Microsphere based continuous-flow immunoassay in a microfluidic device for determination of clinically relevant insulin levels

Cost-effective microfluidic flow cytometry for precise and gentle cell sorting

Microfluidic flow cytometry (MFCM) is considered to be an effective substitute for traditional flow cytometry, because of its advantages in terms of higher integration, smaller device size, lower cost, and higher cell sorting activity. However, MFCM still faces challenges in balancing parameters such as sorting throughput, viability, sorting efficiency, and cost. Here, we demonstrate a cost-effective and high-performance microfluidic cytometry cell sorting system, along with a customized microfluidic chip that integrates hydrodynamic focusing, droplet encapsulation, and sorting for precise cell manipulation. An innovative photon incremental counting-based fluorescence detection method is proposed, which requires only one-fiftieth of the data compared to traditional methods. This significantly simplifies the structure of the system and substantially reduces costs. The system exhibits detection recoveries exceeding 95% across sample solution flow rates ranging from 10 to 80 μL min-1. Moreover, it accurately achieves individual droplet deflections at a droplet generation frequency of 1600 Hz. Ultimately, our cell sorting system offers an impressive sorting efficiency of 90.7% and a high cell viability of 94.3% when operating at a droplet generation frequency of 1316 Hz, highlighting its accuracy and gentleness throughout the entire process. Our work will enhance advances in the life sciences, thereby creating a boom in great applications in single-cell cloning, single-cell analysis, drug screening, etc.

Microfluidic-based systems for the management of diabetes

Diabetes currently affects approximately 500 million people worldwide and is one of the most common causes of mortality in the United States. To diagnose and monitor diabetes, finger-prick blood glucose testing has long been used as the clinical gold standard. For diabetes treatment, insulin is typically delivered subcutaneously through cannula-based syringes, pens, or pumps in almost all type 1 diabetic (T1D) patients and some type 2 diabetic (T2D) patients. These painful, invasive approaches can cause non-adherence to glucose testing and insulin therapy. To address these problems, researchers have developed miniaturized blood glucose testing devices as well as microfluidic platforms for non-invasive glucose testing through other body fluids. In addition, glycated hemoglobin (HbA1c), insulin levels, and cellular biomechanics-related metrics have also been considered for microfluidic-based diabetes diagnosis. For the treatment of diabetes, insulin has been delivered transdermally through microdevices, mostly through microneedle array-based, minimally invasive injections. Researchers have also developed microfluidic platforms for oral, intraperitoneal, and inhalation-based delivery of insulin. For T2D patients, metformin, glucagon-like peptide 1 (GLP-1), and GLP-1 receptor agonists have also been delivered using microfluidic technologies. Thus far, clinical studies have been widely performed on microfluidic-based diabetes monitoring, especially glucose sensing, yet technologies for the delivery of insulin and other drugs to diabetic patients with microfluidics are still mostly in the preclinical stage. This article provides a concise review of the role of microfluidic devices in the diagnosis and monitoring of diabetes, as well as the delivery of pharmaceuticals to treat diabetes using microfluidic technologies in the recent literature.

Towards Point-of-Care Insulin Detection

Good glucose management through an insulin dose regime based on the metabolism of glucose helps millions of people worldwide manage their diabetes. Since Banting and Best extracted insulin, glucose management has improved due to the introduction of insulin analogues that act from 30 minutes to 28 days, improved insulin dose regimes, and portable glucose meters, with a current focus on alternative sampling sites that are less invasive. However, a piece of the puzzle is still missing-the ability to measure insulin directly in a Point-of-Care device. The ability to measure both glucose and insulin concurrently will enable better glucose control by providing an improved estimate for insulin sensitivity, minimizing variability in control, and maximizing safety from hypoglycaemia. However, direct detection of free insulin has provided a challenge due to the size of the molecule, the low concentration of insulin in blood, and the selectivity against interferants in blood. This review summarizes current insulin detection methods from immunoassays to analytical chemistry, and sensors. We also discuss the challenges and potential of each of the methods towards Point-of-Care insulin detection.