Recent advances in salivary cancer diagnostics enabled by biosensors and bioelectronics

Bioinspired Materials for Wearable Devices and Point-of-Care Testing of Cancer

Wearable, point-of-care diagnostics, and biosensors are on the verge of bringing transformative changes in detection, management, and treatment of cancer. Bioinspired materials with new forms and functions have frequently been used, in both translational and commercial spaces, to fabricate such diagnostic platforms. Engineered from organic or inorganic molecules, bioinspired systems are naturally equipped with biorecognition and stimuli-sensitive properties. Mechanisms of action of bioinspired materials are deeply connected with thermodynamically or kinetically controlled self-assembly at the molecular and supramolecular levels. Thus, integration of bioinspired materials into wearable devices, either as triggers or sensors, brings about unique device properties usable for detection, capture, or rapid readout for an analyte of interest. In this review, we present the basic principles and mechanisms of action of diagnostic devices engineered from bioinspired materials, describe current advances, and discuss future trends of the field, particularly in the context of cancer.

Biosensors for saliva biomarkers

The analysis of salivary biomarkers has gained interest and is advantageous for simple, safe, and non-invasive testing in diagnosis as well as treatment. This chapter explores the importance of saliva biomarkers and summarizes recent advances in biosensor fabrication. The identification of diagnostic, prognostic and therapeutic markers in this matrix enables more rapid and frequent testing when combined with the use of biosensor technology. Challenges and future goals are highlighted and examined.

Saliva diagnostics: emerging techniques and biomarkers for salivaomics in cancer detection

INTRODUCTION

The pursuit of easy-to-use, non-invasive and inexpensive diagnostics is an urgent task for clinicians and scientists. Saliva is an important component of body fluid with regular changes of contents under various pathophysiological conditions, and the biomarkers identified from saliva shows high application potentials and values in disease diagnostics. This review introduces the latest developments in saliva research, with an emphasis on the detection and application of salivary biomarkers in cancer detection.

AREAS COVERED

Detection of disease-specific biomarkers in saliva samples by existing salivaomic methods can be used to diagnose various human pathological conditions and was introduced in details. This review also covers the saliva collection methods, the analytical techniques as well as the corresponding commercial products, with an aim to describe an holistic process for saliva-based diagnostics.

EXPERT OPINION

Saliva, as a non-invasive and collectable body fluid, can reflect the pathophysiological changes of the human body to a certain extent. Identification of reliable saliva biomarkers can provide a convenient way for cancer detection in clinical applications.

Salivary biomarkers of neurodegenerative and demyelinating diseases and biosensors for their detection

Salivary analysis is gaining increasing interest as a novel and promising field of research for the diagnosis of neurodegenerative and demyelinating diseases related to aging. The collection of saliva offers several advantages, being noninvasive, stress-free, and repeatable. Moreover, the detection of biomarkers directly in saliva could allow an early diagnosis of the disease, leading to timely treatments. The aim of this manuscript is to highlight the most relevant researchers' findings relatively to salivary biomarkers of neurodegenerative and demyelinating diseases, and to describe innovative and advanced biosensing strategies for the detection of salivary biomarkers. This review is focused on five relevant aging-related neurodegenerative disorders (Alzheimer's disease, Parkinson's disease, Amyotrophic Lateral Sclerosis, Huntington's disease, Multiple Sclerosis) and the salivary biomarkers most commonly associated with them. Advanced biosensors enabling molecular diagnostics for the detection of salivary biomarkers are presented, in order to stimulate future research in this direction and pave the way for their clinical application.

A movable type bioelectronics printing technology for modular fabrication of biosensors

Biosensors have been widely used in various fields such as food industry, environmental testing and medical testing for their high sensitivity. However, current fabrication methods of biosensors, such as screen printing, micro fabrication and 3D printing suffer from complex procedures, requirement of cleanroom facility and limited fabrication materials, which significantly restrict the development and utilization of biosensors. Here, we propose a movable type bioelectronics printing method for the fabrication of biosensors by directly transferring bioelectronic materials onto various substrates using pre-fabricated molds. This simple, low-cost, yet robust method facilitates on-demand printing of master molds of partial or complete circuits on both rigid or flexible substrates. With this method, bioactive materials such as enzymes can be directly transferred onto substrates together with other electronic components, without complex modification after electrode fabrication using conventional methods. For demonstration, a dual-channel flexible electrochemical biosensor was fabricated by the movable type bioelectronics printing method for continuous monitoring of glucose and lactate. The movable type bioelectronics printing technology holds advantages of repeatability, flexibility and low cost for fabrication of biosensors on rigid and flexible substrates, as well as direct transfer printing of bioactive materials, which greatly promotes small-scale production of biosensors.

