Tea polyphenol carrier-enhanced dexamethasone nanomedicines for inflammation-targeted treatment of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by synovial inflammation, cartilage damage and bone erosion. In the progression of RA, the inflammatory mediators including ROS, NO, TNF-α, and IL-6 play important roles in the aggravation of inflammation. Hence, reducing the generation and release of inflammatory mediators is of great importance. However, the high dose and frequent administration of clinical anti-inflammatory drugs such as glucocorticoids (GCs) usually lead to severe side effects. The development of nanotechnology provides a promising strategy to overcome these issues. Here, polyphenol-based nanoparticles with inherent anti-oxidative and anti-inflammatory activities were developed and used as a kind of nanocarrier to deliver dexamethasone (Dex). The in vitro experiments confirmed that the nanoparticles and drugs could act synergistically for suppressing inflammatory mediators in the LPS/INF-γ-induced inflammatory cell model. After intravenous administration, the Dex-loaded nanoparticles with good biosafety showed effective accumulation in inflamed joints and improved therapeutic efficacy by inducing anesis of synovial inflammation and cartilage destruction over free Dex in a collagen-induced arthritis (CIA) mouse model. The results demonstrated that polyphenol-based nanoparticles with therapeutic functions may serve as an innovative platform to synergize with chemotherapeutic agents for enhanced treatment of inflammatory diseases.

Biocompatible, bacteria-targeting resveratrol nanoparticles fabricated by Mannich molecular condensation for accelerating infected wound healing.

Excessive reactive oxygen species (ROS) and long-term inflammation can delay wound healing and cause tissue damage, while bacterial infection aggravates the wound environment further. It is impossible to resolve all these thorny problems simultaneously with a wound dressing that has only one function. The antioxidative and anti-inflammatory properties of resveratrol (Res) have been proven. However, the effect of Res is non-selective, and high levels of Res can inhibit cell growth and promote oxidation. Res is also difficult to dissolve and possesses insufficient antibacterial properties, so its role is limited. In this study, Res was assembled via Mannich reaction into nanoparticles and functionalized by phenylboric acid, giving rise to targeting bacteria and solving the water-insoluble dilemma of Res. In comparison with Trolox, the assembled Res NPs performed better at scavenging ABTS and DPPH free radicals. Furthermore, Res NPs that targeted bacteria also showed high biocompatibility at concentrations five times higher than pure Res. The activities of Res NPs were comparable to free Res in downregulating the expression of inflammatory cytokines, and reducing intracellular excessive ROS. The gel embedded with Res NPs accelerated the formation of granulation tissue, collagen deposition, and re-epithelialization, facilitating wound healing. The present study suggests that functionalized polyphenol-based materials are preferably suited to the development of tissue engineering biomaterials.

Injectable oxidized alginate/carboxylmethyl chitosan hydrogels functionalized with nanoparticles for wound repair.

Owing to its simple properties, the application of injectable hydrogel in wound repair is limited. Therefore, the multi-functionalization of injectable hydrogel to improve the therapeutic effect is imperative. Here, keratin nanoparticles (Ker NPs) with facilitating epithelization capability and nanosized-EGCG covered with Ag nanoparticles (AE NPs) with radicals scavenging capability were used to functionalize injectable oxidized alginate/carboxylmethyl chitosan hydrogel (KA hydrogel). The radical scavenging experiments proved the anti-oxidative capacity of AE NPs. Rheological test exhibited that the gelation time and storage modulus of KA hydrogel were about 216 s and 403 Pa. Additionally, wound healing experiment in vivo showed that KA hydrogel could accelerated wound healing, especially in the early stage, and improved the thickness of renascent epidermis by 21 %. In this work, Ker NPs and AE NPs functionalization endowed injectable hydrogels with the capabilities of scavenging radicals and facilitating epithelization, which is promising for the applications in wound repair.

Injectable hyaluronic acid/hydroxyapatite composite hydrogels as cell carriers for bone repair.

