Smartphone surface plasmon resonance imaging for the simultaneous and sensitive detection of acute kidney injury biomarkers with noninvasive urinalysis

Surface plasmon resonance biosensors and their medical applications

Surface plasmon resonance (SPR) biosensors are an advanced optical biosensing technology that has been widely used in molecular biology for the investigation of biomolecular interactions and in bioanalytics for the detection of biological species. This work aims to review progress in the development of SPR biosensors for medical diagnostics, focusing mainly on advances in optical platforms and assays enabling analysis of complex biological matrices. Applications of SPR biosensors for the detection of medically relevant analytes, such as nucleic acids, proteins, exosomes, viruses, bacteria, and circulating tumor cells, are also reviewed. The detection performance of current SPR biosensors is discussed, and routes for improving performance and expanding applications of SPR biosensors in medical diagnostics are outlined.

Quantum-dot-spectrometer-based virtual barcode for the sensitive colorimetric urinalysis

Colorimetric sensing methods are extensively utilized for rapid and sensitive detection of various biomedical and environmental targets, with higher dimensional spectra resulting in more accurate results. Miniature reconstructive spectrometers, as portable colorimetric sensing devices, show promise in capturing high-dimension spectra signals, while facing the challenges of noise-sensitive spectrum reconstruction and complex pre-calibration. To address these issues, we present a virtual barcode method, which is directly based on the utilization of a high-dimension quantum dot (QD) spectrometer intensity vector. Any spectral changes of the analytes can be reflected in the corresponding barcode, without the redundant operation for spectral analysis. We demonstrate the QD barcode method in quantitatively detecting multiple biomarkers in the artificial human urine, including urinary calcium, glucose, nitrite, and creatinine, with lower limits of detection compared to the RGB sensing method (2.4-14.4-fold). To simplify the preparation of the QD spectrometer, we optimize both the number and the spectral distribution of QD filters. Furthermore, an artificial neural network model is also established to achieve 8-fold improved quantitative recognition performance. This QD barcode method can greatly broadens the biosensing application of miniaturized reconstructive spectrometers.

Fast response cathodic electrochemiluminescence sensor based on closed bipolar electrode for point-of-care blood glucose testing

Glucose detection is vital for managing diabetes, monitoring metabolic disorders, and developing advanced biosensors. Electrochemical methods are widely used for glucose detection due to their sensitivity, portability, and low cost. However, these methods also have several limitations, such as interference from non-specific molecules, fouling of electrodes, and enzyme stability. Herein, to avoid external interference, we report a fast response cathodic electrochemiluminescence (ECL) glucose biosensor using a closed bipolar electrode (BPE) system with two separate cells (reporting cell and sensing cell). In this platform, Tris(2,2'-bipyridyl) ruthenium and K2S2O8 were used as the luminophore and co-reagent, respectively, to generate the cathodic ECL in the reporting cell, and a commercial test strip modified with GOx (glucose oxidase) and mediator served as the BPE anode to detect glucose in the sensing cell. The developed technique was able to determine glucose with a good correlation in the quantification of glucose in human serum samples with a fast response under a low potential, which avoided side reactions and was comparable to the commercial blood glucose meter. In addition, the sensing mechanism and working principle have been thoroughly studied, with the detailed discussion of the effect of oxygen and acetonitrile in influencing the ECL generation. Using this platform, glucose in the buffer was successfully quantified up to 18 mM, achieving a limit of detection of 3.8 mM and a linear concentration range between 4 and 12 mM. This electrochemical technique offers a simple and cost-effective strategy for point-of-care blood glucose testing without external interference, thereby opening up emerging opportunities in a broad range of sensing applications.

Smartphones as a platform for molecular analysis: concepts, methods, devices and future potential

Over the past 15 years, smartphones have had a transformative effect on everyday life. These devices also have the potential to transform molecular analysis over the next 15 years. The cameras of a smartphone, and its many additional onboard features, support optical detection and other aspects of engineering an analytical device. This article reviews the development of smartphones as platforms for portable chemical and biological analysis. It is equal parts conceptual overview, technical tutorial, critical summary of the state of the art, and outlook on how to advance smartphones as a tool for analysis. It further discusses the motivations for adopting smartphones as a portable platform, summarizes their enabling features and relevant optical detection methods, then highlights complementary technologies and materials such as 3D printing, microfluidics, optoelectronics, microelectronics, and nanoparticles. The broad scope of research and key advances from the past 7 years are reviewed as a prelude to a perspective on the challenges and opportunities for translating smartphone-based lab-on-a-chip devices from prototypes to authentic applications in health, food and water safety, environmental monitoring, and beyond. The convergence of smartphones with smart assays and smart apps powered by machine learning and artificial intelligence holds immense promise for realizing a future for molecular analysis that is powerful, versatile, democratized, and no longer just the stuff of science fiction.

