Optical Biosensors for Therapeutic Drug Monitoring

Advanced aptamer-based sensors for monitoring theophylline

Theophylline is a widely used bronchodilator for treating asthma-related symptoms like shortness of breath and chest tightness. However, its narrow therapeutic plasma range (20-200 μM) necessitates careful monitoring of blood levels to prevent toxicity. Various clinical laboratory techniques have been developed for detecting theophylline, including spectroscopy, high-performance liquid chromatography (HPLC), fluorescence polarization immunoassay, and radioimmunoassay. Despite their utility, these methods are limited by complex sample preparation, long processing times, large sample volumes, and high costs. Aptamer-based biosensors have emerged as a promising alternative, offering superior selectivity and specificity compared to conventional methods. This review evaluates the performance of aptamer-based sensors in terms of sensitivity, specificity, and limit of detection, comparing them to traditional techniques. Recent studies demonstrate the advantages of aptamer-based sensors, including their simplicity, rapid response time, and cost-effectiveness, which make them ideal for point-of-care applications. The review also explores the methodologies used in aptamer-based detection, highlighting key innovations and advances in the field. Findings from the literature show how aptamer-based sensors enhance the monitoring of theophylline levels, overcoming the limitations of traditional techniques. This is the first review dedicated to discussing aptamer-based techniques for theophylline monitoring, addressing a gap in current literature.

Unlocking new frontiers in healthcare: The impact of nano-optical biosensors on personalized medical diagnostics

Nano-optical biosensors have emerged as transformative tools in healthcare and clinical research, offering rapid, portable, and specific diagnostic solutions. This review critically analyzes the recent advancements, translational challenges, and sustainable approaches in nano-optical biosensor implementation for biomedical applications. We explore the integration of innovative nanomaterials, microelectronics, and molecular biology techniques that have significantly enhanced biosensor sensitivity and specificity, enabling detection of biomarkers ranging from cancer indicators to cardiovascular markers. The potential of nanoplasmonic and silicon photonic biosensors in overcoming current limitations is discussed, alongside the promising integration of artificial intelligence and Internet of Things technologies for improved data analytics and clinical validation. We address key challenges, including size constraints, energy efficiency, and integration with existing technologies, and propose sustainable strategies for eco-friendly materials, energy-efficient designs, and circular economy approaches. The review also examines emerging trends such as multiplexed sensing platforms, wearable biosensors, and their applications in personalized medicine. By critically assessing these developments, we provide insights into the prospects of nano-optical biosensors and their potential to revolutionize point-of-care diagnostics and personalized healthcare, while emphasizing the need for interdisciplinary collaboration to overcome remaining obstacles in translating these technologies from laboratory research to real-world clinical applications.

Analysis of Personalized Cardiovascular Drug Therapy: From Monitoring Technologies to Data Integration and Future Perspectives

Cardiovascular diseases have long been a major challenge to human health, and the treatment differences caused by individual variability remain unresolved. In recent years, personalized cardiovascular drug therapy has attracted widespread attention. This paper reviews the strategies for achieving personalized cardiovascular drug therapy through traditional dynamic monitoring and multidimensional data integration and analysis. It focuses on key technologies for dynamic monitoring, dynamic monitoring based on individual differences, and multidimensional data integration and analysis. By systematically reviewing the relevant literature, the main challenges in current research and the proposed potential directions for future studies were summarized.

Silicon-Based Biosensors: A Critical Review of Silicon's Role in Enhancing Biosensing Performance

This review into recent advancements in silicon-based technology, with a particular emphasis on the biomedical applications of silicon sensors. Owing to their diminutive size, high sensitivity, and intrinsic compatibility with electronic systems, silicon-based sensors have found widespread utilization across healthcare, industrial, and environmental monitoring domains. In the realm of biomedical sensing, silicon has demonstrated significant potential to enhance human health outcomes while simultaneously driving progress in microfabrication techniques for multifunctional device development. The review systematically examines the versatile roles of silicon in the fabrication of electrodes, sensing channels, and substrates. Silicon electrodes are widely used in electrochemical biosensors for glucose monitoring and neural activity recording, while sensing channels in field-effect transistor biosensors enable the detection of cancer biomarkers and small molecules. Porous silicon substrates are applied in optical biosensors for label-free protein and pathogen detection. Key challenges in this field, including the interaction of silicon with biomolecules, the economic barriers to miniaturization, and issues related to signal stability, are critically analyzed. Proposed strategies to address these challenges and improve sensor functionality and reliability are also discussed. Furthermore, the article explores emerging developments in silicon-based biosensors, particularly their integration into wearable technologies. The pivotal role of artificial intelligence (AI) in enhancing the performance, functionality, and real-time capabilities of these sensors is also highlighted. This review provides a comprehensive overview of the current state, challenges, and future directions in the field of silicon-based biomedical sensing technologies.

Towards Point-of-Care Single Biomolecule Detection Using Next Generation Portable Nanoplasmonic Biosensors: A Review

Over the past few years, nanoplasmonic biosensors have gained widespread interest for early diagnosis of diseases thanks to their simple design, low detection limit down to the biomolecule level, high sensitivity to even small molecules, cost-effectiveness, and potential for miniaturization, to name but a few benefits. These intrinsic natures of the technology make it the perfect solution for compact and portable designs that combine sampling, analysis, and measurement into a miniaturized chip. This review summarizes applications, theoretical modeling, and research on portable nanoplasmonic biosensor designs. In order to develop portable designs, three basic components have been miniaturized: light sources, plasmonic chips, and photodetectors. There are five types of portable designs: portable SPR, miniaturized components, flexible, wearable SERS-based, and microfluidic. The latter design also reduces diffusion times and allows small amounts of samples to be delivered near plasmonic chips. The properties of nanomaterials and nanostructures are also discussed, which have improved biosensor performance metrics. Researchers have also made progress in improving the reproducibility of these biosensors, which is a major obstacle to their commercialization. Furthermore, future trends will focus on enhancing performance metrics, optimizing biorecognition, addressing practical constraints, considering surface chemistry, and employing emerging technologies. In the foreseeable future, these trends will be merged to result in portable nanoplasmonic biosensors offering detection of even a single biomolecule.