The natural polysaccharide/hydroxyapatite hydrogels are of great interest to bone tissue engineering, but the interfacial mismatch between rigid hydroxyapatite and soft polysaccharide phase in these hydrogels remains unsolved, which is unfavorable to achieving uniform dispersion of hydroxyapatite particles in the hydrogel matrices. Herein, hyaluronic acid (Hya), an extracellular matrix constituent, was chosen as the template for biological mineralization to synthesize Hya/hydroxyapatite hybrid particles (HAHs). The oxidized Hya/hydroxyapatite hybrid particles (OHAHs) were obtained by oxidating the Hya in the HAHs. These OHAHs were the ball-flower particles hybridized with ca. 22 % oxidized Hya. Then, different concentrations of OHAHs were introduced to prepare hydroxyapatite composite hydrogels (HCH) via Schiff-base reaction of oxidized Hya and carboxymethyl chitosan. The injectability and self-healing of HCH were evaluated and the introduction of OHAHs significantly increased the storage modulus. The gelation time of HCH showed a negative relation with the concentration of OHAHs while the storage modulus presented a positive correlation. MTT assays and live/dead staining of L929 cells co-cultured with HCH confirmed that the hydrogels had excellent cytocompatibility, and supported the adhesion and proliferation of cells under the three-dimension culture conditions. These injectable self-healing hydrogels suitable for cell encapsulation were potentially useful for bone defect repair.

Size Changeable Nanomedicines Assembled by Noncovalent Interactions of Responsive Small Molecules for Enhancing Tumor Therapy.

The size of nanocarriers strongly affects their performance in biological systems, especially the capacity to overcome various barriers before delivering the payloads to destinations. However, the optimum size varies at different delivery stages in cancer therapy due to the complicated tumor microenvironment. Relatively large particles are favored for long-term circulation in vivo, while smaller particles contribute to deep penetration into tumor tissues. This dilemma in the size of particles stimulates the development of stimuli-responsive size-shrinking nanocarriers. Herein, we report a facile strategy to construct a tumor-triggered tannic acid (TA) nanoassembly with improved drug delivery efficiency. Cystamine (CA), a small molecule with a disulfide bond, is thus used to mediate TA assembling via cooperative noncovalent interactions, which endows the nanoassembly with intrinsic pH/GSH dual-responsiveness. The obtained TA nanoassemblies were systematically investigated. DOX encapsulated nanoassembly labeled TCFD NP shows high drug loading efficiency, pH/GSH-responsiveness and significant size shrinkage from 122 to 10 nm with simultaneous drug release. The in vitro and in vivo experimental results demonstrate the excellent biocompatibility, sufficient intracellular delivery, enhanced tumor retention/penetration, and superior anticancer efficacy of the small-molecule-mediated nanoassembly. This noncovalent strategy provides a simple method to fabricate a tumor-triggered size-changeable delivery platform to overcome biological barriers.

Developing exquisite collagen fibrillar assemblies in the presence of keratin nanoparticles for improved cellular affinity.

Recently, the collagen-keratin (CK) composites have received much attention for the purpose of biomedical applications due to the intrinsic biocompatibility and biodegradability of these two proteins. However, few studies have reported the CK composites developed by the self-assembly approach and the influence of the keratin on the collagen self-assembly in vitro was still unknown. In this study, the keratin nanoparticles (KNPs) were successfully prepared by the reduction method, and we focused on investigating the effect of the varying concentrations of KNPs on the mechanism of the fibrillogenesis process of collagen. The intermolecular interaction between the two proteins revealed by the ultraviolet spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy and circular dichromatic (CD) spectroscopy showed that KNPs would interact with the collagen, and keratin significantly influenced the hydrogen bonding interaction existed in collagen molecules. The SEM images exhibited the formation of exquisite fibrillar networks after incorporating the KNPs into collagen, and it was conspicuous that the KNPs could uniformly distribute on the surface of collagen fibrils via electrostatic interaction, for both of the two proteins possessed many charged moieties. In addition, the AFM images confirmed the presence of the characteristic D-periodicity of collagen fibrils, indicating that the introduction of KNPs did not disrupt the self-assembly nature of the native collagen. The cell adhesion, proliferation and migration experiments on the CK fibrils were also performed in this study. The results demonstrated that the CK composites showed a better cellular affinity compared with the collagen, thus it might be a promising candidate for the biomedical applications.

