe single biomolecules and obtain critical information for their detection and analysis. However, the major drawbacks of this include, but are not limited to, potential toxicities associated with the unavoidable release of nanoparticles into the environment, miniaturization-induced unreliability, lack of automation, and difficulty of integrating the nanostructured-based biosensors, as well as unreliable transduction signals from these devices. Although the field of biosensors is vast, we intend to explore various nanotechnology-enabled biosensors as part of this review article and provide a brief description of their fundamental working principles and potential applications. The article aims to provide the reader a holistic overview of different nanostructures which have been used for biosensing purposes along with some specific applications in the field of cancer detection and the Internet of things (IoT), as well as a brief overview of machine-learning-based biosensing.

Nanostructure-Based Electrochemical Immunosensors as Diagnostic Tools

Electrochemical immunosensors are affinity-based biosensors characterized by several useful features such as specificity, miniaturizability, low cost and simplicity, making them very interesting for many applications in several scientific fields. One of the significant issues in the design of electrochemical immunosensors is to increase the system’s sensitivity. Different strategies have been developed, one of the most common is the use of nanostructured materials as electrode materials, nanocarriers, electroactive or electrocatalytic nanotracers because of their abilities in signal amplification and biocompatibility. In this review, we will consider some of the most used nanostructures employed in the development of electrochemical immunosensors (e.g., metallic nanoparticles, graphene, carbon nanotubes) and many other still uncommon nanomaterials. Furthermore, their diagnostic applications in the last decade will be discussed, referring to two relevant issues of present-day: the detection of tumor markers and viruses.

Revisiting Electrochemical Biosensing in the 21st Century Society for Inflammatory Cytokines Involved in Autoimmune, Neurodegenerative, Cardiac, Viral and Cancer Diseases

The multifaceted key roles of cytokines in immunity and inflammatory processes have led to a high clinical interest for the determination of these biomolecules to be used as a tool in the diagnosis, prognosis, monitoring and treatment of several diseases of great current relevance (autoimmune, neurodegenerative, cardiac, viral and cancer diseases, hypercholesterolemia and diabetes). Therefore, the rapid and accurate determination of cytokine biomarkers in body fluids, cells and tissues has attracted considerable attention. However, many currently available techniques used for this purpose, although sensitive and selective, require expensive equipment and advanced human skills and do not meet the demands of today’s clinic in terms of test time, simplicity and point-of-care applicability. In the course of ongoing pursuit of new analytical methodologies, electrochemical biosensing is steadily gaining ground as a strategy suitable to develop simple, low-cost methods, with the ability for multiplexed and multiomics determinations in a short time and requiring a small amount of sample. This review article puts forward electrochemical biosensing methods reported in the last five years for the determination of cytokines, summarizes recent developments and trends through a comprehensive discussion of selected strategies, and highlights the challenges to solve in this field. Considering the key role demonstrated in the last years by different materials (with nano or micrometric size and with or without magnetic properties), in the design of analytical performance-enhanced electrochemical biosensing strategies, special attention is paid to the methods exploiting these approaches.

Impedimetric Detection of Femtomolar Levels of Interleukin6, Interleukin 8, and Tumor Necrosis Factor Alpha Based on Thermally Modified Nanotubular Titanium Dioxide Arrays

An inexpensive, easy to prepare, and label-free electrochemical impedance spectroscopy-based biosensor has been developed for the selective detection of human interleukin 6 (IL-6), interleukin 8 (CXCL8, IL-8), and tumor necrosis factor (TNFα)-potential inflammatory cancer biomarkers. We describe a, so far, newly developed and unexplored method to immobilize antibodies onto a titanium dioxide nanotube (TNT) array by physical adsorption. Immobilization of anti-IL-6, anti-IL-8, and anti-TNFα on TNT and the detection of human IL-6, IL-8, and TNFα were examined using electrochemical impedance spectroscopy (EIS). The impedimetric immunosensor demonstrates good selectivity and high sensitivity against human biomarker analytes and can detect IL-6, IL-8, and TNFα at concentrations as low as 5 pg/mL, equivalent to the standard concentration of these proteins in human blood. The calibration curves evidenced that elaborated biosensors are sensitive to three cytokines within 5 ÷ 2500 pg/mL in the 0.01 M phosphate-buffered saline solution (pH 7.4).