Photonic and electrochemical biosensors for near-patient tests-a critical comparison

Research into diagnostic biosensors is a vibrant field that combines scientific challenge with translational opportunities; innovation in healthcare is of great societal interest and is an essential element of future healthcare provision. Photonic and electrochemical biosensors are the dominant modalities, both scientifically and commercially, yet the two scientific communities largely remain separated and siloed. It seems astute to better understand what the two fields can learn from one another so as to progress the key scientific, translational, and commercial challenges. Here, we provide an analysis of the fundamental operational characteristics of photonic and electrochemical biosensors using a classification based on energy transfer; in photonics, this separates refractive index sensors from fluorescence and vibrational spectroscopy, while in electrochemistry, it distinguishes Faradaic from non-Faradaic processes. This classification allows us to understand some of the key performance characteristics, such as the susceptibility to fouling and dependence on the clinical matrix that is being analyzed. We discuss the use of labels and the ultimate performance limits, and some of the unique advantages of photonics, such as multicolor operation and fingerprinting, and critically evaluate the requirements for translation of these technologies for clinical use. We trust that this critical review will inform future research in biosensors and support both scientific and commercial developments.

Recent advances in surface plasmon resonance for the detection of ovarian cancer biomarkers: a thorough review

Early detection of ovarian cancer (OC) is crucial for effective management and treatment, as well as reducing mortality rates. However, the current diagnostic methods for OC are time-consuming and have low accuracy. Surface plasmon resonance (SPR) biosensors offer a promising alternative to conventional techniques, as they enable rapid and less invasive screening of various circulating indicators. These biosensors are widely used for biomolecular interaction analysis and detecting tumor markers, and they are currently being investigated as a rapid diagnostic tool for early-stage cancer detection. Our main focus is on the fundamental concepts and performance characteristics of SPR biosensors. We also discuss the latest advancements in SPR biosensors that enhance their sensitivity and enable high-throughput quantification of OC biomarkers, including CA125, HE4, CEA, and CA19-9. Finally, we address the future challenges that need to be overcome to advance SPR biosensors from research to clinical applications. The ultimate goal is to facilitate the translation of SPR biosensors into routine clinical practice for the early detection and management of OC.

Innovations in Biosensor Technologies for Healthcare Diagnostics and Therapeutic Drug Monitoring: Applications, Recent Progress, and Future Research Challenges

This comprehensive review delves into the forefront of biosensor technologies and their critical roles in disease biomarker detection and therapeutic drug monitoring. It provides an in-depth analysis of various biosensor types and applications, including enzymatic sensors, immunosensors, and DNA sensors, elucidating their mechanisms and specific healthcare applications. The review highlights recent innovations such as integrating nanotechnology, developing wearable devices, and trends in miniaturisation, showcasing their transformative potential in healthcare. In addition, it addresses significant sensitivity, specificity, reproducibility, and data security challenges, proposing strategic solutions to overcome these obstacles. It is envisaged that it will inform strategic decision-making, drive technological innovation, and enhance global healthcare outcomes by synthesising multidisciplinary insights.

Advances in heart failure monitoring: Biosensors targeting molecular markers in peripheral bio-fluids

Cardiovascular diseases (CVDs), especially chronic heart failure, threaten many patients' lives worldwide. Because of its slow course and complex causes, its clinical screening, diagnosis, and prognosis are essential challenges. Clinical biomarkers and biosensor technologies can rapidly screen and diagnose. Multiple types of biomarkers are employed for screening purposes, precise diagnosis, and treatment follow-up. This article provides an up-to-date overview of the biomarkers associated with the six main heart failure etiology pathways. Plasma natriuretic peptides (BNP and NT-proBNP) and cardiac troponins (cTnT, cTnl) are still analyzed as gold-standard markers for heart failure. Other complementary biomarkers include growth differentiation factor 15 (GDF-15), circulating Galactose Lectin 3 (Gal-3), soluble interleukin (sST2), C-reactive protein (CRP), and tumor necrosis factor-alpha (TNF-α). For these biomarkers, the electrochemical biosensors have exhibited sufficient sensitivity, detection limit, and specificity. This review systematically summarizes the latest molecular biomarkers and sensors for heart failure, which will provide comprehensive and cutting-edge authoritative scientific information for biomedical and electronic-sensing researchers in the field of heart failure, as well as patients. In addition, our proposed future outlook may provide new research ideas for researchers.

New Insights into Aptamers: An Alternative to Antibodies in the Detection of Molecular Biomarkers

Aptamers are short oligonucleotides with single-stranded regions or peptides that recently started to transform the field of diagnostics. Their unique ability to bind to specific target molecules with high affinity and specificity is at least comparable to many traditional biorecognition elements. Aptamers are synthetically produced, with a compact size that facilitates deeper tissue penetration and improved cellular targeting. Furthermore, they can be easily modified with various labels or functional groups, tailoring them for diverse applications. Even more uniquely, aptamers can be regenerated after use, making aptasensors a cost-effective and sustainable alternative compared to disposable biosensors. This review delves into the inherent properties of aptamers that make them advantageous in established diagnostic methods. Furthermore, we will examine some of the limitations of aptamers, such as the need to engage in bioinformatics procedures in order to understand the relationship between the structure of the aptamer and its binding abilities. The objective is to develop a targeted design for specific targets. We analyse the process of aptamer selection and design by exploring the current landscape of aptamer utilisation across various industries. Here, we illuminate the potential advantages and applications of aptamers in a range of diagnostic techniques, with a specific focus on quartz crystal microbalance (QCM) aptasensors and their integration into the well-established ELISA method. This review serves as a comprehensive resource, summarising the latest knowledge and applications of aptamers, particularly highlighting their potential to revolutionise diagnostic approaches.