Insight into the effect of sulfonated chitosan on the structure, rheology and fibrillogenesis of collagen.

As a heparin analogue, sulfonated chitosan (SCS) has been confirmed to have similar structure and properties to heparin which is shown to be a linker molecule having specific binding sites with collagen fibrils. In this study, the effects of a varying concentration of SCS on the self-assembly process of type I collagen were investigated. The study on intermolecular interaction between collagen and SCS was carried out via using ultraviolet-visible (UV-vis) spectrophotometry and circular dichroism (CD) spectroscopy. The addition of SCS did not disrupt the triple helix conformation of collagen. However, the decreased value of Rpn showed that the SCS, to some extent, influenced the percentage of triple helix conformation. The turbidity measurements revealed that the self-assembly rate was increased in the presence of a low concentration of SCS whereas decreased with further increasing the SCS concentration. The observation of microstructure via scanning electron microscopy (SEM) and atomic force microscopy (AFM) exhibited the characteristic D-periodicity, indicating that the presence of SCS did not disrupt the self-assembly nature of collagen. Moreover, the addition of SCS facilitated the lateral aggregation of fibrils, leading to the formation of larger fibrils. The rheological analysis showed that the gelation time of collagen was prolonged with increasing the concentration of SCS, in support of a longer lag-phase duration detected in turbidimetric measurements. We expect that valuable data would be provided in this study for further developing of ECM analogues, and propitious performances could be endowed to these biomimetic materials after SCS incorporation.

Synthesis and characterization of injectable self-healing hydrogels based on oxidized alginate-hybrid-hydroxyapatite nanoparticles and carboxymethyl chitosan.

Injectable hydrogels are of great interest in tissue engineering, and those incorporating hydroxyapatite (HA) are especially acclaimed in the application of bone repair. Synthetic micro-HA were generally used for this purpose and in some cases, surface modification of HA was further applied to improve the interfacial compatibility of rigid inorganic HA with soft organic matrix. In this study, the injectable hydrogels based on oxidized alginate hybrid HA nanoparticles and carboxymethyl chitosan were achieved via Schiff base reaction. Physicochemical characterization confirmed that oxidized HA/Alg hybrids (OHAH) were successfully prepared. Rheological measurements verified the formation of hydrogels based on the dynamic imine bonding, and the gelation time showed a negative correlation to the concentration and oxidation time of OHAH, while the storage moduli exhibited a positive correlation. The self-healing property of these hydrogels was validated by the splicing experiments and rheological experiments. The lyophilized hydrogels showed porous structures with numerous HA nanoparticles distributed on the surface of pore wall. MTT assays and live/dead staining of cell experiments confirmed the cytocompatibility of these hydrogels. The injectable hydrogels with self-healing and tunable gelling properties were ingeniously prepared with functionalized alginate-mediated HA hybrid nanoparticles, and these hydrogels are promising for applications in bone tissue engineering.

General Nanomedicine Platform by Solvent-Mediated Disassembly/Reassembly of Scalable Natural Polyphenol Colloidal Spheres.