Antibody Micropatterned Lubricant-Infused Biosensors Enable Sub-Picogram Immunofluorescence Detection of Interleukin 6 in Human Whole Plasma

Recent studies have shown a correlation between elevated interleukin 6 (IL-6) concentrations and the risk of respiratory failure in COVID-19 patients. Therefore, detection of IL-6 at low concentrations permits early diagnosis of worst-case outcome in viral respiratory infections. Here, a versatile biointerface is presented that eliminates nonspecific adhesion and thus enables immunofluorescence detection of IL-6 in whole human plasma or whole human blood during coagulation, down to a limit of detection of 0.5 pg mL^-1 . The sensitivity of the developed lubricant-infused biosensor for immunofluorescence assays in detecting low molecular weight proteins such as IL-6 is facilitated by i) producing a bioink in which the capture antibody is functionalized by an epoxy-based silane for covalent linkage to the fluorosilanized surface and ii) suppressing nonspecific adhesion by patterning the developed bioink into a lubricant-infused coating. The developed biosensor addresses one of the major challenges for biosensing in complex fluids, namely nonspecific adhesion, therefore paving the way for highly sensitive biosensing in complex fluids.

Nanotechnology-based drug delivery systems for enhanced diagnosis and therapy of oral cancer

Oral cancer is a common malignant life-threatening tumor. Despite some advances in traditional therapy, mortality and mobidity rates are high due to delayed diagnosis and ineffective treatment. Additionally, some patients inevitably suffer from various fatal adverse effects during the course of therapy. Therefore, it is imperative to develop novel methods to eradicate oral cancer cells with minimal adverse effects on normal cells. Nanotechnology is a promising and novel vehicle for the diagnosis and treatment of oral cancer with encouraging recent achievements. In this review, we present state-of-the-art nanotechnology-based drug delivery systems employed in the domain of oral cancer, especially for its enhanced diagnosis and therapy. We describe in detail the types of nanotechnology used in the management of oral cancer and summarize administration routes of nanodrugs. Finally, the potential and prospects of nanotechnology-based drug delivery systems as promising modalities of diagnosis and therapy of oral cancer are highlighted.

Printed Electrodes in Microfluidic Arrays for Cancer Biomarker Protein Detection

Medical diagnostics is trending towards a more personalized future approach in which multiple tests can be digitized into patient records. In cancer diagnostics, patients can be tested for individual protein and genomic biomarkers that detect cancers at very early stages and also be used to monitor cancer progression or remission during therapy. These data can then be incorporated into patient records that could be easily accessed on a cell phone by a health care professional or the patients themselves on demand. Data on protein biomarkers have a large potential to be measured in point-of-care devices, particularly diagnostic panels that could provide a continually updated, personalized record of a disease like cancer. Electrochemical immunoassays have been popular among protein detection methods due to their inherent high sensitivity and ease of coupling with screen-printed and inkjet-printed electrodes. Integrated chips featuring these kinds of electrodes can be built at low cost and designed for ease of automation. Enzyme-linked immunosorbent assay (ELISA) features are adopted in most of these ultrasensitive detection systems, with microfluidics allowing easy manipulation and good fluid dynamics to deliver reagents and detect the desired proteins. Several of these ultrasensitive systems have detected biomarker panels ranging from four to eight proteins, which in many cases when a specific cancer is suspected may be sufficient. However, a grand challenge lies in engineering microfluidic-printed electrode devices for the simultaneous detection of larger protein panels (e.g., 50-100) that could be used to test for many types of cancers, as well as other diseases for truly personalized care.

A Review: Electrochemical Biosensors for Oral Cancer

Oral cancer poses a serious threat worldwide owing to its soaring case-fatality rate and its metastatic characteristics of spreading to the other parts of the body. Despite the recent breakthroughs in biomedical sciences, the detection of oral cancer at an early stage is still challenging. Conventional diagnosis in clinics and optical techniques to detect oral cancer in the initial stages are quite complicated as well as not completely accurate. To enhance the survival rate of oral cancer patients, it is important to investigate the novel methodologies that can provide faster, simpler, non-invasive, and yet ultraprecise detection of the onset of oral cancer. In this review, we demonstrate the promising aspects of an electrochemical biosensor as an ideal tool for oral cancer detection. We discuss the cutting-edge methodologies utilizing various electrochemical biosensors targeting the different kinds of biomarkers. In particular, we emphasize on electrochemical biosensors working at the molecular levels, which can be classified into mainly three types: DNA biosensors, RNA biosensors and protein biosensors according to the types of the analytes. Furthermore, we focus on the significant electrochemical methods including cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) to analyze the oral cancer biomarkers (such as IL-6, IL-8, CYFRA 21-1, CD 59 and CIP2A) present in body fluids including saliva and serum, using non-invasive manner. Hence, this review provides essential insights into the development of pioneering electrochemical biosensors for the detection of oral cancer at an early stage.