Tianbin Ren

Preparation and Therapeutic Efficacy of Polysorbate-80-Coated Amphotericin B/PLA-b-PEG Nanoparticles

Amphotericin B (AmB)/poly(lactic acid)-b-poly(ethylene glycol) (PLA-b-PEG) nanoparticles coated with polysorbate 80 (Tween-80) were prepared by nanoprecipitation for transport across the blood–brain barrier (BBB). The effects of Tween-80 on the size and distribution, entrapment efficiency and release behavior of AmB/PLA-b-PEG nanoparticles were investigated. Furthermore, the brain targeting and curative effect of coated nanoparticles were also investigated. The entrapment efficiency was significantly enhanced when nanoparticles were coated with Tween-80. The prepared nanoparticles were spherical with homogeneous distribution. Drug concentration in mice brain was greatly enhanced, which indicated that the coated nanoparticles could get across the BBB. Meanwhile, the AmB/PLA-b-PEG nanoparticles are able to reduce the toxicity of AmB to liver, kidney and blood system with improved therapeutic effect.

Repair of mandibular defects using MSCs-seeded biodegradable polyester porous scaffolds

PLLA, PLA-PEG and PLGA porous scaffolds with pore size ranging from 100 to 250 μm and porosity over 85% were fabricated by a solution-casting/salt-leaching method. The porous structure and porosity of the scaffold were mainly dependent on volume fraction and size of the porogens of NaCl particles. The effects of the polymeric materials on the cell culture behavior and bone formation in vitro in their scaffolds were studied. In vitro cell culture in the scaffolds of the three polymers demonstrated that mesenchymal stem cells (MSCs) had a good adhesion and spread. The composite matrixes cultured for several days possessed preliminary functions of tissue-engineering bone, with signs of the calcium knur formation and the expression of osteocalcin and collagen I in mRNA, especially that of PLA-PEG and PLGA. These cell-loaded porous scaffolds showed effective repair of mandibular defect of rabbits in vivo. Contrastive experiments demonstrated that the MSCs/PLGA scaffold owned better ability facilitating for the MSCs proliferation, differentiation and defect repair. These composite scaffolds can be a potential effective tool for treating mandibular and other bone defects.

Bone marrow stromal cells cultured on poly (lactide-co-glycolide)/nano-hydroxyapatite composites with chemical immobilization of Arg-Gly-Asp peptide and preliminary bone regeneration of mandibular defect thereof

Polyethyleneimine (PEI) was used to create active groups on the poly (lactide-co-glycolide)/nano-hydroxyapatite (PLGA/NHA) surface and Arg-Gly-Asp (RGD) was grafted on the active groups and novel PLGA/NHA 2-D membranes and 3D scaffolds modified with RGD were obtained. X-ray photoelectron spectrum (XPS) results show that sulfur displays only on the modified surface. The RGD-modified PLGA/NHA materials also have much lower static water contact angle and much higher water-absorption ability, which shows that after chemical treatment, the modified materials show better hydrophilic properties. Atomic force microscope (AFM) shows that after surface modification, the surface morphology of PLGA is greatly changed. All these results indicate that RGD peptide has successfully grafted on the surface of PLGA. Rabbit bone marrow stromal cells (MSCs) were seeded in the 2D membranes and 3D scaffolds materials. The influences of the RGD on the cell attachment, growth and differentiation, and proliferation on the different materials were studied. The modified scaffolds were implanted into rabbits to observe preliminary application in regeneration of mandibular defect. The PLGA/NHA-RGD presents better results in bone regeneration in rabbit mandibular defect.

pH-responsive amphiphilic H-shaped supramolecular copolymer via the inclusion complexation between β - cyclodextrin and adamantane

AbstractpH-responsive amphiphilic H-shaped copolymer was prepared by the supramolecular self-assembly between β-cyclodextrin-graft-poly(2-(N,N-diethylamino)ethyl methacrylate) (β-CD-(PDEAEMA)2) and bi-adamantyl terminated poly(ε-caprolactone) (Ad-PCL-Ad). β-CD-(PDEAEMA)2 was synthesized by click reaction of alkynyl-modified β-CD with azide PDEAEMA (PDEAEMA-N3). Ad-PCL-Ad was synthesized by the DCC reaction of bi-hydroxyl terminated PCL (HO-PCL-OH) with adamantaneacetic acid. The supramolecular copolymer can self-assemble into micelles in water at room temperature. The micellization and pH-responsivity of the amphiphilic copolymer solution were investigated by transmittance, dynamic light scattering spectrophotometer, and transmission electron microscopy in water. Investigation shows that the micelles’ sizes can be adjusted through the alteration of the pH values of solutions and the supramolecular copolymer will have the potential applications in biomedical field.

Electrospun poly(L-lactide-co-ε-caprolactone)/polyethylene oxide/hydroxyapaite nanofibrous membrane for guided bone regeneration

A series of poly(L-lactide-co-e-caprolactone)/polyethylene oxide/hydroxyapaite (PLCL/PEO/HA) composite fibrous membranes were prepared by elecrospinning technology for guided bone regeneration. The morphology, water permeability and mechanical properties of the membranes were investigated. The HA nanocrystals can be well distributed in the PLCL/PEO matrix. And the diameter of composite nanofiber is larger than that of pure PLCL. The fibers with uniform size and large diameter were obtained when the contents of PEO and HA were 0.4% and 0.03%, respectively. In this condition, the obtained membrane presents the best water permeability. Furthermore, the nanofibrous membrane with largest tensile strength was obtained when the contents of PEO and HA were 0.5% and 0.03%, respectively.