Photonic Nanochains for Continuous Glucose Monitoring in Physiological Environment

Diabetes is a common disease that seriously endangers human health. Continuous glucose monitoring (CGM) is important for the prevention and treatment of diabetes. Glucose-sensing photonic nanochains (PNCs) have the advantages of naked-eye colorimetric readouts, short response time and noninvasive detection of diabetes, showing immense potential in CGM systems. However, the developed PNCs cannot disperse in physiological environment at the pH of 7.4 because of their poor hydrophilicity. In this study, we report a new kind of PNCs that can continuously and reversibly detect the concentration of glucose (Cg) in physiological environment at the pH of 7.4. Polyacrylic acid (PAA) added to the preparation of PNCs forms hydrogen bonds with polyvinylpyrrolidone (PVP) in Fe3O4@PVP colloidal nanoparticles and the hydrophilic monomer N-2-hydroxyethyl acrylamide (HEAAm), which increases the content of PHEAAm in the polymer shell of prepared PNCs. Moreover, 4-(2-acrylamidoethylcarbamoyl)-3-fluorophenylboronic acid (AFPBA), with a relatively low pKa value, is used as the glucose-sensing monomer to further improve the hydrophilicity and glucose-sensing performances of PNCs. The obtained Fe3O4@(PVP-PAA)@poly(AFPBA-co-HEAAm) PNCs disperse in artificial serum and change color from yellow-green to red when Cg increases from 3.9 mM to 11.4 mM, showing application potential for straightforward CGM.

Micro/nanofluidic device for tamsulosin therapeutic drug monitoring in patients with benign prostatic hyperplasia at point of care

Discovering the balance between toxicity and efficacy for many drugs requires therapeutic drug monitoring (TDM) of their concentrations in the blood. Here, a hot-embossed microfluidic device with a new design integrated to a nanofracture is presented for purification of blood samples from numerous proteins and cells, allowing to the separation of small molecules from blood matrix. The device was used to separate and quantitatively detect tamsulosin drug after derivatization with fluorescamine reagent, allowing converting it from a neutral molecule into a charged fluorescent complex under the experimental conditions, and thus its separation by electrophoresis. The device is portable and easy operated, and the presented method showed good linearity (R2 = 0.9948) over a concentration range of 0.1-1 μg/mL. The relative standard deviation (RSD%) was below 10% (n = 3), indicating good precisions, and the limit of detection (LOD) and limit of quantitation (LOQ) values were estimated to be 0.1 and 0.55 μg/mL, respectively. Whole blood samples from 10 patients with benign prostatic hyperplasia (BPH) were analyzed, showing good percentage recoveries of tamsulosin in whole blood. This point-of-care (POC), low-cost method could increase the convenience of patients and doctors, make therapies safer, and make TDM available in different regions and places.

Graphene-integrated microring cavity for electronically controlled molecular fingerprinting

Microring cavities supporting whispering-gallery modes (WGMs) have an exceptionally high quality factor (Q) and a small mode volume, greatly improving the interaction between light and matter, which has attracted great attention in various microscale/nanoscale photonic devices and potential applications. Recently, two-dimensional van der Waals (vdW) materials such as graphene have emerged as a potential platform for next-generation biosensing by enabling the confinement of light fields at the nanoscale. Here, we propose what we believe to be a novel approach to achieve molecular fingerprint retrieval by integrating graphene into a microring cavity and conducting numerical simulations using the finite-difference time-domain (FDTD) method. The hybrid cavity exhibits high-quality WGMs with a high Q factor of up to 800. Moreover, the resonant wavelength can be electronically controlled through modulation of graphene's Fermi level, enabling coverage of the entire free spectral range at infrared frequencies. By depositing a thin layer of biomolecular material (e.g., CBP) onto the surface of our hybrid cavity, we are able to accurately read out the absorption spectrum at multiple spectral points, thereby achieving broadband fingerprint retrieval for the targeted biomolecule. Our results pave the way for highly sensitive, chip-integrated, miniaturized, and electrically modulated infrared spectroscopy biosensing.

Emerging therapeutic drug monitoring technologies: considerations and opportunities in precision medicine

In recent years, the development of sensor and wearable technologies have led to their increased adoption in clinical and health monitoring settings. One area that is in early, but promising, stages of development is the use of biosensors for therapeutic drug monitoring (TDM). Traditionally, TDM could only be performed in certified laboratories and was used in specific scenarios to optimize drug dosage based on measurement of plasma/blood drug concentrations. Although TDM has been typically pursued in settings involving medications that are challenging to manage, the basic approach is useful for characterizing drug activity. TDM is based on the idea that there is likely a clear relationship between plasma/blood drug concentration (or concentration in other matrices) and clinical efficacy. However, these relationships may vary across individuals and may be affected by genetic factors, comorbidities, lifestyle, and diet. TDM technologies will be valuable for enabling precision medicine strategies to determine the clinical efficacy of drugs in individuals, as well as optimizing personalized dosing, especially since therapeutic windows may vary inter-individually. In this mini-review, we discuss emerging TDM technologies and their applications, and factors that influence TDM including drug interactions, polypharmacy, and supplement use. We also discuss how using TDM within single subject (N-of-1) and aggregated N-of-1 clinical trial designs provides opportunities to better capture drug response and activity at the individual level. Individualized TDM solutions have the potential to help optimize treatment selection and dosing regimens so that the right drug and right dose may be matched to the right person and in the right context.

Overview of therapeutic drug monitoring and clinical practice

With the rapid development of clinical pharmacy in China, therapeutic drug monitoring (TDM) has become an essential tool for guiding rational clinical drug use and is widely concerned. TDM is a tool that combines pharmacokinetic and pharmacodynamic knowledge to optimize personalized drug therapy, which can improve treatment outcomes, reduce drug-drug toxicity, and avoid the risk of developing drug resistance. To effectively implement TDM, accurate and sophisticated analytical methods are required. By researching the literature published in recent years, we summarize the types of commonly monitored drugs, therapeutic windows, and clinical assays and track the trends and hot spots of therapeutic drug monitoring. The purpose is to provide guidelines for clinical blood drug concentration monitoring, to implement individualized drug delivery programs better, to ensure the rational use of drugs for patients, and to provide a reference for the group to carry out related topics in the future.

Aptasensors: employing molecular probes for precise medical diagnostics and drug monitoring

Accurate detection and monitoring of therapeutic drug levels are vital for effective patient care and treatment management. Aptamers, composed of single-stranded DNA or RNA molecules, are integral components of biosensors designed for both qualitative and quantitative detection of biological samples. Aptasensors play crucial roles in target identification, validation, detection of drug-target interactions and screening potential of drug candidates. This review focuses on the pivotal role of aptasensors in early disease detection, particularly in identifying biomarkers associated with various diseases such as cancer, infectious diseases and cardiovascular disorders. Aptasensors have demonstrated exceptional potential in enhancing disease diagnostics and monitoring therapeutic drug levels. Aptamer-based biosensors represent a transformative technology in the field of healthcare, enabling precise diagnostics, drug monitoring and disease detection.

