In Situ Growth of Mesoporous Silica with Drugs on Titanium Surface and Its Biomedical Applications

Growing vertical aligned mesoporous silica thin film on nanoporous substrate for enhanced degradation, drug delivery and bioactivity

Mesoporous silica thin film has been widely used in various fields, particularly the medical implant coating for drug delivery. However, some drawbacks remain with the films produced by traditional method (evaporation-induced self-assembly, EISA), such as the poor permeability caused by their horizontal aligned mesochannels. In this study, the vertical aligned mesoporous silica thin film (VMSTF) is uniformly grown alongside the walls of titania nanotubes array via a biphase stratification growth method, resulting in a hierarchical two-layered nanotubular structure. Due to the exposure of opened mesopores, VMSTF exhibits more appealing performances, including rapid degradation, efficient small-molecular drug (dexamethasone) loading and release, enhanced early adhesion and osteogenic differentiation of MC3T3-E1 cells. This is the first time successfully depositing VMSTF on nanoporous substrate and our findings suggest that the VMSTF may be a promising candidate for bone implant surface coating to obtain bioactive performances.

Biodegradable nanofibrous temperature-responsive gelling microspheres for heart regeneration

Myocardial infarction (heart attack) is the number one killer of heart patients. Existing treatments for heart attack do not address the underlying problem of cardiomyocyte (CM) loss and cannot regenerate the myocardium. Introducing exogenous cardiac cells is required for heart regeneration due to the lack of resident progenitor cells and very limited proliferative potential of adult CMs. Poor retention of transplanted cells is the critical bottleneck of heart regeneration. Here, we report the invention of a poly(l-lactic acid)-b-poly(ethylene glycol)-b-poly(N-Isopropylacrylamide) copolymer and its self-assembly into nanofibrous gelling microspheres (NF-GMS). The NF-GMS undergo thermally responsive transition to form not only a 3D hydrogel after injection in vivo, but also exhibit architectural and structural characteristics mimicking the native extracellular matrix (ECM) of nanofibrous proteins and gelling proteoglycans or polysaccharides. By integrating the ECM-mimicking features, injectable form, and the capability of maintaining 3D geometry after injection, the transplantation of hESC-derived CMs carried by NF-GMS led to a striking 10-fold graft size increase over direct CM injection in an infarcted rat model, which is the highest reported engraftment to date. Furthermore, NF-GMS carried CM transplantation dramatically reduced infarct size, enhanced integration of transplanted CMs, stimulated vascularization in the infarct zone, and led to a substantial recovery of cardiac function. The NF-GMS may also serve as advanced injectable and integrative biomaterials for cell/biomolecule delivery in a variety of biomedical applications.

Universal Strategy for Efficient Fabrication of Blood Compatible Surfaces via Polydopamine-Assisted Surface-Initiated Activators Regenerated by Electron Transfer Atom-Transfer Radical Polymerization of Zwitterions

Implant and blood-contacting biomaterials are challenged by biofouling and thrombus formation at their interface. Zwitterionic polymer brush coating can achieve excellent hemocompatibility, but the preparation often involves tedious, expensive, and complicated procedures that are designed for specific substrates. Here, we report a facile and universal strategy of creating zwitterionic polymer brushes on variety of materials by polydopamine (PDA)-assisted and surface-initiated activators regenerated by electron transfer atom-transfer radical polymerization (PDA-SI-ARGET-ATRP). A PDA adhesive layer is first dipcoated on a substrate, followed by covalent immobilization of 3-trimethoxysilyl propyl 2-bromo-2-methylpropionate (SiBr, ATRP initiator) on the PDA via condensation. Meanwhile, the trimethoxysilyl group of SiBr also cross-links the PDA oligomers forming stabilized PDA/SiBr complex coating. Finally, SI-ARGET-ATRP is performed in a zwitterionic monomer solution catalyzed by the parts per million level of CuBr₂ without deoxygenization. The conveniently fabricated zwitterionic polymer brush coatings are demonstrated to have stable, ultralow fouling, and extremely blood compatible and functionalizable characteristics. This facile, versatile, and universal surface modification strategy is expected to be widely applicable in various advanced biomaterials and devices.

