Controlled Nutrient Delivery to Pancreatic Islets Using Polydopamine-Coated Mesoporous Silica Nanoparticles

Incorporating pH/NIR responsive nanocontainers into a smart self-healing coating for a magnesium alloy with controlled drug release, bacteria killing and osteogenesis properties

Magnesium (Mg)-based orthopedic implant materials can potentially be protected from deterioration using a protective polymer coating. However, this coating is susceptible to excessive corrosion and accidental scratches. Moreover, the inadequate bone integration and infections associated with bone implants present additional challenges that hinder their effective use. In this work, a spin-spray layer-by-layer (SSLbL) assembly technique was employed to develop a smart self-healing coating for Mg alloy WE43. This coating was based on paeonol-encapsulated nanocontainers (PMP) that were modified with a stimuli-responsive polydopamine (PDA). The leached paeonol could form a compact chelating layer when complexed with Mg2+ ions. Dynamic reversible hydrogen bonds were formed between assembly units, which ensured that the hybrid coating possessed rapid and cyclic self-healing properties. Under 808 nm near-infrared (NIR) laser irradiation, the self-healing coating exhibited antibacterial properties due to the synergistic effects of hyperthermia, reactive oxygen species (ROS), and paeonol. In addition, the incorporation of nanoparticles into the hybrid coating led to improvements in the cytocompatibility and osteogenic properties of the implant material. The smart coating enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization, and the expression of osteogenic genes. This study presents a promising opportunity to explore the application of a smart self-healing coating for a Mg alloy. STATEMENT OF SIGNIFICANCE: Herein, we report a self-healing coating comprised of polyethyleneimine and nanocontainer-crosslinked hyaluronic acid to achieve drug-controlled release, antimicrobial activity, and osteogenesis performance. The formation of hydrogen bonds between HA and PEI facilitated the self-assembly process, thereby improving the coating's corrosion resistance and adhesion strength. The hybrid coating exhibited a rapid and cyclic self-healing activity due to paeonol and dynamic reversible bonds. The release of paeonol was controlled by pH and NIR stimuli owing to polydopamine modification. In vitro testing revealed that the hybrid coating achieved effective bacteria eradication through synergistic effects of hyperthermia, reactive oxygen species, and paeonol. Moreover, the smart coating was found to enhance alkaline phosphatase activity, extracellular matrix mineralization, and the expression of osteogenic genes.

Survival, growth, behavior, hematology and serum biochemistry of mice under different concentrations of orally administered amorphous silica nanoparticle

Silica nanoparticles (SiNPs) are used extensively in consumer products and biomedical research basically due to ease of production and low cost. However, insufficient literature is reported regarding the toxicity and biocompatibility of SiNPs. The present study aimed to investigate the potential role of amorphous SiNPs on survival, growth, behavioral alterations, hematology and serum biochemistry of mice at four concentrations (control, 50, 100 and 150 mg/kg/day) of an oral supplementation for a period of 3 months. Signs of toxicity (lethargy, nausea, coma, tremors, vomiting and diarrhea, etc.) were noted at 9:00 am and 9:00 pm (twice a day) and the body weight of each of these mice was measured every week. The data were subjected to mean, standard deviation (S.D). Moreover, One-Way Analysis of Variance (ANOVA) and Dunnett's test were applied for analysis of statistical significance between groups by using SPSS software, version 20. All the mice survived with minor alterations in behavior and no significant weight changes were observed during the stipulated time period. Complete blood count (CBC) analysis indicated non-significant (P ≥ 0.05) systemic dysfunctions of organ systems. However, there was elevation in the level of AST and ALT in the analysis of serum biochemistry, while the values of all other examined parameters were not-significant (P ≥ 0.05). The study concluded that orally administered large silica nanoparticles up to the dose level of 150 mg/kg/day are nontoxic for the in vivo use in mice.

pH/thermal dual-responsive multifunctional drug delivery system for effective photoacoustic imaging-guided tumor chemo/photothermal therapy

