Fabrication of dopamine modified polylactide-poly(ethylene glycol) scaffolds with adjustable properties

An artificialed protein corona coating the surface of magnetic nanoparicles:a simple and efficient method for label antibody

Background

Protein Corona (PC) of nanoparticles is a structure which composed of one or more layers of proteins adsorbed on the surface of nanomaterials, and the formation of PC is a universal process of spontaneous randomness. We take advantage of the formation principle of the PC, developed a simple and efficient method for label protein to nanoparticles.

Methods

The artificialed protein corona (APC) on the surface of nanoparticles was synthesized via the artificialed methods of desolvation aggregation and crosslinking with control.

Results

The dosage of precipitator and the ratio of protein to magnetic nanoparticles (MNPs)(particle size: 3 nm) were optimized, and the core-shell nanoparticles with narrow particle size (particle size: 10 nm) distribution were obtained. The MNPs with APC were characterized by transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). Additionally, a hemolysis test on prepared MNPs was conducted with APC. The presence of APC coating on the surface of MNPs showed an improving effect to reduce the cytotoxicity. Cellular toxicity of MNPs with APC was also investigated on HFF1 cell lines. And the cells survival in the presence of APC coated MNPs and display neither reduced metabolism nor cytostatic effect. The functional test of the MNPs with APC showed that proteins can be modified and labeled onto magnetic nanoparticles and retain their original activity.

Conclusions

This marking method is gentle and effective. And the properties of the APC propose MNPs as a promising candidate for multifunctional biomedical applications.

Biological Response to a Novel Hybrid Polyoligomer: in vitro and in vivo Models

The aim of the study is to evaluate biocompatibility of a novel hybrid polyoligomer in in vitro and in vivo models.

Enwrapping Polydopamine on Doxorubicin-Loaded Lamellar Hydroxyapatite/Poly(lactic-co-glycolic acid) Composite Fibers for Inhibiting Bone Tumor Recurrence and Enhancing Bone Regeneration

Simultaneous prevention of bone tumor recurrence and promotion of repairing bone defects resulting from tumorectomy remain a challenge. Herein, we report a polydopamine (PDA)-coated composite scaffold consisting of doxorubicin (DOX)-loaded lamellar hydroxyapatite (LHAp) and poly(lactic-co-glycolic acid) (PLGA) in an attempt to reach dual functions of tumor inhibition and bone repair. The DOX was intercalated into LHAp, and the DOX-loaded LHAp was incorporated into PLGA solution to prepare a DOX-intercalated LHAp/PLGA (labeled as DH/PLGA) scaffold that was coated with PDA to obtain a PDA@DH/PLGA scaffold. The morphology, structure, wettability, mechanical properties, drug release, biocompatibility, and in vitro and in vivo bioactivities of the PDA@DH/PLGA scaffold were evaluated. It is found that PDA coating not only improves hydrophilicity and mechanical properties, but also leads to more sustainable drug release. More importantly, the PDA@DH/PLGA scaffold shows significantly inhibited growth of tumor cells initially and subsequent improved adhesion and proliferation of osteoblasts. In addition, the PDA coating improves the bioactivity of the DH/PLGA scaffold as suggested by the in vitro biomineralization. Further in vivo study demonstrates the improved bone growth around PDA@DH/PLGA over DH/PLGA after 20 days of drug release. The dual functional PDA@DH/PLGA scaffold shows great promise in the treatment of bone tumor.