Malignancies and Biosensors: A Focus on Oral Cancer Detection through Salivary Biomarkers

Oral cancer is among the deadliest types of malignancy due to the late stage at which it is usually diagnosed, leaving the patient with an average five-year survival rate of less than 50%. The booming field of biosensing and point of care diagnostics can, in this regard, play a major role in the early detection of oral cancer. Saliva is gaining interest as an alternative biofluid for non-invasive diagnostics, and many salivary biomarkers of oral cancer have been proposed. While these findings are promising for the application of salivaomics tools in routine practice, studies on larger cohorts are still needed for clinical validation. This review aims to summarize the most recent development in the field of biosensing related to the detection of salivary biomarkers commonly associated with oral cancer. An introduction to oral cancer diagnosis, prognosis and treatment is given to define the clinical problem clearly, then saliva as an alternative biofluid is presented, along with its advantages, disadvantages, and collection procedures. Finally, a brief paragraph on the most promising salivary biomarkers introduces the sensing technologies commonly exploited to detect oral cancer markers in saliva. Hence this review provides a comprehensive overview of both the clinical and technological advantages and challenges associated with oral cancer detection through salivary biomarkers.

Salivary miR-30c-5p as Potential Biomarker for Detection of Oral Squamous Cell Carcinoma

The levels of different classes of extracellular RNAs (exRNAs) remain stable in bodily fluids. The detection of either enriched or depleted specific subsets of salivary microRNAs (miRNAs) has the potential to serve as a non-invasive approach for biomarker development. Thus, salivary miRNAs have emerged as a promising molecular tool for early diagnosis and screening of oral squamous cell carcinoma (OSCC). Total RNA was extracted from saliva supernatant of 33 OSCC patients and 12 controls (discovery set), and the differential expression of 8 cancer-related miRNAs was detected by TaqMan assay. Among the screened miRNAs, miR-30c-5p (p < 0.04) was significantly decreased in OSCC saliva. The same transcriptional behavior of miR30c-5p was observed in an additional validation set. miR-30c-5p showed a significant statistical difference between cases and controls with areas under the curve (AUC) of 0.82 (95% CI: 0.71–0.89). The sensitivity and the specificity of miR-30c-5p were 86% and 74%, respectively. The target identification analysis revealed enrichment of miR-30c-5p targets in p53 and Wnt signaling pathways in OSCC. Additionally, the miR-30c-5p targets had clinical significance related to overall survival. In conclusion, these findings show that downregulated miR-30c-5p has the potential to serve as a novel, non-invasive biomarker for early OSCC detection.

Saliva, a bodily fluid with recognized and potential diagnostic applications

Human whole saliva is a bodily fluid that can be obtained easily by noninvasive techniques. Specimens can be collected by the patient also at home in order to monitor health status and variations of several analytes of clinical interest. The contributions to whole saliva include secretions from salivary glands and, among others, from the gingival crevicular fluid that derives from the epithelial mucosa. Therefore, saliva is currently a relevant diagnostic fluid for many substances, including steroids, nonpeptide hormones, therapeutic drugs, and drugs of abuse. This review at first briefly describes the different contributions to whole saliva. A section illustrates the procedures for the collection, handling, and storage of salivary specimens. Another section describes the present use of whole saliva for diagnostic purposes and its specific utilization for the diagnosis of several local and systemic diseases. The final sections illustrate the future opportunities offered by various not conventional techniques with a focus on the most recent –omic investigations. It describes the various issues that have to be taken into account to avoid false positives and negatives, such as the strength of the experimental plan, the adequacy of the number of samples under study, and the proper choice of controls.