The development of a combination of chemo/photothermal therapy could overcome the limitations of single-modality therapy and enhance therapeutic efficacy. In this study, a pH/thermal dual-responsive multifunctional drug delivery system with dual-drug loading and enhanced chemo/photothermal therapy is developed based on polydopamine-coated mesoporous silica-gold nanorods (PDA-AuNRs@MSN). Nanoscale mesoporous silica-gold nanorods encapsulating doxorubicin (DOX) are designed as a core and then modified by polydopamine. The PDA shell not only conjugates with another anticancer bortezomib (Btz) to form pH-sensitive bond through boronic acid and catechol but also acts as a gatekeeper to control the release of doxorubicin and enhance the photothermal effect. Such a nanocarrier not only acts as a contrast agent for PA imaging but also serves as a therapeutic agent for enhanced chemo/photothermal therapy. The DOX and Btz could be released in an on-demand mode under near-infrared light irradiation and acid environment. The tumor size and location could be observed via PA imaging after intravenous injection into 4T1-bearing mice. Compared with AuNRs@MSN, PDA-AuNRs@MSN exhibit an increased near-infrared (NIR) absorption at 808 nm and an enhanced photothermal effect. The integrated D/B-PDA-AuNRs@MSN nanoparticles show higher cell apoptosis and enhanced tumor treatment efficacy in vitro and in vivo in comparison with single chemotherapy or photothermal therapy. Combined together, D/B-PDA-AuNRs@MSN show pH/thermal-responsive controlled-release and synergistic chemo/photothermal therapy for tumor.

Promoting adsorption performance and mechanical strength in composite porous gel film

Starch is widely used to prepare biodegradable films due to its superior biocompatibility, low immunogenicity, and renewability. In this work, a novel K⁺/carrageenan porous-starch/casein gel film with high oil absorption was prepared using modified porous starch. Optimal gel stability and uniformity were obtained when adding 10 mg/mL k-carrageenan and 2 mg/mL K⁺ to 2 mg/mL microgels, with significantly reduced crystallinity and elasticity and increased tensile strength. The concentration of k-carrageenan was the main factor affecting gel strength and the hydrophilic and mechanical properties of the film. In addition, the film-forming solution showed excellent fluidity and spreading typical of non-Newtonian fluids. The film also exhibited a highly porous structure, as visualized by SEM and AFM, in line with a cumulative oil absorption rate of 87.5 % within 20 min, which was significantly higher than that obtained with glutinous rice starch. In conclusion, reinforcement of starch-based microgels as described in this study can maximize the film's adsorption performance and mechanical properties, with promising applications in skin care and beauty products.

Membrane-cloaked polydopamine modified mesoporous silica nanoparticles for cancer therapy

To improve the shortcomings of narrow therapeutic range and low bioavailability of traditional preparations, a composite drug carrier that combines the advantages of biological carriers and synthetic carriers was prepared in this project. The biomimetic nano-delivery system outer membrane vesicles-polydopamine-mesoporous silica nanoparticle (OMVs-PDA-MSN-DOX) for oral administration is composed of OMVs ofEscherichia colias shell and doxorubicin-loaded MSN modified by PDA as core. Several characterization techniques thoroughly examined the nano-drug delivery system to confirm its surface morphology and chemical property. OMVs-PDA-MSN-DOX with a particle size of 150 nm showed significant cell selectivity and safety. We demonstrated that OMVs are capable of protecting pH-sensitive nanostructure from the oral route of administration in the short term. Importantly, OMVs-PDA-MSN-DOX could facilitate intestinal adhesion and improve DOX bioavailability. Overall, the OMVs-cloaked nanocarrier provides an efficient delivery platform for the oral targeting treatment of cancer with pH-sensitive nano-formulations.

Drug molecules bridge with small gatekeeper to co-block mesoporous silica nanoparticles for drug delivery

In this study, a filter-like blocking system based on MSN with small gatekeeper 5- mercapto-2 nitrobenzoic acid (MNBA) has developed. The MNBA grafted nanoparticle MSN-SS-MNBA shows excellent blocking performance with negligible leakage when loaded with doxorubicin (DOX), and the release profiles illustrate stimuli-responsive property when triggered by GSH. Viability experiments indicate that MSN-SS-MNBA has obvious inhibition for both Hela cells and HCT116 cells, while showing good biocompatibility for L929 cells, which suggests that the modified MNBA has a synergistic effect on cancer cells-killing. Since the small grafted molecule MNBA cannot block the channels of MSN via self-assembly, a filter-like blocking model that the loaded drug bridged with modified MNBA to fulfill the blocking process is proposed. The novel blocking strategy provides a new possible way for pore blocking, and the small nanovalve can be used as synergistic molecule for cancer therapy.