Engineered Nanoparticles for Theranostic Applications in Kidney Repair

Kidney diseases are characterized by their intricate nature and complexity, posing significant challenges in their treatment and diagnosis. Nanoparticles (NPs), which can be further classified as synthetic and biomimetic NPs, have emerged as promising candidates for treating various diseases. In recent years, the development of engineered nanotherapeutics has focused on targeting damaged tissues and serving as drug delivery vehicles. Additionally, these NPs have shown superior sensitivity and specificity in diagnosis and imaging, thus providing valuable insights for the early detection of diseases. This review aims to focus on the application of engineered synthetic and biomimetic NPs in kidney diseases in the aspects of treatment, diagnosis, and imaging. Notably, the current perspectives and challenges are evaluated, which provide inspiration for future research directions, and encourage the clinical application of NPs in this field.

Simultaneous Detection of Biomarkers in Urine Using a Multicalibration Potentiometric Sensing Array Combined with a Portable Analyzer

Domestic monitoring devices make real-time and long-term health monitoring possible, allowing people to track their health status regularly. Uric acid (UA), creatinine, and urea in urine are three important biomarkers for various diseases, especially kidney diseases. This work proposed a 10-channel potentiometric sensing array containing a UA electrode group, a creatinine electrode group, a urea electrode group, a pH electrode group, and one pair of reference channels, which could be connected with a portable potentiometric analyzer, realizing the simultaneous detection of UA, creatinine, urea, and pH in urine. The prepared Pt/carbon nanotubes (CNTs)-uricase, creatinine deiminase, Au@urease, and polyaniline were employed as the sensing materials, showing responses to four targets with high sensitivity and selectivity. To improve the accuracy of domestic monitoring, a calibration channel was integrated into each electrode group to calibrate the basic potential of the sensing channels, and the influences of pH and temperature on the responses were investigated through the pH electrode group and an external temperature probe to calibrate the slope and intercept. With the preset of the deduced calibration parameters and computational formula for the four targets in the analyzer in Lab Mode, the concentrations of UA, creatinine, and urea and the pH of the human urine samples were directly displayed on the screen of the analyzer in Practical Mode. The agreement of these results with those obtained from commercial kits and pH meters reveals the high potential of these methods for developing domestic devices to facilitate health monitoring.

Recent advancements of smartphone-based sensing technology for diagnosis, food safety analysis, and environmental monitoring

The emergence of computationally powerful smartphones, relatively affordable high-resolution camera, drones, and robotic sensors have ushered in a new age of advanced sensible monitoring tools. The present review article investigates the burgeoning smartphone-based sensing paradigms, including surface plasmon resonance (SPR) biosensors, electrochemical biosensors, colorimetric biosensors, and other innovations for modern healthcare. Despite the significant advancements, there are still scarcity of commercially available smart biosensors and hence need to accelerate the rates of technology transfer, application, and user acceptability. The application/necessity of smartphone-based biosensors for Point of Care (POC) testing, such as prognosis, self-diagnosis, monitoring, and treatment selection, have brought remarkable innovations which eventually eliminate sample transportation, sample processing time, and result in rapid findings. Additionally, it articulates recent advances in various smartphone-based multiplexed bio sensors as affordable and portable sensing platforms for point-of-care devices, together with statistics for point-of-care health monitoring and their prospective commercial viability.

Carbon-Based Fluorescent Nano-Biosensors for the Detection of Cell-Free Circulating MicroRNAs

Currently, non-communicable diseases (NCDs) have emerged as potential risks for humans due to adopting a sedentary lifestyle and inaccurate diagnoses. The early detection of NCDs using point-of-care technologies significantly decreases the burden and will be poised to transform clinical intervention and healthcare provision. An imbalance in the levels of circulating cell-free microRNAs (ccf-miRNA) has manifested in NCDs, which are passively released into the bloodstream or actively produced from cells, improving the efficacy of disease screening and providing enormous sensing potential. The effective sensing of ccf-miRNA continues to be a significant technical challenge, even though sophisticated equipment is needed to analyze readouts and expression patterns. Nanomaterials have come to light as a potential solution as they provide significant advantages over other widely used diagnostic techniques to measure miRNAs. Particularly, CNDs-based fluorescence nano-biosensors are of great interest. Owing to the excellent fluorescence characteristics of CNDs, developing such sensors for ccf-microRNAs has been much more accessible. Here, we have critically examined recent advancements in fluorescence-based CNDs biosensors, including tools and techniques used for manufacturing these biosensors. Green synthesis methods for scaling up high-quality, fluorescent CNDs from a natural source are discussed. The various surface modifications that help attach biomolecules to CNDs utilizing covalent conjugation techniques for multiple applications, including self-assembly, sensing, and imaging, are analyzed. The current review will be of particular interest to researchers interested in fluorescence-based biosensors, materials chemistry, nanomedicine, and related fields, as we focus on CNDs-based nano-biosensors for ccf-miRNAs detection applications in the medical field.