Nano-in-Micro Smart Hydrogel Composite for a Rapid Sensitive Immunoassay

Synthesizing Submicron Polyelectrolyte Capsules to Boost Enzyme Immobilization and Enhance Enzyme-Based Immunoassays

Polyelectrolyte capsules (PCs) exhibit attractive superiorities in enzyme immobilization, including providing a capacious microenvironment for enzyme conformational freedom, highly effective mass transfer, and protecting enzymes from the external environment. Herein, we provide the first systemic evaluation of submicron PCs (SPCs, 500 nm) for enzyme immobilization. The catalytic kinetics results show that SPC encapsulation affected the affinities of enzymes and substrates but significantly enhanced their catalytic activity. The stability test indicates that SPC-encapsulated horseradish peroxidase (HRP) exhibits ultrahigh resistance to external harsh conditions and has a longer storage life than that of soluble HRP. The proposed encapsulation strategy enables 7.73-, 2.22-, and 11.66-fold relative activities when working at a pH as low as 3, at a NaCl concentration as high as 500 mM, and at a trypsin concentration as high as 10 mg/mL. We find that SPC encapsulation accelerates the cascade reaction efficiency of HRP and glucose oxidase. Owing to SPCs enhancing the catalytic activity of the loaded enzymes, we established an amplified enzyme-linked immunosorbent assay (ELISA) for the detection of Escherichia coli O157:H7 using HRP-loaded SPCs. The detection sensitivity of SPC-improved ELISA was found to be 280 times greater than that of conventional HRP-based ELISA. Altogether, we provide an elaborate evaluation of 500 nm SPCs on enzyme immobilization and its application in the ultrasensitive detection of foodborne pathogens. This evaluation provides evidence to reveal the potential advantage of SPCs on enzyme immobilization for enzyme-based immunoassays. It has excellent biological activity and strong stability and broadens the application prospect in urine, soy sauce, sewage, and other special samples.

Tuneable Cell-Laden Double-Emulsion Droplets for Enhanced Signal Detection

Water-in-oil-in-water (w/o/w) or double-emulsion (DE) droplets have been widely used for cellular assays at a single-cell level because of their stability and biocompatibility. The oil shell of w/o/w droplets plays the role of a semipermeable membrane that allows substances with low molecular weight (e.g., water) to travel through but restricts those with high molecular weight (e.g., fluorescent biomarkers). Therefore, the core of DEs can be manipulated using osmosis, resulting in the shrinking or swelling of the core. Water leaves the inner aqueous phase to the outer phase via the oil shell when the osmotic pressure of the outer phase is higher than that in the inner phase, causing the shrinkage of DEs and vice versa. These processes can be achieved by transferring the DEs to hypertonic or hypotonic solutions. Manipulation of the core size of DEs can be beneficial to cellular assays. First, due to the selectivity of the oil shell of DEs, the concentration of biomarkers in the core increases when the inner aqueous phase is shrunk, resulting in the enhancement of biosignals. We demonstrate this by encapsulating the Bgl3 enzyme-secreting yeast with a substrate that displays fluorescence after hydrolyzation. In a second application, a single GFP-tagged yeast cell was encapsulated in DEs. After swelling the core of DEs, we observe that the larger core of DEs promotes cell growth compared to those with the smaller cores, leading to more intracellular proteins (green-fluorescent protein) for screening. These osmotic manipulations provide new tools for droplet-based biochemistry.

PEG-based Cleavable Hydrogel Microparticles with controlled porosity for permiselective trafficking of biomolecular complexes in biosensing applications

In the last decade, PEG-based hydrogels have been extensively used for the production of microparticles for biosensing applications. The biomolecule accessibility and mass transport rate represent key parameters for the...

Nanoplatforms for Sepsis Management: Rapid Detection/Warning, Pathogen Elimination and Restoring Immune Homeostasis

Sepsis, a highly life-threatening organ dysfunction caused by uncontrollable immune responses to infection, is a leading contributor to mortality in intensive care units. Sepsis-related deaths have been reported to account for 19.7% of all global deaths. However, no effective and specific therapeutic for clinical sepsis management is available due to the complex pathogenesis. Concurrently eliminating infections and restoring immune homeostasis are regarded as the core strategies to manage sepsis. Sophisticated nanoplatforms guided by supramolecular and medicinal chemistry, targeting infection and/or imbalanced immune responses, have emerged as potent tools to combat sepsis by supporting more accurate diagnosis and precision treatment. Nanoplatforms can overcome the barriers faced by clinical strategies, including delayed diagnosis, drug resistance and incapacity to manage immune disorders. Here, we present a comprehensive review highlighting the pathogenetic characteristics of sepsis and future therapeutic concepts, summarizing the progress of these well-designed nanoplatforms in sepsis management and discussing the ongoing challenges and perspectives regarding future potential therapies. Based on these state-of-the-art studies, this review will advance multidisciplinary collaboration and drive clinical translation to remedy sepsis.