A nano-integrated microfluidic biochip for enzyme-based point-of-care detection of creatinine

Sensitive non-enzymatic sensing of creatinine in urine using a novel paper-based electroanalytical device

Accurate analysis of urinary creatinine levels is of great clinical significance. Non-enzymatic creatinine sensing systems (NECSs) have gained growing development because of higher stability and lower cost compared to enzymatic sensing systems. At present, there is a demand for simple approaches to develop NECSs with high sensitivity. In this study, we designed and fabricated an ingenious paper-based electroanalytical device for sensitive non-enzymatic creatinine sensing in urine. The device consisted of a paper-based chip and an integrated three-electrode system. The quantification of creatinine was performed based on the complexation of creatinine and copper sulfate (Cu2+), which was pre-stored on the paper-based chip in advance. Under optimum conditions, the detection limit of creatinine was 0.26 μM with a linear range of 1-5000 μM. The relative standard deviations of the electroanalytical results (n = 3) were within 1.2%-5.4%. The proposed device showed excellent reproducibility and stability, and the current response remained 92.17% of the initial response after a 30-day storage. Moreover, the device also exhibited high anti-interference ability to a variety of chemical components in urine. This study presents a simple and robust approach to engineering NECSs with high sensitivity. The preparation of the whole system is based on accessible and reliable commercial technologies and materials, which minimizes manual operation and ensures good reproducibility. The sensitivity of our method is two orders of magnitude lower than those of the previously reported NECSs based on the solution-modification strategy. It has been applied to the analysis of human urinary creatinine with satisfactory recoveries and without significant differences compared with commercial creatinine assay kits.

A DNA framework-based dual signal amplification biosensor for portable detection of SARS-CoV-2 and its mutations

We developed a rapid and accurate biosensor to detect SARS-CoV-2 and distinguish its mutations. Benefitting from a DNA framework-modified ordered interface and a dual signal amplification strategy, our biosensor could detect SARS-CoV-2 with a detection limit down to 10 fM. It performed well on pseudo virus and SARS-CoV-2 RNA standard materials, revealing the potential application in disease diagnosis and spread, in combination with a home-made smartphone.

Latest strategies for rapid and point of care detection of mycotoxins in food: A review

Mycotoxins contaminated in agricultural products are often highly carcinogenic and genotoxic to humans. With the streamlining of the food industry chain and the improvement of food safety requirements, the traditional laboratory testing mode is constantly challenged due to the expensive equipment, complex operation steps, and lag in testing results. Therefore, rapid detection methods are urgently needed in the food safety system. This review focuses on the latest strategies that can achieve rapid and on-site testing, with particular attention to the nanomaterials integrated biosensors. To provide researchers with the latest trends and inspiration in the field of rapid detection, we summarize several strategies suitable for point of care testing (POCT) of mycotoxins, including enzyme-linked immunoassay (ELISA), lateral flow assay (LFA), fluorescence, electrochemistry, and colorimetry assay. POCT-based strategies are all developing towards intelligence and portability, especially when combined with smartphones, making it easier to read signals for intuitive access and analysis of test data. Detection performance of the devices has also improved considerably with the integration of biosensors and nanomaterials.

Lab on a Chip Device for Diagnostic Evaluation and Management in Chronic Renal Disease: A Change Promoting Approach in the Patients' Follow Up

Lab-on-a-chip (LOC) systems are miniaturized devices aimed to perform one or several analyses, normally carried out in a laboratory setting, on a single chip. LOC systems have a wide application range, including diagnosis and clinical biochemistry. In a clinical setting, LOC systems can be associated with the Point-of-Care Testing (POCT) definition. POCT circumvents several steps in central laboratory testing, including specimen transportation and processing, resulting in a faster turnaround time. Provider access to rapid test results allows for prompt medical decision making, which can lead to improved patient outcomes, operational efficiencies, patient satisfaction, and even cost savings. These features are particularly attractive for healthcare settings dealing with complicated patients, such as those affected by chronic kidney disease (CKD). CKD is a pathological condition characterized by progressive and irreversible structural or functional kidney impairment lasting for more than three months. The disease displays an unavoidable tendency to progress to End Stage Renal Disease (ESRD), thus requiring renal replacement therapy, usually dialysis, and transplant. Cardiovascular disease (CVD) is the major cause of death in CKD, with a cardiovascular risk ten times higher in these patients than the rate observed in healthy subjects. The gradual decline of the kidney leads to the accumulation of uremic solutes, with negative effect on organs, especially on the cardiovascular system. The possibility to monitor CKD patients by using non-invasive and low-cost approaches could give advantages both to the patient outcome and sanitary costs. Despite their numerous advantages, POCT application in CKD management is not very common, even if a number of devices aimed at monitoring the CKD have been demonstrated worldwide at the lab scale by basic studies (low Technology Readiness Level, TRL). The reasons are related to both technological and clinical aspects. In this review, the main technologies for the design of LOCs are reported, as well as the available POCT devices for CKD monitoring, with a special focus on the most recent reliable applications in this field. Moreover, the current challenges in design and applications of LOCs in the clinical setting are briefly discussed.

Portable detection of multiple mycotoxins based on a sonic toothbrush, microfluidic chip and smartphone

A portable method for on-site detection of three mycotoxins was developed based on a sonic toothbrush, microfluidic chip and smartphone. Our method could complete all procedures, including sample pretreatment, signal conversion and processing, without any sophisticated instruments. The limits of detection for these mycotoxins were lower than the limit values in cereals in the standards of China and the European Union.

Microfluidic platforms integrated with nano-sensors for point-of-care bioanalysis

Microfluidic technology provides a portable, cost-effective, and versatile tool for point-of-care (POC) bioanalysis because of its associated advantages such as fast analysis, low volumes of reagent consumption, and high portability. Along with microfluidics, the application of nanomaterials in biosensing has attracted lots of attention due to their unique physical and chemical properties for enhanced signal modulation such as signal amplification and signal transduction for POC bioanalysis. Hence, an enormous number of microfluidic devices integrated with nano-sensors have been developed for POC bioanalysis targeting low-resource settings. Herein, we review recent advances in POC bioanalysis on nano-sensor-based microfluidic platforms. We first briefly summarized the different types of cost-effective microfluidic platforms, followed by a concise introduction to nanomaterial-based biosensors. Then, we highlighted the application of microfluidic platforms integrated with nano-sensors for POC bioanalysis. Finally, we discussed the current limitations and perspective trends of the nano-sensor-based microfluidic platforms for POC bioanalysis.

A Portable Biosensor Based on Au Nanoflower Interface Combined with Electrochemical Immunochromatography for POC Detection of Prostate-Specific Antigen

Serum prostate-specific antigen (PSA) is a widely used for the detection of prostate cancer and is considered the most reliable biomarker. However, the currently reported detection methods cannot achieve rapid monitoring. Here, we report a novel electrochemical immunochromatography (EIC) system for clinically accurate PSA detection. First, we constructed a carbon interface modified with gold nanoflowers (Au NFs) based on screen-printed carbon electrodes (SPCE), which acted as nanostructures with larger specific surface area that increased the number of PSA capture antibodies and can further improve detection signal-to-noise (S/N) ratio. Then, we fabricated detection chips by combining the SPCE/Au NFs with EIC. Under optimized conditions, the proposed biosensor exhibits high accuracy, taking only 15 minutes to complete detection. By measuring the levels of PSA in clinical blood samples, the biosensor can successfully discriminate clinically diagnosed prostate cancer patients from healthy controls.