Paper-Based Analytical Device Based on Potentiometric Transduction for Sensitive Determination of Phenobarbital

In medicine, barbiturates are a class of depressive medications used as hypnotics, anticonvulsants, and anxiolytics. For the treatment of specific forms of epilepsy and seizures in young children in underdeveloped countries, the World Health Organization recommends phenobarbital (PBAR), a barbiturate drug. This review describes the fabrication and characterization of a paper-based analytical apparatus for phenobarbital detection that is straightforward, affordable, portable, and disposable. All of the solid-state ion-selective electrodes (ISEs) for PBAR as well as a Ag/AgCl reference electrode were constructed and optimized on a nonconductive paper substrate. Using carbon nanotube ink, the sensors were made to function as an ion-to-electron transducer and to make the paper conductive. A suitable polymeric membrane is drop-cast onto the surface of the carbon ink orifice. The pyrido-tetrapeptide and pyrido-hexapeptide derivatives, which were recently synthesized, functioned as distinct ionophores in the PBAR-membrane sensor, enabling its detection. With a detection limit of 5.0 × 10-7 M, the manufactured analytical device demonstrated a Nernstian response to PBAR anions in 50 mM phosphate buffer, pH 8.5, over a linear range of 1.0 × 10-6 to 1.0 × 10-3 M. The PBAR-based sensors showed quick (less than 5 s) response times for PBAR ion detection. The modified separate solution method was utilized to evaluate the selectivity pattern of these novel ionophores with respect to PBAR ions in comparison to other common anions. The analytical instrument that was exhibited on paper had good precision both within and between days. The suggested technology assisted in the detection of trace amounts of PBAR in real pharmaceutical samples. A comparison was made between the data acquired using the HPLC reference method and the information obtained by the recommended potentiometric approach. The described paper-based analytical device may be a good choice for point-of-care PBAR determination because it is cheap and easy to find and can self-pump (especially when combined with potentiometric detection).

A novel strategy for therapeutic drug monitoring: application of biosensors to quantify antimicrobials in biological matrices

Over the past few years, therapeutic drug monitoring (TDM) has gained practical significance in antimicrobial precision therapy. Yet two categories of mainstream TDM techniques (chromatographic analysis and immunoassays) that are widely adopted nowadays retain certain inherent limitations. The use of biosensors, an innovative strategy for rapid evaluation of antimicrobial concentrations in biological samples, enables the implementation of point-of-care testing (POCT) and continuous monitoring, which may circumvent the constraints of conventional TDM and provide strong technological support for individualized antimicrobial treatment. This comprehensive review summarizes the investigations that have harnessed biosensors to detect antimicrobial drugs in biological matrices, provides insights into the performance and characteristics of each sensing form, and explores the feasibility of translating them into clinical practice. Furthermore, the future trends and obstacles to achieving POCT and continuous monitoring are discussed. More efforts are necessary to address the four key 'appropriateness' challenges to deploy biosensors in clinical practice, paving the way for personalized antimicrobial stewardship.

A review of current effective COVID-19 testing methods and quality control

COVID-19 is a highly infectious disease caused by the SARS-CoV-2 virus, which primarily affects the respiratory system and can lead to severe illness. The virus is extremely contagious, early and accurate diagnosis of SARS-CoV-2 is crucial to contain its spread, to provide prompt treatment, and to prevent complications. Currently, the reverse transcriptase polymerase chain reaction (RT-PCR) is considered to be the gold standard for detecting COVID-19 in its early stages. In addition, loop-mediated isothermal amplification (LMAP), clustering rule interval short palindromic repeats (CRISPR), colloidal gold immunochromatographic assay (GICA), computed tomography (CT), and electrochemical sensors are also common tests. However, these different methods vary greatly in terms of their detection efficiency, specificity, accuracy, sensitivity, cost, and throughput. Besides, most of the current detection methods are conducted in central hospitals and laboratories, which is a great challenge for remote and underdeveloped areas. Therefore, it is essential to review the advantages and disadvantages of different COVID-19 detection methods, as well as the technology that can enhance detection efficiency and improve detection quality in greater details.

Determination of Tyrosine Kinase Inhibitors via Capillary Electrophoresis with Tandem Mass Spectrometry and Online Stacking Preconcentration

Capillary electrophoresis connected with tandem mass spectrometry was employed for the development of a method for determination of various tyrosine kinase inhibitors in plasma samples. A stacking online preconcentration with a 120 cm-long capillary was used for the determination of bosutinib, dasatinib, canertinib, and erlotinib at physiologically relevant concentrations. The optimization included both capillary electrophoresis and mass spectrometry steps. Under optimal conditions, 50 mM formic acid pH 2.5, an injection time of 120 s, and an optimized mass spectrometry set-up (as sheath liquid composition 75:24.9:0.1 (v/v) methanol, water, formic acid, and appropriate conditions for ion transitions), LODs in a range of 3.9-23.0 nmol·L-1 were observed. The method was validated in terms of linearity, limit of detection, limit of quantification, repeatability of migration times and peak area, and recovery using plasma as a matrix for analytes. The results showed that this method has great promise for use in many analytical tasks, e.g., therapeutic drug monitoring.