Immunosensor Based on Zinc Oxide Nanocrystals Decorated with Copper for the Electrochemical Detection of Human Salivary Alpha-Amylase

(1) Background: Nanocrystals (NCs)-based electrochemical sensors have been proposed for biomarkers detection, although immunosensors using ZnO NCs decorated with copper are still scarce. (2) Methods: Electrochemical immunodetection of human salivary alpha-amylase (HSA) used ZnO, CuO, and ZnO:xCu (x = 0.1, 0.4, 1.0, 4.0, and 12.0) NCs. (3) Results: Substitutional incorporation of Cu2+ in the crystalline structure of ZnO and formation of nanocomposite were demonstrated by characterization. Graphite electrodes were used and the electrochemical signal increased by 40% when using ZnO:1Cu and 4Cu (0.25 mg·mL-1), in an immunosensor (0.372 mg·mL-1 of anti-alpha-amylase and 1% of casein). Different interactions of HSA with the alpha-amylase antibody were registered when adding the NCs together, either before or after the addition of saliva (4 μL). The immunosensor changed specificity due to the interaction of copper. The ZnO:1Cu and ZnO:4Cu samples showed 50% interference in detection when used before the addition of saliva. The immunosensor showed 100% specificity and a sensitivity of 0.00196 U·mL-1. (4) Conclusions: Results showed that the order of NCs addition in the sensors should be tested and evaluated to avoid misinterpretation in detection and to enable advances in the validation of the immunosensor.

Toward nanobioelectronic medicine: Unlocking new applications using nanotechnology

Bioelectronic medicine aims to interface electronic technology with biological components and design more effective therapeutic and diagnostic tools. Advances in nanotechnology have moved the field forward improving the seamless interaction between biological and electronic components. In the lab many of these nanobioelectronic devices have the potential to improve current treatment approaches, including those for cancer, cardiovascular disorders, and disease underpinned by malfunctions in neuronal electrical communication. While promising, many of these devices and technologies require further development before they can be successfully applied in a clinical setting. Here, we highlight recent work which is close to achieving this goal, including discussion of nanoparticles, carbon nanotubes, and nanowires for medical applications. We also look forward toward the next decade to determine how current developments in nanotechnology could shape the growing field of bioelectronic medicine. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > Biosensing.

Recent advances in graphene-based nanobiosensors for salivary biomarker detection

As biosensing research is rapidly advancing due to significant developments in materials, chemistry, and electronics, researchers strive to build cutting-edge biomedical devices capable of detecting health-monitoring biomarkers with high sensitivity and specificity. Biosensors using nanomaterials are highly promising because of the wide detection range, fast response time, system miniaturization, and enhanced sensitivity. In the recent development of biosensors and electronics, graphene has rapidly gained popularity due to its superior electrical, biochemical, and mechanical properties. For biomarker detection, human saliva offers easy access with a large variety of analytes, making it a promising candidate for its use in point-of-care (POC) devices. Here, we report a comprehensive review that summarizes the most recent graphene-based nanobiosensors and oral bioelectronics for salivary biomarker detection. We discuss the details of structural designs of graphene electronics, use cases of salivary biomarkers, the performance of existing sensors, and applications in health monitoring. This review also describes current challenges in materials and systems and future directions of the graphene bioelectronics for clinical POC applications. Collectively, the main contribution of this paper is to deliver an extensive review of the graphene-enabled biosensors and oral electronics and their successful applications in human salivary biomarker detection.

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.

Printed Organic Transistor-based Biosensors for Non-invasive Sweat Analysis

This review describes recent advances in biosensors for non-invasive human healthcare applications, especially focusing on sweat analysis, along with approaches for fabricating these biosensors based on printed electronics technology. Human sweat contains various kinds of biomarkers. The relationship between a trace amount of sweat biomarkers partially partitioned from blood and diseases has been investigated by omic analysis. Recent progress in wearable or portable biosensors has enabled periodic or continuous monitoring of some sweat biomarkers while supporting the results of the omic analysis. In this review, we particularly focused on a transistor-based biosensor that is highly sensitive in quantitatively detecting the low level of sweat biomarkers. Furthermore, we showed a new approach of flexible hybrid electronics that has been applied to advanced sweat biosensors to realize fully integrated biosensing systems wirelessly connected to a networked IoT system. These technologies are based on uniquely advanced printing techniques that will facilitate mass fabrication of high-performance biosensors at low cost for future smart healthcare.

