Straightforward neuron micropatterning and neuronal network construction on cell-repellent polydimethylsiloxane using microfluidics-guided functionalized Pluronic modification.

Neuronal cell microengineering involving micropatterning and polydimethylsiloxane (PDMS) microfluidics enables promising advances in microscale neuron control. However, a facile methodology for the precise and effective manipulation of neurons on a cell-repellent PDMS substrate remains challenging. Herein, a simple and straightforward strategy for neuronal cell patterning and neuronal network construction on PDMS based on microfluidics-assisted modification of functionalized Pluronic is described. The cell patterning process simply involves a one-step microfluidic modification and routine in vitro culture. It is demonstrated that multiple types of neuronal cell arrangements with various spatial profiles can be conveniently produced using this patterning tool. The precise control of neuronal cells with high patterning fidelity up to single cell resolution, as well as high adhesion and differentiation, is achieved too. Furthermore, neuronal network construction using the respective cell population and single cell patterning prove to be applicable. This achievement provides a convenient and feasible methodology for engineering neuronal cells on PDMS substrates, which will be useful for applications in many neuron-related microscale analytical research fields, including cell engineering, neurobiology, neuropharmacology, and neuronal sensing.

Branched Ubiquitination: Detection Methods, Biological Functions and Chemical Synthesis.

Ubiquitination is a versatile posttranslational modification that elicits signaling roles to impact on various cellular processes and disease states. The versatility is a result of the complexity of ubiquitin conjugates, ranging from a single ubiquitin monomer to polymers with different length and linkage types. Recent studies have revealed the abundant existence of branched ubiquitin chains in which one ubiquitin molecule is connected to two or more ubiquitin moieties in the same ubiquitin polymer. Compared to the homotypic ubiquitin chain, the branched chain is recognized or processed differently by readers and erasers of the ubiquitin system, respectively, resulting in a qualitative or quantitative alteration of the functional output. Furthermore, certain types of branched ubiquitination are induced by cellular stresses, implicating their important physiological role in stress adaption. In addition, the current chemical methodologies of solid phase peptide synthesis and expanding genetic code approach have been developed to synthesize different architectures of branched ubiquitin chains. The synthesized branched ubiquitin chains have shown their significance in understanding the topologies and binding partners of the branched chains. Here, we discuss the recent progresses on the detection, functional characterization and synthesis of branched ubiquitin chains as well as the future perspectives of this emerging field.

Degradable and self-luminescence porous silicon particles as tissue adhesive for wound closure, monitoring and accelerating wound healing.

Tissue adhesives have received much attention for their effectiveness in sealing wounds or incisions in clinical surgery, especially in minimally invasive surgery. To meet the safe and smart wound management requirements, ideal tissue adhesives are expected to have high biocompatibility, and be able to accelerate wound closing and healing, and monitor wound healing process. However, few adhesives fit all of the above descriptions. It has been demonstrated that inorganic nanoparticles can directly glue biological tissue based on nano-bridging effect. In this study, self-luminescence porous silicon (LPSi) particles were prepared with degradable and biocompatible properties. In addition, the self-luminescence property of LPSi particles was discovered by In Vivo Imaging System (IVIS) for the first time, which can avoid the limitations of photoluminescence imaging. Due to the oxidation and degradation reaction, LPSi particles not only can be degraded completely in several days, but also showed satisfactory biocompatibility. And their degradation product could promote tube formation of HUVECs. Moreover, owing to the high specific surface area and the outer oxide layer of LPSi particles, LPSi tissue adhesive exhibited strong adhesive strength to pig livers. Furthermore, this adhesive closed wound rapidly, promoted angiogenesis and epidermal regeneration, and facilitated wound healing in a mouse skin incision model. Importantly, the wound healing ratio can be monitored by measuring the self-luminescence intensity of LPSi particles in the wound site. This study reveals that LPSi particles could be employed as a safe and smart wound management tissue adhesive for wound closure, as well as accelerating and monitoring wound healing.

Gelatin-based adhesive hydrogel with self-healing, hemostasis, and electrical conductivity.