Emerging nanophotonic biosensor technologies for virus detection

Highly infectious viral diseases are a serious threat to mankind as they can spread rapidly among the community, possibly even leading to the loss of many lives. Early diagnosis of a viral disease not only increases the chance of quick recovery, but also helps prevent the spread of infections. There is thus an urgent need for accurate, ultrasensitive, rapid, and affordable diagnostic techniques to test large volumes of the population to track and thereby control the spread of viral diseases, as evidenced during the COVID-19 and other viral pandemics. This review paper critically and comprehensively reviews various emerging nanophotonic biosensor mechanisms and biosensor technologies for virus detection, with a particular focus on detection of the SARS-CoV-2 (COVID-19) virus. The photonic biosensing mechanisms and technologies that we have focused on include: (a) plasmonic field enhancement via localized surface plasmon resonances, (b) surface enhanced Raman scattering, (c) nano-Fourier transform infrared (nano-FTIR) near-field spectroscopy, (d) fiber Bragg gratings, and (e) microresonators (whispering gallery modes), with a particular emphasis on the emerging impact of nanomaterials and two-dimensional materials in these photonic sensing technologies. This review also discusses several quantitative issues related to optical sensing with these biosensing and transduction techniques, notably quantitative factors that affect the limit of detection (LoD), sensitivity, specificity, and response times of the above optical biosensing diagnostic technologies for virus detection. We also review and analyze future prospects of cost-effective, lab-on-a-chip virus sensing solutions that promise ultrahigh sensitivities, rapid detection speeds, and mass manufacturability.

Fluorescence-polarization immunoassays within glass fiber micro-chambers enable tobramycin quantification in whole blood for therapeutic drug monitoring at the point of care

Many therapeutic drugs require monitoring of their concentration in blood followed by dose adjustments in order to ensure efficacy while minimizing adverse effects. It would be highly desirable to perform such measurements rapidly and with reduced sample volumes to support point-of-care testing. Here, we demonstrate that the concentration of small therapeutics can be determined in whole blood within paper-like membranes using Fluorescence Polarization Immunoassay (FPIA). Different types of paper-like materials such as glass microfibers, cellulose and filter paper were investigated for artefacts such as scattering or autofluorescence. Accurate determination of the fluorescence polarization of red-emitting fluorophores at sub-nanomolar concentrations was feasible within glass fiber membranes. This enabled the development of a competitive immunoassay for the quantification of the antibiotic tobramycin using only 1 μL of plasma in glass fiber micro-chambers. Furthermore, the same membrane was used for transversal separation of blood cells followed by accurate FPIA read-out at the bottom part of the micro-chamber. For quantification of tobramycin, 1 μL of whole blood was incubated with the immunoassay reagents during only 3 min before deposition in the micro-chamber and analysis. Within the therapeutic window, coefficients of variation were around 20% and recoveries between 80 and 105%. Owing to the simplified procedure requiring no centrifugation, the reduced blood sample volume and the rapid analysis time, we envision that this novel method supports the performance of therapeutic drug monitoring directly at the point of care.

Surface Plasmon Resonance (SPR) Spectroscopy and Photonic Integrated Circuit (PIC) Biosensors: A Comparative Review

Label-free direct-optical biosensors such as surface-plasmon resonance (SPR) spectroscopy has become a gold standard in biochemical analytics in centralized laboratories. Biosensors based on photonic integrated circuits (PIC) are based on the same physical sensing mechanism: evanescent field sensing. PIC-based biosensors can play an important role in healthcare, especially for point-of-care diagnostics, if challenges for a transfer from research laboratory to industrial applications can be overcome. Research is at this threshold, which presents a great opportunity for innovative on-site analyses in the health and environmental sectors. A deeper understanding of the innovative PIC technology is possible by comparing it with the well-established SPR spectroscopy. In this work, we shortly introduce both technologies and reveal similarities and differences. Further, we review some latest advances and compare both technologies in terms of surface functionalization and sensor performance.

Recent advances in the potential applications of luminescence-based, SPR-based, and carbon-based biosensors

Abstract

The need for biosensors has evolved in the detection of molecules, diseases, and pollution from various sources. This requirement has headed to the development of accurate and powerful equipment for analysis using biological sensing component as a biosensor. Biosensors have the advantage of rapid detection that can beat the conventional methods for the detection of the same molecules. Bio-chemiluminescence-based sensors are very sensitive during use in biological immune assay systems. Optical biosensors are emerging with time as they have the advantage that they act with a change in the refractive index. Carbon nanotube-based sensors are another area that has an important role in the biosensor field. Bioluminescence gives much higher quantum yields than classical chemiluminescence. Electro-generated bioluminescence has the advantage of miniature size and can produce a high signal-to-noise ratio and the controlled emission. Recent advances in biological techniques and instrumentation involving fluorescence tag to nanomaterials have increased the sensitivity limit of biosensors. Integrated approaches provided a better perspective for developing specific and sensitive biosensors with high regenerative potentials. This paper mainly focuses on sensors that are important for the detection of multiple molecules related to clinical and environmental applications.

Key points

• The review focusses on the applications of luminescence-based, surface plasmon resonance-based, carbon nanotube-based, and graphene-based biosensors

• Potential clinical, environmental, agricultural, and food industry applications/uses of biosensors have been critically reviewed

• The current limitations in this field are discussed, as well as the prospects for future advancement

Therapeutic Drug Monitoring as a Tool for Therapy Optimization

The use of pharmacotherapy for improving healthcare in society is increasing. A vast majority of patients have either received subtherapeutic treatment (which could result from low pharmacokinetic) or experienced adverse effects due to the toxic levels of the drug. The medicines used to treat chronic conditions, such as epilepsy; cardiovascular diseases; and oncological, neurological, and psychiatric disorders, require routine monitoring. New targeted therapies suggest an individualized treatment that can slowly move practitioners away from the concept of a one-size-fits-all-fixed-dosing approach. Therapeutic drug use can be monitored based on pharmacokinetic, pharmacodynamic, and pharmacometric methods. Based on the experiences of therapeutic drug monitoring of various agents across the globe, we can look ahead to the possible developments of therapeutic drug monitoring in India.

An integrated device for fast and sensitive immunosuppressant detection

The present paper describes a compact point of care (POC) optical device for therapeutic drug monitoring (TDM). The core of the device is a disposable plastic chip where an immunoassay for the determination of immunosuppressants takes place. The chip is designed in order to have ten parallel microchannels allowing the simultaneous detection of more than one analyte with replicate measurements. The device is equipped with a microfluidic system, which provides sample mixing with the necessary chemicals and pumping samples, reagents and buffers into the measurement chip, and with integrated thin film amorphous silicon photodiodes for the fluorescence detection. Submicrometric fluorescent magnetic particles are used as support in the immunoassay in order to improve the efficiency of the assay. In particular, the magnetic feature is used to concentrate the antibody onto the sensing layer leading to a much faster implementation of the assay, while the fluorescent feature is used to increase the optical signal leading to a larger optical dynamic change and consequently a better sensitivity and a lower limit of detection. The design and development of the whole integrated optical device are here illustrated. In addition, detection of mycophenolic acid and cyclosporine A in spiked solutions and in microdialysate samples from patient blood with the implemented device are reported.

