Multicompartmental Microcapsules for Enzymatic Cascade Reactions Prepared through Gas Shearing and Surface Gelation.

Inspired by the structure of eukaryotic cells, multicompartmental microcapsules have gained increasing attention. However, challenges remain in the fabrication of "all-aqueous" (i.e., oil-free) microcapsules composed of accurately adjustable hierarchical compartments. This study reports on multicompartmental microcapsules with an innovative architecture. While multicompartmental cores of the microcapsules were fabricated through gas shearing, a shell was applied on the cores through surface gelation of alginate. Different from traditional multicompartmental microcapsules, thus obtained microcapsules have well-segregated compartments while the universal nature of the surface-gelation method allows us to finely tune the shell thicknesses of the microcapsules. The microcapsules are highly stable and cytocompatible and allow repeated enzymatic cascade reactions, which might make them of interest for complex biocatalysis or for mimicking physiological processes.

Colorimetric/spectral dual-mode analysis of sensitive fluorescent probe based on 2,3,3-trimethyl-3H-benzo[e]indole detection of acid pH.

Herein, a high-performance fluorescence probe, namely H4, based on intramolecular charge transfer (ICT) mechanism was developed. H4 could serve as fluorescent probe for detection acidic pH change in environment with outstanding sensitivity, short response time (<10 s), low hemolysis effect (<0.3%) and excellent photostability (>120 min). H4 exhibits a good linear relationship (R2 = 0.9901, Y = 22.0409X-58.3397) characteristics in range of pH 2.2-7.4 with pKa 4.3. In addition, the probe can be also made as fluorescent test sheets and further used as a portable sensor to enhance the screening speed to achieve detection of H+ in real-time. Further, H4 determined H+ in real food samples (milk, shrimps, and scallops) has excellent recoveries (98-105%), which making it of great potential use in food freshness evaluation. Initially, its favorable behavior for detecting H+ change is successfully illustrated in living onion tissues and zebrafish, which allows qualitative visualization of acid pH changes in in biological systems.

Prussian blue composite microswimmer based on alginate-chitosan for biofilm removal.

Bacterial infections pose a serious threat to public health, causing worldwide morbidity and about 80 % of bacterial infections are related to biofilm. Removing biofilm without antibiotics remains an interdisciplinary challenge. To solve this problem, we presented a dual-power driven antibiofilm system Prussian blue composite microswimmers based on alginate-chitosan, which designed into an asymmetric structure to achieve self-driven in the fuel solution and magnetic field. Prussian blue embedded in the microswimmers given it the ability to convert light and heat, catalyze Fenton reaction, and produce bubbles and reactive oxygen species. Moreover, with the addition of Fe3O4, the microswimmers could move in group under external magnetic field. The composite microswimmers displayed excellent antibacterial activity against S. aureus biofilm with an efficiency as high as 86.94 %. It is worth mentioning that the microswimmers were fabricated with device-simple and low-cost gas-shearing method. This system integrating physical destruction, chemical damage such chemodynamic therapy and photothermal therapy, and finally kill the plankton bacteria embedded in biofilm. This approach may cause an autonomous, multifunctional antibiofilm platform to promote the present most areas with harmful biofilm difficult to locate the surface for removal.

Chitosan enhanced the stability and antibiofilm activity of self-propelled Prussian blue micromotor.

The emergence, spread and difficult removal of bacteria biofilm, represent an ever-increasing persistent infections and medical complications challenge worldwide. Herein, a self-propelled system Prussian blue micromotor (PB MMs) were constructed by gas-shearing technology for efficient degradation of biofilms by combining chemodynamic therapy (CDT) and photothermal therapy (PTT). With the interpenetrating network crosslinked by alginate, chitosan (CS) and metal ions as the substrate, PB was generated and embedded in the micromotor at the same time of crosslinking. The micromotors are more stable and could capture bacteria with the addition of CS. The micromotors show excellent performance, containing photothermal conversion, reactive oxygen species (ROS) generation and bubble produced by catalyzing Fenton reaction for motion, which served as therapeutic agent could chemically kill bacteria and physically destroy biofilm. This research work opens a new path of an innovative strategy to efficiently remove biofilm.

Quaternized chitin/tannic acid bilayers layer-by-layer deposited poly(lactic acid)/polyurethane nanofibrous mats decorated with photoresponsive complex and silver nanoparticles for antibacterial activity.