Bioelectronic Medicine: From Preclinical Studies on the Inflammatory Reflex to New Approaches in Disease Diagnosis and Treatment

Bioelectronic medicine is an evolving field in which new insights into the regulatory role of the nervous system and new developments in bioelectronic technology result in novel approaches in disease diagnosis and treatment. Studies on the immunoregulatory function of the vagus nerve and the inflammatory reflex have a specific place in bioelectronic medicine. These studies recently led to clinical trials with bioelectronic vagus nerve stimulation in inflammatory diseases and other conditions. Here, we outline key findings from this preclinical and clinical research. We also point to other aspects and pillars of interdisciplinary research and technological developments in bioelectronic medicine.

Saliva and Oral Diseases

Saliva is a fascinating biological fluid which has all the features of a perfect diagnostic tool. In fact, its collection is rapid, simple, and noninvasive. Thanks to several transport mechanisms and its intimate contact with crevicular fluid, saliva contains hundreds of proteins deriving from plasma. Advances in analytical techniques have opened a new era-called "salivaomics"-that investigates the salivary proteome, transcriptome, microRNAs, metabolome, and microbiome. In recent years, researchers have tried to find salivary biomarkers for oral and systemic diseases with various protocols and technologies. The review aspires to provide an overall perspective of salivary biomarkers concerning oral diseases such as lichen planus, oral cancer, blistering diseases, and psoriasis. Saliva has proved to be a promising substrate for the early detection of oral diseases and the evaluation of therapeutic response. However, the wide variation in sampling, processing, and measuring of salivary elements still represents a limit for the application in clinical practice.

Exosome-specific tumor diagnosis via biomedical analysis of exosome-containing microRNA biomarkers

Exosome-containing microRNAs (exomiRs) can be employed as potential biomarkers for tumor diagnosis and have drawn much attention in the past few years. However, the separation of exosomes and the detection of exomiRs are still inconvenient or even difficult to implement. Thus, it is important to develop a simple, accurate, and reliable strategy for the separation of exosomes and the biomedical analysis of exomiRs. Herein, a novel exosome-specific tumor diagnosis strategy was constructed by integrating the rapid magnetic exosome-enrichment platform and the Ru(bpy)32+-polymer amplified electrochemiluminescence (ECL) strategy. This strategy realized the rapid and efficient capture of tumor-derived exosomes through a biological-affinity identification platform of the EpCAM antibody. The biomedical analysis of exomiRs achieved a preferable specificity and high sensitivity of 103 particles. Furthermore, we investigated the performance index for clinical blood samples from tumor patients; the results indicated that the exosome-specific tumor diagnosis strategy readily and consistently responded to exomiRs. These results indicated that the exosome-specific tumor diagnosis strategy provided new opportunities for the sensitive and efficient analysis of tumor-derived exomiRs. This strategy greatly simplified the biomedical analysis process and established the non-destructive detection mode of fluid biopsy for tumors.

Salivary exosomal miR-24-3p serves as a potential detective biomarker for oral squamous cell carcinoma screening

OBJECTIVES

miRNAs in salivary exosomes are used as novel non-invasive biomarkers for detection strategies of human disease. Here, we aimed to investigate the diagnostic potential of salivary exosomal miRNAs as biomarkers for screening oral squamous cell carcinoma (OSCC) and to explore the underlying mechanisms of OSCC pathogenesis.

MATERIALS AND METHODS

Differentially expressed miRNAs were obtained from salivary exosomes of four healthy controls and four OSCC patients using miRNA microarray analysis. The expression of miR-24-3p in the salivary exosomes was then verified by qRT-PCR. The diagnostic power was assessed by receiver operating characteristic (ROC) analysis. Cell proliferation was measured using CCK-8 cell viability assay and colony formation assay. The target gene of miR-24-3p was confirmed by dual luciferase reporter assay.

RESULTS

A total of 109 miRNAs were found to be more than 2-fold altered in the salivary of patients and healthy individuals by miRNA microarray. qRT-PCR analysis further confirmed a significant increase of miR-24-3p in the salivary exosomes from 45 preoperative OSCC patients compared to 10 normal controls. ROC analysis showed that miR-24-3p has excellent diagnostic accuracy for OSCC (area under the ROC curve [AUC] = 0.738; P =  0.02). Similarly, we found that miR-24-3p expressed a higher level in OSCC neoplastic tissues, suggesting that circulating miR-24-3p may originate from tumor cells. Furthermore, exogenous exosomal miR-24-3p increased proliferation of recipient malignant cells. Additionally, overexpression of miR-24-3p promoted the proliferation of OSCC cells and regulated the expression of cell cycle-related genes. Dual luciferase reporter assay indicated that miR-24-3p can interact with PER1 directly.