Therapeutic Drug Monitoring of Antibiotics in Critically Ill Patients: Current Practice and Future Perspectives With a Focus on Clinical Outcome

PURPOSE

Early initiation of antibiotics is essential for ameliorating infections in critically ill patients. The correct dosage of antibiotics is imperative to ensure their adequate exposure. Critically ill patients have altered pharmacokinetic parameters and are often infected by less susceptible microorganisms. Differences in drug disposition are not considered with standard doses of antibiotics. This can lead to suboptimal antibiotic exposure in critically ill patients. To overcome this problem of suboptimal dosing, therapeutic drug monitoring (TDM) is a strategy commonly used to support individualized dosing of antibiotics. It is routinely used for vancomycin and aminoglycosides in clinical practice. In recent years, it has become apparent that TDM may also be used in other antibiotics.

METHODS

This review summarizes the evidence for TDM of antibiotics in critically ill patients, focuses on clinical outcomes, and summarizes possibilities for optimized TDM in the future.

RESULTS AND CONCLUSION

After reviewing the literature, we can conclude that general TDM implementation is advised for glycopeptides and aminoglycosides, as evidence of the relationship between TDM and clinical outcome is present. For antibiotics, such as beta-lactams, fluoroquinolones, and linezolid, it seems rational to perform TDM in specific patient cases. TDM involving other antibiotics is supported by individual cases, specifically to decrease toxicity. When focusing on future possibilities to improve TDM of antibiotics in critically ill patients, implementation of model-informed precision dosing should be investigated because it can potentially streamline the TDM process. The logistics of TDM, such as turnaround time and available equipment, are challenging but may be overcome by rapid bioanalytical techniques or real-time monitoring of drug concentrations through biosensors in the future. Education, clinical information on targets, and clinical outcome studies are other important factors that facilitate TDM implementation.

A Methodical Review on the Applications and Potentialities of Using Nanobiosensors for Disease Diagnosis

Presently, with the introduction of nanotechnology, the evolutions and applications of biosensors and/or nanobiosensors are becoming prevalent in various scientific domains such as environmental and agricultural sciences as well as biomedical, clinical, and healthcare sciences. Trends in these aspects have led to the discovery of various biosensors/nanobiosensors with their tremendous benefits to mankind. The characteristics of the various biosensors/nanobiosensors are primarily based on the nature of nanomaterials/nanoparticles employed in the sensing mechanisms. In the last few years, the identification, as well as the detection of biological markers linked with any form of diseases (communicable or noncommunicable), has been accomplished by several sensing procedures using nanotechnology vis-à-vis biosensors/nanobiosensors. Hence, this study employs a systematic approach in reviewing some contemporary developed exceedingly sensitive nanobiosensors alongside their biomedical, clinical, or/and healthcare applications as well as their potentialities, specifically for the detection of some deadly diseases drawn from some of the recent publications. Ways forward in the form of future trends that will advance creative innovations of the potentialities of nanobiosensors for biomedical, clinical, or/and healthcare applications particularly for disease diagnosis are also highlighted.

New Age Detection of Viruses: The Nano-Biosensors

Viruses and their related diseases have always posed a significant hazard to humans. The current pandemic caused by the Covid-19 (SARS-CoV-2) virus is the latest illustration of what this tiny organism can do to humanity at large, putting everything on the brink of collapse. So it is reasonable that early diagnosis of infection from viruses remains a crucial step to prevent such human suffering. Many traditional methods are already in use for detecting viruses, including molecular approaches, serological methods, direct virus culture methods, and so on. Such traditional methods though are brilliant at some stages but are not devoid of drawbacks. To overcome the limits of conventional procedures, new techniques have been developed which tried to eradicate the demerits of the former procedures. Biosensors have come up with a lot of promises in terms of detecting viruses and diseases connected with them. The development of various types of such biosensors such as Affinity-based nano-biosensors, Nanoisland affinity-based biosensors, Graphene affinity-based biosensors, Nanowires based biosensors, Optical nano biosensors, Fiber optic nano-biosensors, Surface Plasmon Resonance (SPR) based optical nano-biosensors, Total internal reflection fluorescence, Surface-Enhanced Raman Scattering (SERS), Electrochemical nano-biosensors had helped us in the rapid and sensitive detection of viruses. Aid to these nanosensors, viral detection now becomes very sensitive, rapid and cost has come down to a significant low. In this review, an attempt has been made to compile all of the different nano-biosensors and their applications. Due attention is given to the fact that the reader gets the grasp of the concept with much ease.

Highly sensitive and quantitative biodetection with lipid-polymer hybrid nanoparticles having organic room-temperature phosphorescence

A versatile organic room-temperature phosphorescence (RTP)-based "turn on" biosensor platform has been devised with high sensitivity by combining oxygen-sensitive lipid-polymer hybrid RTP nanoparticles with a signal-amplifying enzymatic oxygen scavenging reaction in aqueous solutions. When integrated with a sandwich-DNA hybridization assay on 96-well plates, our phosphorimetric sensor demonstrates sequence-specific detection of a cell-free cancer biomarker, a TP53 gene fragment, with a sub-picomolar (0.5 p.m.) detection limit. This assay is compatible with detecting cell-free nucleic acids in human urine samples. Simply by re-programming the detection probe, our unique methodology can be adapted to a broad range of biosensor applications for biomarkers of great clinical importance but difficult to detect due to their low abundance in vivo.