As a kind of natural protein derived material, gelatin has been widely used in the preparation of medical hydrogels due to its good biocompatibility, non-immunogenicity and the ability of promoting cell adhesion. Functionalization of gelatin-based hydrogels is a hot topic in research and its clinic application. Herein, a novel gelatin-based adhesive hydrogel was prepared via mussel-inspired chemistry. Gelatin was firstly functionalized by dopamine to form dopamine grafted gelatin (GelDA). After the mixture with 1,4-phenylenebisboronic acid and graphene oxide (GO), the GelDA/GO hydrogels were obtained by H2O2/HRP (horseradish peroxidase) catalytic system. Based on the self-healing and tissue adhesion of the hydrogels, the hemostatic property has been exhibited in the rat hepatic hemorrhage model. Additionally, the incorporation of GO endowed conductivity and enhanced the mechanical property of GelDA/GO hydrogels. The electromyography (EMG) signals of finger movement were successfully monitored by using hydrogel as the adhesive electrodes of EMG monitor. L929 cell experiments showed that the hydrogels had good cytocompatibility. The results indicated the potential application of GelDA/GO hydrogels in tissue adhesives, wound dressings, and wearable devices.

Study on hemostatic effect and mechanism of starch-based nano-microporous particles.

The powdered hemostatic particles have broad application prospects in large open wounds, internal organ injuries and penetrating injuries of the body. In this study, nanoscale mescoporous and macroporous silica (MMSN), nanoscale mescoporous and macroporous bioactive glass (MBG), micron-scale cross-linked corn starch porous microspheres (CMS), MMSN@CMS and MBG@CMS starch-based nano-microporous particles were synthesized and their hemostatic effect and hemostatic mechanism were studied. The results showed that comparted with the single particle of CMS, the combination particles MBG@CMS and MMSN@CMS significantly increased the water absorption rate, activated both internal and external coagulation pathways, significantly shortened CBT, as well as the improved hemostatic effects in vitro. The immediately released Ca2+ from MBG@CMS in the blood to participate in the coagulation pathway, and MMSN@CMS activated platelets by concentrating blood coagulation factors, might be the main hemostatic mechanisms for the starch-based nano-microporous particles. Furthermore, the hemostatic efficacy of particles, both in the model of tail-amputation and liver injury in SD rats, showed the starch-based nano-microporous particles, especial MBG@CMS, could significantly reduce the weight of blood loss and shorten the bleeding time. Our research work stated that the starch-based nano-microporous particles MBG@CMS might be a hemostasis biomaterial with the potential applications for the emergency bleeding.

Research status and development potential of composite hemostatic materials.

Bleeding is a serious incident that can occur in people's daily lives or clinics. Bleeding can be caused by accidental trauma, surgery, congenital diseases, or blood disorders caused by drugs. Excessive bleeding in the body can lead to illness or death. Adequate hemostasis is an essential strategy to prevent bleeding to avoid death and is the first step in wound healing. With rapid developments in science and technology, various hemostatic materials have been developed with the hope of enhancing the hemostatic effect by activating different coagulation mechanisms. Some examples are the formation of physical barriers, platelet aggregation, concentration of blood components, and release of clotting factors. The design of composite hemostatic materials should conform to the requirement according to which multiple coagulation mechanisms can be simultaneously activated in order to enhance the hemostatic effect. Combined with the research status of composite hemostatic materials, it has been found that there is still a lack of materials that exhibit high biocompatibility, shape variability, simultaneous usability for both internal and external bleeding, in vivo degradability, ability to camouflage platelets or blood cells, and other clotting-related factors. Therefore, the future development potential and optimization direction for composite hemostatic materials have been proposed through an in-depth discussion on their characteristics and coagulation mechanisms. It is hoped that this review can provide a worthwhile reference for research into hemostatic materials.

Enhancement and control of neuron adhesion on polydimethylsiloxane for cell microengineering using a functionalized triblock polymer.

Polydimethylsiloxane (PDMS)-based neuron microengineering provides new opportunities for spatiotemporal control of neuronal activity and stimuli. The demand for long-lasting adhesive PDMS surfaces has steered the development of straightforward, feasible, and accessible interface modifications. Here, we describe an innovative approach for promoting and engineering neuron adhesion on a PDMS substrate based on a very simple modification using poly-d-lysine-conjugated Pluronic F127, a functionalized triblock polymer. The modification procedure only involves single-step pipetting or microfluidic-guided introduction for the reinforcement of cell adhesion in quantity, extensibility, and stability. Micropatterning at a single-cell resolution, microfluidic long-term culture, and neuron network formation were achieved. The present approach provides a previously unprecedented simple and effective technique for neuron adhesion on PDMS and may be useful for applications in neurobiology, tissue engineering, and neuronal microsystems.