The current strategy using the assembly of medicines and active functional molecules to develop nanomedicines often requires both molecules to have a specific matched chemical molecular structure; however, this is often difficult to predict, execute, and control in practical applications. Herein, we reported a general solvent-mediated disassembly/reassembly strategy for preparing nanomedicines based on epigallocatechin gallate (EGCG) active molecules. The polyphenol colloidal spheres (CSs) were self-assembled from molecular condensed EGCG in aqueous solution but disassembled in organic solvents and reassembled in aqueous solution. The solvent-mediated disassembly and reassembly capability of CSs gave rise to the active binding of condensed EGCG to various hydrophilic and hydrophobic guest molecules. The maximum encapsulation and drug-loading rate of reassembled CSs/DOX were 90 and 44%, respectively, and the nanomedicines could reverse drug resistance of tumor cells and exhibit enhanced therapeutic effects for breast cancer. Last but not least, 37.3 g of polyphenol CSs was massively produced at one time with a yield of 74.6%, laying a solid foundation for the practical applications of reassembled nanomedicines. The present strategy leading to a general nanomedicines platform was concise and highly efficient for both hydrophilic and hydrophobic drugs, making a breakthrough for low loading dilemma of current nanomedicines, and would open up a new direction for the preparation of nanocarriers, nanocomposites, and nanomedicines from natural polyphenols.

Micro-/Nanomechanics Dependence of Biomimetic Matrices upon Collagen-Based Fibrillar Aggregation and Arrangement.

The mechanical and morphological cues of fibrillar extracellular matrices (ECMs) play vital roles in controlling the cellular behaviors. Understanding and regulating the correlation of the mechanics with morphologies, at the micro-/nanoscale are of great relevance to guide the growth and differentiation of stem or progenitor cells into the desired tissues. However, the investigations directed toward acquiring such a kind of correlation are very limited and far from satisfactory. Here, rheological and nanoindentation tests were employed to appraise the mechanical behaviors of biomimetic ECMs assembled from type I collagen solutions containing the equivalent content of alginate but with different molecular weights (MWs). An alginate-molecular-weight-dependent trend was found in the fibrillogenesis process and the fibril aggregation of these collagen-alginate (CA) matrices. The present study revealed that the viscoelasticity and nonlinear elasticity of the CA matrices relied upon their specific fibrillar architectures in which a heterogeneous structure formed with varying alginate MW, including the coexistence of small fibrils and larger fibrillar bundles. The correlation of the mechanical behaviors with the inhomogeneity in the fibrillar structures was further discussed in combination with those of Ca2+ ionically cross-linked CA matrices. This study not only presented the delicate mechanics of fibrillar ECM analogues but also showed that the introduction of affiliative matters such as polysaccharides (alginate with different MWs) is a simple and convenient strategy to achieve biomimetic hydrogels with tunable viscoelastic properties.

Alginate-Assisted Mineralization of Collagen by Collagen Reconstitution and Calcium Phosphate Formation.

The understanding of the mineralization of collagen for bone formation is a current key theme in bone tissue engineering and is of great relevance to the fabrication of novel biomimetic bone grafting materials. The noncollagenous proteins (NCPs) play a vital role in bone formation and are considered to be responsible for regulating intrafibrillar penetration of minerals into collagen fibrils by means of their abundant polyanionic domains. In this study, alginate, as a NCPs analogue, was introduced in the mineralization of collagen to mediate the collagen self-assembly with simultaneous hydroxyapatite (HA) synthesis. The biomimetic systems were based upon the self-assembly of collagen (Col) or collagen-alginate (CA) in the absence or presence of a varying content of HA. The alginate-mediated effects were found to include the lateral aggregation of small fibrils into the extremely large bundles and the assisted deposition of HA for a larger mineralized fibril. This alginate-assisted mineralization of collagen gave rise to an exquisite 3D mineralized architecture with enhanced mechanical property. The cell viability experiments showed the excellent proliferation and spreading morphologies of rat bone mesenchymal stem cells (MSCs) on the assembled products, and a higher expression of osteogenic differentiation related transcription factor was obtained in the alginate-assisted mineralization of collagen. This study indicated that the selection of an appropriate substance, e.g., alginate as an anionic polyelectrolyte with Ca-capturing property, could be a convenient, simple solution to achieve a mineralized collagen scaffold with the reinforced mechanical property for potential applications in bone regeneration.