On-Site Biolayer Interferometry-Based Biosensing of Carbamazepine in Whole Blood of Epileptic Patients

On-site monitoring of carbamazepine (CBZ) that allows rapid, sensitive, automatic, and high-throughput detection directly from whole blood is of urgent demand in current clinical practice for precision medicine. Herein, we developed two types (being indirect vs. direct) of fiber-optic biolayer interferometry (FO-BLI) biosensors for on-site CBZ monitoring. The indirect FO-BLI biosensor preincubated samples with monoclonal antibodies towards CBZ (MA-CBZ), and the mixture competes with immobilized CBZ to bind towards MA-CBZ. The direct FO-BLI biosensor used sample CBZ and CBZ-horseradish peroxidase (CBZ-HRP) conjugate to directly compete for binding with immobilized MA-CBZ, followed by a metal precipitate 3,3'-diaminobenzidine to amplify the signals. Indirect FO-BLI detected CBZ within its therapeutic range and was regenerated up to 12 times with negligible baseline drift, but reported results in 25 min. However, Direct FO-BLI achieved CBZ detection in approximately 7.5 min, down to as low as 10 ng/mL, with good accuracy, specificity and negligible matric interference using a high-salt buffer. Validation of Direct FO-BLI using six paired sera and whole blood from epileptic patients showed excellent agreement with ultra-performance liquid chromatography. Being automated and able to achieve high throughput, Direct FO-BLI proved itself to be more effective for integration into the clinic by delivering CBZ values from whole blood within minutes.

BioChemPen for a Rapid Analysis of Compounds Supported on Solid Surfaces

We present BioChemPen, a portable wireless biosensor device for rapid analysis of substances adsorbed on solid surfaces. The device takes advantage of (bio)luminescent reactions taking place in a hydrogel matrix. In a typical embodiment, the active element of this device is a hydrogel disk (chemotransducer) containing enzyme(s), electrolyte solution, and all of the necessary substrates. When the hydrogel is exposed to a solid sample surface containing the target analyte, light is produced. A photoresistor (phototransducer), placed in close proximity to the hydrogel disk, detects the light. The operation of the BioChemPen is enabled by a MicroPython PyBoard microcontroller board and other low-cost electronic modules. The obtained results are immediately uploaded to the Internet cloud. In one application, we demonstrate an analysis of hypochlorite-containing cleaning agents present on the surfaces of daily use objects by an assay based on hydrogel embedded with luminol and hydrogen peroxide. In another application, we use hydrogel embedded with luciferin, luciferase, and pyruvate kinase to detect adenosine triphosphate (ATP), and adenosine diphosphate (ADP), and link the ATP content with meat freshness. Lastly, we demonstrate the detection of organophosphate pesticides present on vegetables with the hydrogel containing acetylcholinesterase, choline oxidase, and horseradish peroxidase. The limits of detection for sodium hypochlorite, ATP, ADP, and chlorpyrifos-methyl (a pesticide) were 7.95 × 10^-11, 2.73 × 10^-13, 2.35 × 10^-12, and 2.59 × 10^-10 mol mm^-2, respectively.

Nanomaterials-Based Sensors for Respiratory Viral Detection: A Review

Contagious diseases are the principal cause of mortality, particularly respiratory viruses, a real menace for public health and economic development worldwide. Therefore, timely diagnosis and treatments are the only life-saving strategy to overcome any epidemic and particularly the ongoing prevailing pandemic COVID-19 caused by SARS-CoV-2. A rapid identification, point of care, portable, highly sensitive, stable, and inexpensive device is needed which is exceptionally satisfied by sensor technology. Consequently, the researchers have directed their attention to employing sensors targeting multiple analyses of pathogenic detections across the world. Nanostructured materials (nanoparticles, nanowires, nanobundles, etc.), owing to their unique characteristics such as large surface-to-volume ratio and nanoscale interactions, are widely employed to fabricate facile sensors to meet all the immediate emerging challenges and threats. This review is anticipated to foster researchers in developing advanced nanomaterials-based sensors for the increasing number of COVID-19 cases across the globe. The mechanism of respiratory viral detection by nanomaterials-based sensors has been reported. Moreover, the advantages, disadvantages, and their comparison with conventional sensors are summarized. Furthermore, we have highlighted the challenges and future potential of these sensors for achieving efficient and rapid detection.

The Effect of Plasma Protein Binding on the Therapeutic Monitoring of Antiseizure Medications

Epilepsy is a widely diffused neurological disorder including a heterogeneous range of syndromes with different aetiology, severity and prognosis. Pharmacological treatments are based on the use, either in mono- or in polytherapy, of antiseizure medications (ASMs), which act at different synaptic levels, generally modifying the excitatory and/or inhibitory response through different action mechanisms. To reduce the risk of adverse effects and drug interactions, ASMs levels should be closely evaluated in biological fluids performing an appropriate Therapeutic Drug Monitoring (TDM). However, many decisions in TDM are based on the determination of the total drug concentration although measurement of the free fraction, which is not bound to plasma proteins, is becoming of ever-increasing importance since it correlates better with pharmacological and toxicological effects. Aim of this work has been to review methodological aspects concerning the evaluation of the free plasmatic fraction of some ASMs, focusing on the effect and the clinical significance that drug-protein binding has in the case of widely used drugs such as valproic acid, phenytoin, perampanel and carbamazepine. Although several validated methodologies are currently available which are effective in separating and quantifying the different forms of a drug, prospective validation studies are undoubtedly needed to better correlate, in real-world clinical contexts, pharmacokinetic monitoring to clinical outcomes.

Tunable Van der Waal's optical metasurfaces (VOMs) for biosensing of multiple analytes

Van der Waal's heterostructure assembling low dimensional materials are the new paradigm in the field of nanophotonics. In this work, we theoretically investigate Van der Waal's optical metasurfaces consisting of graphene and hBN for the application of biosensing of multiple analytes in the mid-infrared (MIR) region. Phonon polaritons of hexagonal boron nitride (hBN) show an advantage over plasmon polaritons, as the phonon polaritons are lossless and possess high momentum and enhanced lifetime. The hybrid phonon mode produced at 6.78 µm in the mid-infrared (MIR) region with near-perfect absorption is used for surface-enhanced infrared absorption (SEIRA) based detection of organic analytes. Moreover, by adding the graphene layer, the device's overall resonance responses can be tuned, enabling it to identify multiple organic analytes-such as 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) and nitrobenzene (Nb) [C₆H₅NO₂], just by changing graphene's fermi potential (Ef). Owing to large wave vector of phonon polariton, the device has the capability to detect small amount of number of molecules (390 for CBP and 1990 for nitrobenzene), thus creating a highly sensitive optical biosensor.