A novel ultrasound-mediated nanodroplet-based gene delivery system for osteoporosis treatment

This project aimed to develop, optimize, and test an ultrasound-responsive targeted nanodroplet system for the delivery of osteoporosis-related silencing gene Cathepsin K small interfering RNA (CTSK siRNA) for osteoporosis treatment. The nanodroplet (ND) is composed of a gas core made from perfluorocarbon, stabilized with albumin, encapsulated with CTSK siRNA, and embedded with alendronate (AL) for bone targeting (CTSK siRNA-ND-AL). Following the development, the responsiveness of CTSK siRNA-ND-AL to a therapeutic ultrasound probe was examined. The results of biocompatibility tests with human bone marrow-derived mesenchymal stem cells proved no significant cell death (P > 0.05). When the CTSK siRNA-ND-AL was supplemented with human osteoclast precursors, they suppressed osteoclastogenesis. Thus, this project establishes the potential of nanotechnology and ultrasound to deliver genes into the osteoclasts. This research also presents a novel ultrasound responsive and targeted nanodroplet platform that can be used as a gene and drug delivery system for various diseases including cancer.

Applications and Biocompatibility of Mesoporous Silica Nanocarriers in the Field of Medicine

Mesoporous silica nanocarrier (MSN) preparations have a wide range of medical applications. Studying the biocompatibility of MSN is an important part of clinical transformation. Scientists have developed different types of mesoporous silica nanocarriers (MSNs) for different applications to realize the great potential of MSNs in the field of biomedicine, especially in tumor treatment. MSNs have achieved good results in diagnostic bioimaging, tissue engineering, cancer treatment, vaccine development, biomaterial application and diagnostics. MSNs can improve the therapeutic efficiency of drugs, introduce new drug delivery strategies, and provide advantages that traditional drugs lack. It is necessary not only to innovate MSNs but also to comprehensively understand their biological distribution. In this review, we summarize the various medical uses of MSN preparations and explore the factors that affect their distribution and biocompatibility in the body based on metabolism. Designing more reasonable therapeutic nanomedicine is an important task for the further development of the potential clinical applications of MSNs.

Localized drug delivery graphene bioscaffolds for cotransplantation of islets and mesenchymal stem cells

In the present work, we developed, characterized, and tested an implantable graphene bioscaffold which elutes dexamethasone (Dex) that can accommodate islets and adipose tissue–derived mesenchymal stem cells (AD-MSCs). In vitro studies demonstrated that islets in graphene–0.5 w/v% Dex bioscaffolds had a substantial higher viability and function compared to islets in graphene-alone bioscaffolds or islets cultured alone (P < 0.05). In vivo studies, in which bioscaffolds were transplanted into the epididymal fat pad of diabetic mice, demonstrated that, when islet:AD-MSC units were seeded into graphene–0.5 w/v% Dex bioscaffolds, this resulted in complete restoration of glycemic control immediately after transplantation with these islets also showing a faster response to glucose challenges (P < 0.05). Hence, this combination approach of using a graphene bioscaffold that can be functionalized for local delivery of Dex into the surrounding microenvironment, together with AD-MSC therapy, can significantly improve the survival and function of transplanted islets.

Research Progress on Polydopamine Nanoparticles for Tissue Engineering

Tissue engineering is an interdisciplinary field that aims to develop biological substitutes for the replacement, repair, or enhancement of tissue function. The physical and chemical characteristics of biomaterials exert a profound influence on the biological responses and the following biofunction. Nanostructured coatings have been widely applied as an effective surface modification strategy to improve the bioactivity of biomaterials. Especially, polydopamine and polydopamine-derived nanoparticles are found with excessive adhesiveness, redox activity, photothermal conversion capacity, paramagnetism and conductivity other than excellent biocompatibility, and hydrophilicity. In this article, advances about polydopamine nanoparticles in tissue engineering applications are reviewed, including the repair of bone, cartilage, skin, heart, and nerve, to provide strategies for future biomaterial design.