A dual-responsive biosensor for blood lead detection

Simple and accurate detection of trace heavy metals in blood is very important. A novel dual-responsive electrochemical/fluorescent biosensor based on magnetic hyperbranched polyamide with heparin modification (MHPAM-H) for blood lead detection has been successfully developed. Upon conjugated with blood lead ions, dual-biosensor could not only display electrochemical signal but also fluorescence signal owing to the enriched amino groups, cavity structure, and good fluorescence properties of HPAM. Blood biocompatibility, construction of the dual-responsive biosensor, electrochemical/fluorescent detection of lead ions in water phase and blood condition, selectivity and stability of the dual-responsive biosensor were investigated in detail. The proposed dual-responsive biosensor displays good linear relationship (1.5 pM- 4.8 × 10³ pM for electrochemical detection and 0.5 pM-4.8 × 10³ pM for fluorescent detection) with low detection limit (4.4 pM for electrochemical detection and 1.0 pM for fluorescent detection) for blood lead, providing potential application for blood lead detection in the future.

Mesoporous Silica-Based Materials with Bactericidal Properties

Bacterial infections are the main cause of chronic infections and even mortality. In fact, due to extensive use of antibiotics and, then, emergence of antibiotic resistance, treatment of such infections by conventional antibiotics has become a major concern worldwide. One of the promising strategies to treat infection diseases is the use of nanomaterials. Among them, mesoporous silica materials (MSMs) have attracted burgeoning attention due to high surface area, tunable pore/particle size, and easy surface functionalization. This review discusses how one can exploit capacities of MSMs to design and fabricate multifunctional/controllable drug delivery systems (DDSs) to combat bacterial infections. At first, the emergency of bacterial and biofilm resistance toward conventional antimicrobials is described and then how nanoparticles exert their toxic effects upon pathogenic cells is discussed. Next, the main aspects of MSMs (e.g., physicochemical properties, multifunctionality, and biosafety) which one should consider in the design of MSM-based DDSs against bacterial infections are introduced. Finally, a comprehensive analysis of all the papers published dealing with the use of MSMs for delivery of antibacterial chemicals (antimicrobial agents functionalized/adsorbed on mesoporous silica (MS), MS-loaded with antimicrobial agents, gated MS-loaded with antimicrobial agents, MS with metal-based nanoparticles, and MS-loaded with metal ions) is provided.

Novel heparin-loaded mesoporous tubular micromotors formed via template-assisted electrochemical deposition

Based on the concept of the active drug delivery of micro- and nanomotors and the longer cycle time in the blood for drug-loaded tubular particles, it is important to develop novel tubular micromotors that could increase drug loading and achieve more effective treatments in the biomedical field. Here, a novel kind of mesoporous tubular micromotor used to load heparin (Hep) and formed via template-assisted electrochemical deposition is presented. Firstly, the mesoporous tubular micromotors were composed of poly(3,4-ethylenedioxythiophene) (PEDOT), mesoporous silica (MS) and manganese dioxide (MnO₂), and were simply fabricated via template-assisted electrochemical growth. Then, the drug Hep was loaded into PEDOT/MS/MnO₂via a simple soaking process. Finally, the release process, cytotoxicity, and blood compatibility tests and motion study for these mesoporous tubular micromotors of PEDOT/MS/MnO₂-Hep were performed. Results indicated that the micromotors we prepared showed good controlled release of Hep, anticoagulant effects, non-cytotoxicity and autonomous motion ability. The new drug carrier and motion mode will give rise to more potential applications of Hep in the biomedical field.

Porous Polymer Bearing Polyphenolic Organic Building Units as a Chemotherapeutic Agent for Cancer Treatment

Cancer is one of the most deadly diseases worldwide. Although several chemotherapeutic agents are available at present for its treatment, they have their own limitations. The main problems of these chemotherapeutic agents are cost involvement and severe life-threatening antagonistic effects. Here, we report a new biodegradable N-rich porous organic polymer methylenedianiline-triformyl phloroglucinol (MDTFP-1) synthesized via a Schiff base condensation reaction between two reactive monomers, that is, 4,4'-methylenedianiline and 2,4,6-triformyl phloroglucinol under inert atmosphere. Because this porous polymer contains polyphenolic building units and has a high Brunauer-Emmett-Teller surface area (283 m2 g-1), it has been explored in the anticancer activity using HCT 116, A549, and MIA PaCa-2 cell lines. We have carried out the flow cytometric assessment using Annexin-V-FITC/PI staining through the exposed level of phosphatidylserine in the outer membrane of cells with MDTFP-1-induced apoptosis. Our results suggested that apoptosis of cells have been enhanced in a time-dependent manner in the presence of this novel porous polymer.