Recent Advances in Enzymatic and Non-Enzymatic Electrochemical Glucose Sensing

The detection of glucose is crucial in the management of diabetes and other medical conditions but also crucial in a wide range of industries such as food and beverages. The development of glucose sensors in the past century has allowed diabetic patients to effectively manage their disease and has saved lives. First-generation glucose sensors have considerable limitations in sensitivity and selectivity which has spurred the development of more advanced approaches for both the medical and industrial sectors. The wide range of application areas has resulted in a range of materials and fabrication techniques to produce novel glucose sensors that have higher sensitivity and selectivity, lower cost, and are simpler to use. A major focus has been on the development of enzymatic electrochemical sensors, typically using glucose oxidase. However, non-enzymatic approaches using direct electrochemistry of glucose on noble metals are now a viable approach in glucose biosensor design. This review discusses the mechanisms of electrochemical glucose sensing with a focus on the different generations of enzymatic-based sensors, their recent advances, and provides an overview of the next generation of non-enzymatic sensors. Advancements in manufacturing techniques and materials are key in propelling the field of glucose sensing, however, significant limitations remain which are highlighted in this review and requires addressing to obtain a more stable, sensitive, selective, cost efficient, and real-time glucose sensor.

Optical biosensors - Illuminating the path to personalized drug dosing

Optical biosensors are low-cost, sensitive and portable devices that are poised to revolutionize the medical industry. Healthcare monitoring has already been transformed by such devices, with notable recent applications including heart rate monitoring in smartwatches and COVID-19 lateral flow diagnostic test kits. The commercial success and impact of existing optical sensors has galvanized research in expanding its application in numerous disciplines. Drug detection and monitoring seeks to benefit from the fast-approaching wave of optical biosensors, with diverse applications ranging from illicit drug testing, clinical trials, monitoring in advanced drug delivery systems and personalized drug dosing. The latter has the potential to significantly improve patients' lives by minimizing toxicity and maximizing efficacy. To achieve this, the patient's serum drug levels must be frequently measured. Yet, the current method of obtaining such information, namely therapeutic drug monitoring (TDM), is not routinely practiced as it is invasive, expensive, time-consuming and skilled labor-intensive. Certainly, optical sensors possess the capabilities to challenge this convention. This review explores the current state of optical biosensors in personalized dosing with special emphasis on TDM, and provides an appraisal on recent strategies. The strengths and challenges of optical biosensors are critically evaluated, before concluding with perspectives on the future direction of these sensors.

Biosensors for the detection of respiratory viruses: A review

The recent events of outbreaks related to different respiratory viruses in the past few years, exponentiated by the pandemic caused by the coronavirus disease 2019 (COVID-19), reported worldwide caused by SARS-CoV-2, raised a concern and increased the search for more information on viruses-based diseases. The detection of the virus with high specificity and sensitivity plays an important role for an accurate diagnosis. Despite the many efforts to identify the SARS-CoV-2, the diagnosis still relays on expensive and time-consuming analysis. A fast and reliable alternative is the use of low-cost biosensor for in loco detection. This review gathers important contributions in the biosensor area regarding the most current respiratory viruses, presents the advances in the assembly of the devices and figures of merit. All information is useful for further biosensor development for the detection of respiratory viruses, such as for the new coronavirus.

Clinical Applications of Visual Plasmonic Colorimetric Sensing

Colorimetric analysis has become of great importance in recent years to improve the operationalization of plasmonic-based biosensors. The unique properties of nanomaterials have enabled the development of a variety of plasmonics applications on the basis of the colorimetric sensing provided by metal nanoparticles. In particular, the extinction of localized surface plasmon resonance (LSPR) in the visible range has permitted the exploitation of LSPR colorimetric-based biosensors as powerful tools for clinical diagnostics and drug monitoring. This review summarizes recent progress in the biochemical monitoring of clinical biomarkers by ultrasensitive plasmonic colorimetric strategies according to the distance- or the morphology/size-dependent sensing modes. The potential of colorimetric nanosensors as point of care devices from the perspective of naked-eye detection is comprehensively discussed for a broad range of analytes including pharmaceuticals, proteins, carbohydrates, nucleic acids, bacteria, and viruses such as Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The practical suitability of plasmonic-based colorimetric assays for the rapid visual readout in biological samples, considering current challenges and future perspectives, is also reviewed.

Aptamer-Based Detection of Ampicillin in Urine Samples

The misuse of antibiotics in health care has led to increasing levels of drug resistant infections (DRI's) occurring in the general population. Most technologies developed for the detection of DRI's typically focus on phenotyping or genotyping bacterial resistance rather than on the underlying cause and spread of DRI's; namely the misuse of antibiotics. An aptameric based assay has been developed for the monitoring of ampicillin in urine samples, for use in determining optimal antibiotic dosage and monitoring patient compliance with treatment. The fluorescently labelled aptamers were shown to perform optimally at pH 7, ideal for buffered clinical urine samples, with limits of detection as low as 20.6 nM, allowing for determination of ampicillin in urine in the clinically relevant range of concentrations (100 nM to 100 µM). As the assay requires incubation for only 1 h with a small sample volume, 50 to 150 µL, the test would fit within current healthcare pathways, simplifying the adoption of the technology.

Pinacho D. Personalized Medicine for Antibiotics: The Role of Nanobiosensors in Therapeutic Drug Monitoring

Due to the high bacterial resistance to antibiotics (AB), it has become necessary to adjust the dose aimed at personalized medicine by means of therapeutic drug monitoring (TDM). TDM is a fundamental tool for measuring the concentration of drugs that have a limited or highly toxic dose in different body fluids, such as blood, plasma, serum, and urine, among others. Using different techniques that allow for the pharmacokinetic (PK) and pharmacodynamic (PD) analysis of the drug, TDM can reduce the risks inherent in treatment. Among these techniques, nanotechnology focused on biosensors, which are relevant due to their versatility, sensitivity, specificity, and low cost. They provide results in real time, using an element for biological recognition coupled to a signal transducer. This review describes recent advances in the quantification of AB using biosensors with a focus on TDM as a fundamental aspect of personalized medicine.