Hydroxyapatite/silver electrospun fibers for anti-infection and osteoinduction

Bone implant materials cause the most common complication of bone infections in orthopedic surgery, resulting in implant failure. Antibiotic treatment of bone infections leads to problems such as bacterial resistance and reduced osteogenic capacity. In this study, dopamine (DA) was self-polymerized on the surface of Polylactic acid (PLLA)/Hydroxyapatite (HA) nanowire composite fibers to form an adhesive polydopamine (PDA) membrane, and a stable silver-nanoparticles (Ag-NPs) coating layer was constructed on it by electrochemically driven Ag⁺ coordination and chelation through Polypyrrole (PPy) mediation, achieving steady and slow release of Ag-NPs. With optimized DA soaking time of 24 h and soaking concentration of 0.5 g·L^-1, nanoparticles were uniformly distributed on PLLA/HA/PDA/PPy/Ag composite fibers and the hydrophilicity of the composite fibers was well-behaved. Besides, the composite fibers possessed good physiological stability and 100% antibacterial rate against Escherichia coli (E. coli) as well as Staphylococcus aureus (S. aureus). In addition, the composite fibers had promoted apatite nucleation and growth on surface and good cytocompatibility with osteoblasts, indicating ability of inducing osteogenic differentiation. In summary, a multi-functional PLLA/HA/PDA/PPy/Ag composite fiber with long-term antibacterial property, bioactivity and osteoinductivity was successfully constructed by electrospinning and electrochemical deposition.

Adenosine-Functionalized Biodegradable PLA-b-PEG Nanoparticles Ameliorate Osteoarthritis in Rats

Short biologic half-lives limit the therapeutic utility of many small molecules. One approach to extending the half-life of pharmacologically active small molecules is conjugation to less degradable nanoparticles; here we report the synthesis and activity of six targeted polymeric (PEG-b-PLA) nanoparticles for use as adenosine receptor agonists. Using click chemistry, PLA-b-PEG400-N₃ and PLA-b-PEG2000 block copolymers were bound to adenosine at the 3′,4′-OH, 5′-OH, and 6-NH₂ positions with an acetylene group. Activity of the conjugates as adenosine receptor ligands was tested by their capacity to stimulate cAMP increases in RAW264.7 murine macrophage cells. Only adenosine-conjugated nanoparticles (A-3′,4′-OH-TPN2), in which PEG2000 was bound to adenosine on the 3′,4′ hydroxyl groups, stimulated cAMP increases and these increases were blocked by selective antagonists of both adenosine A2A and A2B receptors, consistent with ligation of these receptors. Adenosine nanoparticles were tested in vivo in a rat model of post-traumatic osteoarthritis; intra-articular injection of adenosine nanoparticles prevented the development of osteoarthritis in this model. These studies suggest that attachment of adenosine to biodegradable nanoparticles provides a novel approach to achieving prolonged therapeutic effects.

Preparation and properties of dopamine-modified alginate/chitosan-hydroxyapatite scaffolds with gradient structure for bone tissue engineering

Three-dimensional (3D) homogenous scaffolds composed of natural biopolymers have been reported as superior candidates for bone tissue engineering. There are still remaining challenges in fabricating the functional scaffolds with gradient structures to similar with natural bone tissues, as well as high mechanical properties and excellent affinity to surround tissues. Herein, inspired by the natural bone structure, a gradient-structural scaffold composed of functional biopolymers was designed to provide an optimized 3D environment for promoting cell growth. To increase the interactions among the scaffolds, dopamine (DA) was employed to modify alginate (Alg) and needle-like nano-hydroxyapatite (HA) was prepared with quaternized chitosan as template. The obtained dopamine-modified alginate (Alg-DA) and quaternized chitosan-templated hydroxyapatite (QCHA) were then used to fabricate the porous gradient scaffold by "iterative layering" freeze-drying technique with further crosslinking by calcium ions (Ca²⁺ ). The as-prepared Alg-DA/QCHA gradient scaffolds were possessed seamlessly integrated layer structures and high levels of porosity at around 77.5%. Moreover, the scaffolds showed higher compression modules (1.7 MPa) than many other biopolyermic scaffolds. The gradient scaffolds showed appropriate degradation rate to satisfy with the time of the bone regeneration. Both human chondrocytes and fibroblasts could adhesive and growth well on the scaffolds in vitro. Furthermore, an excellent osteogenetic activity of the gradient scaffold can effectively promote the regeneration of the bone tissue and accelerate the repair of the bone defects in vivo, compared with that of the scaffold with the homogenous structure. The novel multilayered scaffold with gradient structure provided an interesting option for bone tissue engineering. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 1615-1627, 2019.