The solubilization of lipid membranes by Tween-20 is crucial for a number of biotechnological applications, but the mechanistic details remain elusive. Evidence from ensemble assays supports a solubilization model that encompasses surfactant association with the membrane and the release of mixed micelles to solution, but whether this process also involves intermediate transitions between regimes is unanswered. In search of mechanistic origins, increasing focus is placed on identifying Tween-20 interactions with controllable membrane mimetics. Here, we employed ultrasensitive biosensing approaches, including single-vesicle spectroscopy based on fluorescence and energy transfer from membrane-encapsulated molecules, to interrogate interactions between Tween-20 and submicrometer-sized vesicles below the optical diffraction limit. We discovered that Tween-20, even at concentrations below the critical micellar concentration, triggers stepwise and phase-dependent structural remodeling events, including permeabilization and swelling, in both freely diffusing and surface-tethered vesicles, highlighting the substantial impact the surfactant has on vesicle conformation and stability prior to lysis.

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.

Antibiotic-functionalized gold nanoparticles able to selectively detect enzymatically-mediated antimicrobial resistance in undiluted urine.

The blood test is one of the most performed investigations in clinical practice, with samples typically analysed in a centralised laboratory. Many of these tests monitor routine conditions that would benefit from a point-of-care approach, reducing the burden on practitioners, patients and healthcare systems. Such a decentralised model requires the development of sophisticated, yet easy-to-use technology; however, platforms that combine high-performance with low-cost and simplicity remain scarce. Moreover, most research papers only address a subset of requirements and study specific aspects in isolation. A systems approach that considers the interplay between each element of the technology is clearly required to develop a coherent solution. Here, we present such a systems approach in the context of testing for C-reactive protein (CRP), a commonly requested test in clinical practise that indicates inflammation and is particularly relevant for monitoring patients with chronic diseases, e.g. those with rheumatoid arthritis or who are undergoing cancer therapy. The approach we take here features an entirely passive microfluidic cartridge for blood separation, integrated with a high-performance sensing platform which we have tested in a real-world context. The device is compatible with a handheld detection unit and is simple to use yet can accurately detect CRP levels at clinically relevant levels.