Construction of hollow polydopamine nanoparticle based drug sustainable release system and its application in bone regeneration

Nanomaterial-based drug sustainable release systems have been tentatively applied to bone regeneration. They, however, still face disadvantages of high toxicity, low biocompatibility, and low drug-load capacity. In view of the low toxicity and high biocompatibility of polymer nanomaterials and the excellent load capacity of hollow nanomaterials with high specific surface area, we evaluated the hollow polydopamine nanoparticles (HPDA NPs), in order to find an optimal system to effectively deliver the osteogenic drugs to improve treatment of bone defect. Data demonstrated that the HPDA NPs synthesized herein could efficiently load four types of osteogenic drugs and the drugs can effectively release from the HPDA NPs for a relatively longer time in vitro and in vivo with low toxicity and high biocompatibility. Results of qRT-PCR, ALP, and alizarin red S staining showed that drugs released from the HPDA NPs could promote osteogenic differentiation and proliferation of rat bone marrow mesenchymal stem cells (rBMSCs) in vitro. Image data from micro-CT and H&E staining showed that all four osteogenic drugs released from the HPDA NPs effectively promoted bone regeneration in the defect of tooth extraction fossa in vivo, especially tacrolimus. These results suggest that the HPDA NPs, the biodegradable hollow polymer nanoparticles with high drug load rate and sustainable release ability, have good prospect to treat the bone defect in future clinical practice.

Recent progress in the preparation, chemical interactions and applications of biocompatible polysaccharide-protein nanogel carriers

Nanogel carriers are rapidly emerged as a major delivery strategy in the fields of food, biology and medicine for small particle size, excellent solubility, high loading, and controlled release. Natural polysaccharides and proteins are selected for the preparation of biocompatible, biodegradable, low toxic, and less immunogenic nanogels. Different polysaccharides and proteins form complex nanogels through different interaction forces (e.g., electrostatic interaction and hydrophobic interaction). The present review pursues three aims: 1) to introduce several well-known dietary polysaccharides (chitosan, dextran and alginate) and proteins (whey protein and lysozyme); 2) to discuss the types, preparation methods, chemical interactions and properties of various biocompatible complex carriers; 3) to present the application and prospect of polysaccharide-protein complex in bioactive ingredient delivery, nutrient encapsulation and flavor protection. We expect that the integration with nano-intelligent technology will improve the functional ingredient loading, recognition specificity and controlled release capabilities of polysaccharide-protein nanocomposites to generate new intelligent nanogels in the field of food industry in the future.

Polydopamine-modified collagen sponge scaffold as a novel dermal regeneration template with sustained release of platelet-rich plasma to accelerate skin repair: A one-step strategy

Although employed to release growth factors (GFs) for regenerative medicine, platelet-rich plasma (PRP) has been hindered by issues like burst effect. Based on collagen sponge scaffolds (CSSs) modified with polydopamine (pDA), a novel dermal regeneration template (DRT) was designed. However, whether it could efficiently deliver PRP and even foster wound healing remained unclear. In this work, after PRP was prepared and pDA-modified CSSs (pDA-CSSs) were fabricated, microscopic observation, GFs release assay and in-vitro biological evaluations of pDA-CSSs with PRP (pDA-CSS@PRP) were performed, followed by BALA-C/nu mice full-thickness skin defects implanted with pDA-CSS@PRP covered by grafted skins (termed as a One-step strategy). As a result, scanning electron microscope demonstrated more immobilized platelets on pDA-CSS' surface with GFs' controlled release via enzyme-linked immunosorbent assay, compared with CSSs. In line with enhanced in-vitro proliferation, adhesion and migration of keratinocytes & endothelial cells, pDA-CSS@PRP were histologically revealed to accelerate wound healing with less scar via rapid angiogenesis, arrangement of more mature collagen, guiding cells to spread, etc. In conclusion, pDA-CSSs have potential to serve as a novel DRT capable of delivering PRP, which may foster full-thickness skin defect healing by means of a One-step strategy.

Polydopamine-based nanomaterials and their potentials in advanced drug delivery and therapy

Polydopamine (PDA) has shown great potentials in biomedical fields due largely to its unique physicochemical properties, including high photothermal transfer efficiency, excellent drug binding capacity, versatile adhesion ability, sensitive pH responsibility and great biocompatibility and biodegradability. These properties confer PDA-based nanoparticles the potentials either as the drug carriers for advanced drug delivery or as the bioactive agents for photothermal therapy, imaging and biosensing. This review aims to provide a comprehensive understanding of PDA, its polymerization mechanisms and the potentials of PDA-based nano-systems in treating various diseases, including cancer, diabetes, inflammation, bacterial infection and Parkinson's disease. In addition, the concerns of PDA in biomedical use are also discussed.