CONCLUSIONS

Salivary exosomal miR-24-3p is a potential novel diagnostic biomarker for OSCC, and miR-24-3p can maintain the proliferation of OSCC cells through targeting PER1.

Advances in diagnostic microfluidics

Microfluidics is an emerging field in diagnostics that allows for extremely precise fluid control and manipulation, enabling rapid and high-throughput sample processing in integrated micro-scale medical systems. These platforms are well-suited for both standard clinical settings and point-of-care applications. The unique features of microfluidics-based platforms make them attractive for early disease diagnosis and real-time monitoring of the disease and therapeutic efficacy. In this chapter, we will first provide a background on microfluidic fundamentals, microfluidic fabrication technologies, microfluidic reactors, and microfluidic total-analysis-systems. Next, we will move into a discussion on the clinical applications of existing and emerging microfluidic platforms for blood analysis, and for diagnosis and monitoring of cancer and infectious disease. Together, this chapter should elucidate the potential that microfluidic systems have in the development of effective diagnostic technologies through a review of existing technologies and promising directions.

iTRAQ-based proteomics reveals SOD2 as a potential salivary biomarker in liver cancer

BACKGROUND

Salivary proteomic analysis has been extensively used in a wide range of cancer, but not in hepatocellular carcinoma. The aim of this study was to identify potential salivary biomarkers for hepatocellular carcinoma clinical screening.

METHODS

In this study, we performed isobaric tags for relative and absolute quantitation (iTRAQ)-based quantitative proteomics analysis to detect differentially expressed proteins between saliva samples from 15 hepatocellular carcinoma patients and 15 healthy controls. Enzyme-linked immunosorbent assay (ELISA) verification was undertaken in saliva samples from 14 hepatocellular carcinoma patients and 14 healthy controls.

RESULTS

Overall, 133 proteins with significant differential expression level (ratio > 1.5 or < 0.67) were detected. Using bioinformatic analysis, two candidate proteins were selected and subsequently verified by ELISA. The increased expression of superoxide dismutase 2, mitochondrial (SOD2) in hepatocellular carcinoma patients was confirmed by ELISA, with an area under the curve value of 0.9082.

CONCLUSIONS

iTRAQ-based quantitative proteomics revealed that SOD2 might serve as a potential salivary biomarker for hepatocellular carcinoma detection. Our results indicated that a noninvasive and inexpensive salivary test might be established for hepatocellular carcinoma detection.

Metabolomics Analysis in Serum from Patients with Colorectal Polyp and Colorectal Cancer by 1H-NMR Spectrometry

Colorectal cancer (CRC) is one of the leading causes of cancer-related death worldwide. Colorectal adenomatous polyps are at high risk for the development of CRC. In this report, we described the metabolic changes in the sera from patients with colorectal polyps and CRC by using the NMR-based metabolomics. 110 serum samples were collected from patients and healthy controls, including 40 CRC patients, 32 colorectal polyp patients, and 38 healthy controls. The metabolic profiles and differential metabolites of sera were analyzed by multivariate statistical analysis (MSA), including principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA) methods. A total of 23 differential metabolites were identified from MSA. According to the pathway analysis and multivariate ROC curve-based exploratory analysis by using the relative concentrations of differential metabolites, we found abnormal metabolic pathways and potential biomarkers involved with the colorectal polyp and CRC. The results showed that the pyruvate metabolism and glycerolipid metabolism were activated in colorectal polyps. And the glycolysis and glycine, serine, and threonine metabolism were activated in CRC. The changed metabolism may promote cellular proliferation. In addition, we found that the rates of acetate/glycerol and lactate/citrate could be the potential biomarkers in colorectal polyp and CRC, respectively. The application of ¹H-NMR metabolomics analysis in serum has interesting potential as a new detection and diagnostic tool for early diagnosis of CRC.