[Acute and chronic toxicity of 0.5% podophyllotoxin-loaded nanostructured lipid carriers to vaginal mucosa in rabbits and rats].

OBJECTIVE: To test the acute and chronic toxicity of topical application of 0.5% podophyllotoxin-loaded nanostructured lipid carriers (POD-NLC) to the vaginal mucosa. METHODS: Twelve New Zealand rabbits were randomized into 3 groups and subjected to daily topical applications of normal saline (control group), 0.5% podophyllotoxin tincture (POD-T) or 0.5% POD-NLC on the vaginal mucosa for 10 consecutive days, and the pathological changes in the mucosa were graded using the Eckstein scoring system.The acute toxicity of POD-NLC was tested in 20 SD female rats, which received intravaginal administration of POD-NLC or vehicle for 3 times within 24 h; After 14 days of continuous observation, the rats were dissected for calculating the viscera coefficient.For testing the chronic toxicity of POD-NLC, 80 SD female rats were randomized into 4 groups and subjected to daily intravaginal administration of the vehicle or POD-NLC at low, moderate or high doses for 13 consecutive weeks.The rats were weighed once a week and at the end of the experiment, 2/3 of the rats from each group were sacrificed to collect blood samples, calculate the viscera coefficient, and examine the pathological changes in the liver.The remaining 1/3 rats were observed for another 2 weeks without further drug treatment and the same examinations were performed. RESULTS: In the rabbits, 0.5% POD-NLC elicited only mild irritation while POD-T caused moderate irritation of the vaginal mucosa.In the acute toxicity test, the organ coefficients were comparable between the rats treated with the vehicle and POD-NLC (P>0.05).Long-term intravaginal administration of POD-NLC did not produce significant changes in the behavior, activity, body weight, blood biochemical profiles or organ coefficient as compared with the vehicle control group (P>0.05). CONCLUSIONS: Intravaginal administration of 0.5% POD-NLC causes very mild irritation without obvious acute or chronic toxicity to the vaginal mucosa in rabbits and rats.

pH-Responsive Nanoscale Coordination Polymer for Efficient Drug Delivery and Real-Time Release Monitoring.

Both excess dosages of drug and unwanted drug carrier can lead to severe side effects as well as the failure of tumor therapy. Here, an Fe3+ -gallic acid based drug delivery system is designed for efficient monitoring of drug release in tumor. Fe3+ and polyphenol gallic acid can form polygonal nanoscale coordination polymer in aqueous solution, which exhibits certain antitumor effect. Importantly, this coordination polymer possesses extremely high doxorubicin (DOX) loading efficacy (up to 48.3%). In vitro studies demonstrate that the fluorescence of DOX can be quenched efficiently when DOX is loaded on the coordination polymer. The acidity in lysosome also triggers the release of DOX and fluorescence recovery simultaneously, which realizes real-time monitoring of drug release in tumor cells. In vivo studies further indicate that this polyphenol-rich drug delivery system can significantly inhibit tumor growth with negligible heart toxicity of DOX. This system with minimal side effects should be a promising nanoplatform for tumor treatment.

Dual stimuli-responsive multi-drug delivery system for the individually controlled release of anti-cancer drugs.

A dual stimuli-responsive multi-drug delivery system was developed for "cancer cocktail therapy". Upon UV irradiation, microcapsules could rapidly release the small-molecule drugs, and thereafter the macromolecular drugs would be released in the presence of MMP in the tumor cells. This system will find great potential as a novel chemotherapeutic combination for cancer treatment.

Photo-Activatable Substrates for Site-Specific Differentiation of Stem Cells.

In this report, a UV sensitive, PEGylated PFSSTKTC (Pro-Phe-Ser-Ser-Thr-Lys-Thr-Cys) peptide was modified on quartz substrate to investigate the spatial controlled differentiation of stem cells. This substrate could restrict the cell adhesion due to the steric hindrance of PEG shell. With UV irradiation, PFSSTKTC became exposed owing to the breakage of o-nitrobenzyl group with the detachment of PEG shell. The irradiation boundary on substrate was stable in the long term. The in vitro osteogenic differentiation results revealed that under the site-specific irradiation, the mesenchymal stem cells (MSCs) could specifically differentiate into osteoblast under the induction of PFSSTKTC peptide. This photoactivatable biomaterial shows great potential for region controllable and precise MSCs differentiation.