Chronic wounding treatment based on bacterially infected diabetes suffers an essential limitation in persistent skin injuries due to the resistance of progressive antibiotics, which inhibits the process of healing with wound tissue. Therefore, biologically friendly and nontoxic bio-based mats without antibiotics are taken for granted as a versatile platform for biomedical dressing, but urgently necessitates further functional diversification. Herein, a novel tannic acid (TA)/silver (Ag)-modified poly(lactic acid) (PLA)/Polyurethane (PU) antibacterial hybrid nanofibers were successfully constructed by electrospinning technology. Layer-by-layer (LBL) self-assembly technique was utilized to produce membranes via deposited biocompatible quaternized chitin (QC) and TA. The mats are enabled with outstanding flexibility, antibacterial activity, great hemocompatibility, and good ROS-scavenger in a wounding environment. Consequently, the basis of morphology and structure of electrospun membranes was verified by SEM and FT-IR. Besides, the LBL-structured surface was proved to impart improved wettability and hydrophilic via the test of water contact angle. Additionally, antimicrobial experiments demonstrate the effective broad-spectrum antibacterial ability of as-prepared hybrids, inhibiting infection of gram-positive microbial (S. aureus) as well as gram-negative microbial. Finally, the anti-oxidation performance holds great promise in conducive to the formation favorable physiological environment for wound healing. In conclusion, this work establishes a feasible but effective pathway to construct a multifunctional antibacterial dressing for the skin infection.

A Prussian blue alginate microparticles platform based on gas-shearing strategy for antitumor and antibacterial therapy.

Prussian blue (PB) with distinct hollow mesoporous structure and favorable properties has captured the attention of extensive biomaterial researchers. However, there is an unmet need for biocompatible PB microparticles with recyclability fabricated by a facile method. Herein, a size-controlled PB alginate microparticles (PBAMs) generated by a one-step and large batch production gas-shearing strategy. With the characteristic of porous and surface-modifiable, PBAMs used as vehicles may effectively load and release drug to improve the therapeutic efficacy. Meanwhile, Fe2+ in PBAMs exerts a catalyze for chemodynamic therapy (CDT) to produce reactive oxygen species (ROS), which synergizes with the photothermal therapy (PTT) induced by PB particles with effective photothermal conversion, achieving active tri-modality combination antitumor and antibacterial. The new concept for the low-cost and facile preparation of biocompatible PBAMs here illustrated opens a novel pathway toward the effective multifunctional platform.

Spatial confinement of multi-enzyme for cascade catalysis in cell-inspired all-aqueous multicompartmental microcapsules.

Biocatalytic reaction networks in eukaryotic cells is realized by the immobilized and compartmental multi-enzymatic system. Inspired by the spatial localization of natural cells, multiple enzymes were confined within the multicompartmental microcapsules, which were created using a gas-shearing method coupled with surface-triggered in situ gelation strategy. Heterogeneous multicompartmental (two-, three-, four-, six-, or eight-faced) core particles, due to their capacity for positional assembly, were encapsuled in alginate hydrogel shells. The generated microcapsules integrate logic network to access complex digital design through a three-step convergent enzymatic cascade reaction as a model, and the capsules with high stability, recyclability and cytocompatibility are ideal enzymatic reactor systems to be used for biomimetic biocatalysis process.

Core-shell microparticles: From rational engineering to diverse applications.

Core-shell microparticles, composed of solid, liquid, or gas bubbles surrounded by a protective shell, are gaining considerable attention as intelligent and versatile carriers that show great potential in biomedical fields. In this review, an overview is given of recent developments in design and applications of biodegradable core-shell systems. Several emerging methodologies including self-assembly, gas-shearing, and coaxial electrospray are discussed and microfluidics technology is emphasized in detail. Furthermore, the characteristics of core-shell microparticles in artificial cells, drug release and cell culture applications are discussed and the superiority of these advanced multi-core microparticles for the generation of artificial cells is highlighted. Finally, the respective developing orientations and limitations inherent to these systems are addressed. It is hoped that this review can inspire researchers to propel the development of this field with new ideas.

"Turn-on" ratiometric fluorescent probe: Naked-eye detection of acidic pH and citric acid (CA) by using fluorescence spectrum and its application in real food samples and zebrafish.

Rapid, accurate and efficient detection of acidic pH and citric acid (CA) changes is of great significance for predicting environmental and food safety problems by fluorescence analysis technique. Herein, a small molecule ratiometric fluorescent probe (BICL) based on benzoindole derivatives is successfully synthesized and characterized and used for quantitatively and qualitatively "turn-on" detection acid pH and CA changes in solution and environment by ultraviolet spectrum and fluorescence emission spectrum. On the one hand, the probe has a good linear relation to acidic pH in the pH range 3.1-4.5 (I604/I550 = 13.088-2.3878pH, R2 = 0.9986). On the other hand, the probe has a good linear relationship in the range of CA concentration of 14.0-23.0 µM (I604/I550 = 0.5324 [CA]-5.2628, R2 = 0.9993) and a low detection limit of 2.967 µM. BICL has a good recovery rate in the range of 114.6 ~ 101.0% and a low relative standard deviation (RSD) (0.0011 ~ 0.0092) in the determination of CA in real samples (water, drinks and fruits), which holds great potential for application in determination of CA in real samples. Importantly, the probe has good blood compatibility, and it has been successfully applied to detect exogenously induced changes in acidic pH and CA in zebrafish with great time-stability by using fluorescence imaging technology, respectively.