Pushing the limits of electrochemistry toward challenging applications in clinical diagnosis, prognosis, and therapeutic action

Constant progress in the identification of biomarkers at different molecular levels in samples of different natures, and the need to conduct routine analyses, even in limited-resource settings involving simple and short protocols, are examples of the growing current clinical demands not satisfied by conventional available techniques. In this context, the unique features offered by electrochemical biosensors, including affordability, real-time and reagentless monitoring, simple handling and portability, and versatility, make them especially interesting for adaptation to the increasingly challenging requirements of current clinical and point-of-care (POC) diagnostics. This has allowed the continuous development of strategies with improved performance in the clinical field that were unthinkable just a few years ago. After a brief introduction to the types and characteristics of clinically relevant biomarkers/samples, requirements for their analysis, and currently available methodologies, this review article provides a critical discussion of the most important developments and relevant applications involving electrochemical biosensors reported in the last five years in response to the demands of current diagnostic, prognostic, and therapeutic actions related to high prevalence and high mortality diseases and disorders. Special attention is paid to the rational design of surface chemistry and the use/modification of state-of-the-art nanomaterials to construct electrochemical bioscaffolds with antifouling properties that can be applied to the single or multiplex determination of biomarkers of accepted or emerging clinical relevance in particularly complex clinical samples, such as undiluted liquid biopsies, whole cells, and paraffin-embedded tissues, which have scarcely been explored using conventional techniques or electrochemical biosensing. Key points guiding future development, challenges to be addressed to further push the limits of electrochemical biosensors towards new challenging applications, and their introduction to the market are also discussed.

Bioassay of saliva proteins: The best alternative for conventional methods in non-invasive diagnosis of cancer

Non-invasive diagnosis of cancer is often the key to effective treatment and patient survival. Saliva as a multi-constituent oral fluid comprises various disease signaling biomarkers, holds great potential for early-stage cancer diagnostics with cost-effective and easy collection, storage, transport and processing. Therefore, detection of biomarkers and proteins in the saliva samples is highly demand. The current review was performed using reliable internet database (mainly PubMed) to provide an overview of the most recent developments on non-invasive diagnosis of cancers in saliva and highlights main challenges and future prospects in sensing of the salivary biomarkers. The conventional detection methods of cancer biomarkers in saliva is discussed in the paper, however, the main focus is on non-invasive diagnosis of cancers in saliva using immunosensing (electrochemical, optical, piezoelectric), DNA based sensors, aptasensors and peptide based bio-assays The reviewed literature revealed that non-invasive cancer detection methods using the mentioned biosensors and without any processing of saliva sample offers a quick, sensitive, specific and cost effective analytical tool. Besides, salivary based detection methods can be used for simultaneous detection of panels of disease specific biomarkers in a real time manner or as home testing kits in near future.

Electrochemically deposited silver detection substrate for surface-enhanced Raman spectroscopy cancer diagnostics

Surface-enhanced Raman spectroscopy (SERS) of blood plasma on an electrochemically prepared silver surface has been studied as a label-free, noninvasive diagnostic test for colorectal cancer. Indium tin oxide glass substrates were modified with 0.01  mol dm  -  3 silver nitrate using the pulsed double-potentiostatic method. The prepared silver substrates were tested with Rhodamine 6G as a model analyte and the surface with the highest signal enhancement was selected. This silver dendritic surface was used as a diagnostic substrate for SERS measurements of human blood plasma. A group of oncological patients with declared colorectal carcinoma (n  =  15) and the control group of healthy volunteers (n  =  15) were compared. The biomolecular changes in chemical composition in the cancer samples were detected by statistical processing of the resulting SERS spectra. About 94% specificity and 100% sensitivity were achieved for the analysis by the ratio of the SERS peak intensity at 725  cm  -  1 for adenine to the peak intensity at 638  cm  -  1 for tyrosine and 100% specificity and sensitivity by using principal component analysis. This method of SERS diagnostics of colorectal cancer, which does not require the nanoparticle preparation, mixing, and incubation of plasma with a colloidal solution as in conventional tests, is a rapid, inexpensive method, which could be introduced as a primary diagnostic test.

Wireless, intraoral hybrid electronics for real-time quantification of sodium intake toward hypertension management

Recent wearable devices offer portable monitoring of biopotentials, heart rate, or physical activity, allowing for active management of human health and wellness. Such systems can be inserted in the oral cavity for measuring food intake in regard to controlling eating behavior, directly related to diseases such as hypertension, diabetes, and obesity. However, existing devices using plastic circuit boards and rigid sensors are not ideal for oral insertion. A user-comfortable system for the oral cavity requires an ultrathin, low-profile, and soft electronic platform along with miniaturized sensors. Here, we introduce a stretchable hybrid electronic system that has an exceptionally small form factor, enabling a long-range wireless monitoring of sodium intake. Computational study of flexible mechanics and soft materials provides fundamental aspects of key design factors for a tissue-friendly configuration, incorporating a stretchable circuit and sensor. Analytical calculation and experimental study enables reliable wireless circuitry that accommodates dynamic mechanical stress. Systematic in vitro modeling characterizes the functionality of a sodium sensor in the electronics. In vivo demonstration with human subjects captures the device feasibility for real-time quantification of sodium intake, which can be used to manage hypertension.

Implementing liquid biopsies into clinical decision making for cancer immunotherapy

During the last decade, novel immunotherapeutic strategies, in particular antibodies directed against immune checkpoint inhibitors, have revolutionized the treatment of different malignancies leading to an improved survival of patients. Identification of immune-related biomarkers for diagnosis, prognosis, monitoring of immune responses and selection of patients for specific cancer immunotherapies is urgently required and therefore areas of intensive research. Easily accessible samples in particular liquid biopsies (body fluids), such as blood, saliva or urine, are preferred for serial tumor biopsies.

Although monitoring of immune and tumor responses prior, during and post immunotherapy has led to significant advances of patients’ outcome, valid and stable prognostic biomarkers are still missing. This might be due to the limited capacity of the technologies employed, reproducibility of results as well as assay stability and validation of results. Therefore solid approaches to assess immune regulation and modulation as well as to follow up the nature of the tumor in liquid biopsies are urgently required to discover valuable and relevant biomarkers including sample preparation, timing of the collection and the type of liquid samples. This article summarizes our knowledge of the well-known liquid material in a new context as liquid biopsy and focuses on collection and assay requirements for the analysis and the technical developments that allow the implementation of different high-throughput assays to detect alterations at the genetic and immunologic level, which could be used for monitoring treatment efficiency, acquired therapy resistance mechanisms and the prognostic value of the liquid biopsies.

Human salivary microRNAs in Cancer

Circulating microRNAs (miRNAs) have emerged as excellent candidates for cancer biomarkers. Several recent studies have highlighted the potential use of saliva for the identification of miRNAs as novel biomarkers, which represents a great opportunity to improve diagnosis and monitor general health and disease. This review summarises the mechanisms of miRNAs deregulation in cancer, the value of targeting them with a therapeutic intention and the evidence of the potential clinical use of miRNAs expressed in saliva for the detection of different cancer types. We also provide a comprehensive review of the different methods for normalising the levels of specific miRNAs present in saliva, as this is a critical step in their analysis, and the challenge to validate salivary miRNAs as a reality to manage cancer patients.

Synergistic Use of Gold Nanoparticles (AuNPs) and "Capillary Enzyme-Linked Immunosorbent Assay (ELISA)" for High Sensitivity and Fast Assays

Using gold nanoparticles (AuNPs) on "capillary enzyme-linked immunosorbent assay (ELISA)", we produced highly sensitive and rapid assays, which are the major attributes for point-of-care applications. First, in order to understand the size effect of AuNPs, AuNPs of varying diameters (5 nm, 10 nm, 15 nm, 20 nm, 30 nm, and 50 nm) conjugated with Horseradish Peroxidase (HRP)-labeled anti-C reactive protein (antiCRP) (AuNP•antiCRP-HRP) were used for well-plate ELISA. AuNP of 10 nm produced the largest optical density, enabling detection of 0.1 ng/mL of CRP with only 30 s of incubation, in contrast to 10 ng/mL for the ELISA run in the absence of AuNP. Then, AuNP of 10 nm conjugated with antiCRP-HRP (AuNP•antiCRP-HRP) was used for "capillary ELISA" to detect as low as 0.1 ng/mL of CRP. Also, kinetic study on both 96-well plates and in a capillary tube using antiCRP-HRP or AuNP•antiCRP-HRP showed a synergistic effect between AuNP and the capillary system, in which the fastest assay was observed from the "AuNP capillary ELISA", with its maximum absorbance reaching 2.5 min, while the slowest was the typical well-plate ELISA with its maximum absorbance reaching in 13.5 min.

Salivary Diagnostics in Pediatrics: Applicability, Translatability, and Limitations

In the last decade, technological advances, combined with an improved appreciation of the ability of saliva to inform caregivers about both oral health and systemic disease, have led to the emergence of salivary diagnostic platforms. However, the majority of these assays have targeted diseases that more commonly affect the adult population, largely neglecting infants and children who arguably could benefit the most from non-invasive assessment tools for health monitoring. Gaining access into development, infection, and disease through comprehensive "omic" analyses of saliva could significantly improve care and enhance health access. In this review, we will highlight novel applications of salivary diagnostics in pediatrics across the "omic" spectrum, including at the genomic, transcriptomic, proteomic, microbiomic, and metabolomic level. The challenges to implementing salivary platforms into care, including the effects of age, diet, and developmental stage on salivary components, will be reviewed. Ultimately, large-scale, multicenter trials must be performed to establish normative biomarker values across the age spectrum to accurately discriminate between health and disease. Only then can salivary diagnostics truly translate into pediatric care.

The oral cavity microbiota: between health, oral disease, and cancers of the aerodigestive tract

Many studies show that the human microbiome plays a critical role in the chronic pathologies of obesity, inflammatory bowel diseases, and diabetes. More recently, the interaction between cancer and the microbiome has been highlighted. Most studies have focused on the gut microbiota because it represents the most extensive bacterial community, and the body of evidence correlating it with gut syndromes is increasing. However, in the strict sense, the gastrointestinal (GI) tract begins in the oral cavity, and special attention should be paid to the specific flora of this cavity. This study reviewed the current knowledge about the various microbial ecosystems of the upper part of the GI tract and discussed their potential link to carcinogenesis. The overall composition of the microbial communities, as well as the presence or absence of "key species", in relation to carcinogenesis is addressed. Alterations in the oral microbiota can potentially be used to predict the risk of cancer. Molecular advances and the further monitoring of the microbiota will increase our understanding of the role of the microbiota in carcinogenesis and open new perspectives for future therapeutic and prophylactic modalities.

Emerging technologies for salivaomics in cancer detection

Salivary diagnostics has great potential to be used in the early detection and prevention of many cancerous diseases. If implemented with rigour and efficiency, it can result in improving patient survival times and achieving earlier diagnosis of disease. Recently, extraordinary efforts have been taken to develop non‐invasive technologies that can be applied without complicated and expensive procedures. Saliva is a biofluid that has demonstrated excellent properties and can be used as a diagnostic fluid, since many of the biomarkers suggested for cancers can also be found in whole saliva, apart from blood or other body fluids. The currently accepted gold standard methods for biomarker development include chromatography, mass spectometry, gel electrophoresis, microarrays and polymerase chain reaction‐based quantification. However, salivary diagnostics is a flourishing field with the rapid development of novel technologies associated with point‐of‐care diagnostics, RNA sequencing, electrochemical detection and liquid biopsy. Those technologies will help introduce population‐based screening programs, thus enabling early detection, prognosis assessment and disease monitoring. The purpose of this review is to give a comprehensive update on the emerging diagnostic technologies and tools for the early detection of cancerous diseases based on saliva.

Silver-functionalized g-C3N4 nanohybrids as signal-transduction tags for electrochemical immunoassay of human carbohydrate antigen 19-9

A simple and feasible electrochemical immunosensing platform was developed for highly efficient screening of a disease-related protein (human carbohydrate antigen 19-9, CA 19-9 used in this case) using silver-functionalized g-C3N4 nanosheets (Ag/g-C3N4) as signal-transduction tags. Initially, Ag/g-C3N4 nanohybrids were synthesized by combining thermal polymerization of the melamine precursor with the photo-assisted reduction method. Thereafter, the as-synthesized Ag/g-C3N4 nanohybrids were utilized for the labeling of the anti-CA 19-9 detection antibody by using a typical carbodiimide coupling method. The assay was carried out on a capture antibody-modified glassy carbon electrode in a sandwich-type detection mode. The detectable signal mainly derived from the voltammetric characteristics of the immobilized nanosilver particles on the g-C3N4 nanosheets within the applied potentials. Under the optimal conditions, the voltammetric peak currents increased with the increasing amount of target CA 19-9, and exhibited a wide linear range from 5.0 mU mL(-1) to 50 U mL(-1) with a detection limit of 1.2 mU mL(-1). Our strategy also displayed good reproducibility, precision and specificity. The results of the analysis of clinical serum specimens were in good accordance with the results obtained by an enzyme-linked immunosorbent assay (ELISA) method. The newly developed immunosensing system is promising for enzyme-free and cost-effective analysis of low-abundance proteins.