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Nuclear localized signals (NLS) capable of recognition by nuclear transport proteins can aid the nuclear translocation of the payloads. In this report, NLS peptide PKKKRKV (PV7, one of the primary NLS peptides) was introduced into GO-PEI (10 kDa)/DNA binary complexes to engineer a nuclei localized gene delivery system, based on electrostatic and hydrogen-bonded interactions. To assess the functional mechanism of NLS peptides in the GO-PEI system, the PV7 was introduced via three different routes, including post-addition after the formation of a GO-PEI/DNA binary, simultaneous addition with GO-PEI, pDNA, and prior-addition into the cell culture before treatment with GO-PEI/DNA complexes. In vitro transfection investigations revealed that the ternary composites engineered by the simultaneous route (that is the second route referred to above) exhibit a higher transfection efficiency in comparison with GO-PEI 10 kDa or PEI 10 kDa and are even comparable with PEI 25 kDa with optimized parameters. The study on the intracellular uptake of Cy3 labeled pDNA indicated that the addition of PV7 could effectively assist the GO-PEI to deliver plasmid DNA directly into the nucleus without obvious aggregations. With the improved capability of gene delivery, however, the cytotoxicity of GO-PEI was much lower than PEI 10 kDa and PEI 25 kDa against both HeLa cells and 293 T cells. Therefore, the PV7 conjugated GO-PEI system compromised the contradiction between the cytotoxicity and transfection efficiency, which could be an alternative strategy for a nuclear targeted gene delivery vehicle.

Presented in this article is the synthesis of a new class of block copolymer, poly(ethylene oxide)-blockpoly(tert-butyl acrylate-stat-acrylic acid) [PEO-b-P(AA-stat-tBA)], which can self-assemble into polymer vesicles with tuneable sizes at various conditions. The biocompatible and hydrophilic PEO chains form the vesicle coronas, while the PAA-stat-PtBA chains form the membrane. Superparamagnetic iron oxide nanoparticles (SPIONs) were generated in situ within the membrane of the polymer vesicles by nanoprecipitation. 1 H NMR, GPC, DLS, TGA, VSM and TEM were employed to characterize the structure and properties of the block copolymer, polymer vesicles and Fe 3 O 4 -decorated magnetic polymer vesicles. The water-dispersible, biocompatible, drug deliverable and superparamagnetic polymer vesicles exhibited excellent colloidal stability at a range of pH conditions and very high T 2 relaxivity, demonstrating ultra-sensitivity for magnetic resonance imaging and promising potential applications in nanomedicine.

One of the major challenges in vaccine design has been the over dependence on incorporation of abundant adjuvants, which in fact is in violation of the "minimalist" principle. In the present study, a compact nanovaccine derived from a near whole antigen (up to 97 wt %) was developed. The nanovaccine structure was stabilized by free cysteines within each antigen (ovalbumin, OVA), which were tempospatially exposed and heat-driven to form an extensive intermolecular disulfide network. This process enables the engineering of a nanovaccine upon integration of the danger signal (CpG-SH) into the network during the synthetic process. The 50 nm-sized nanovaccine was developed comprising approximately 500 antigen molecules per nanoparticle. The nanovaccine prophylactically protected 70% of mice from tumorigenesis (0% for the control group) in murine B16-OVA melanoma. Significant tumor inhibition was achieved by strongly nanovaccine-induced cytotoxic T lymphocytes. This strategy can be adapted for the future design of vaccine for a minimalist composition in clinical settings.

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Highly porous scaffolds of poly(lactide-co-glycolide) (PLGA) were prepared by solution-casting/salt-leaching method. The in vitro degradation behavior of PLGA scaffold was investigated by measuring the change of normalized weight, water absorption, pH, and molecular weight during degradation period. Mesenchymal stem cells (MSCs) were seeded and cultured in three-dimensional PLGA scaffolds to fabricate in vitro tissue engineering bone, which was investigated by cell morphology, cell number and deposition of mineralized matrix. The proliferation of seeded MSCs and their differentiated function were demonstrated by experimental results. To compare the reconstructive functions of different groups, mandibular defect repair of rabbit was made with PLGA/MSCs tissue engineering bone, control PLGA scaffold, and blank group without scaffold. Histopathologic methods were used to estimate the reconstructive functions. The result suggests that it is feasible to regenerate bone tissue in vitro using PLGA foams with pore size ranging from 100-250 microm as scaffolding for the transplantation of MSCs, and the PLGA/MSCs tissue engineering bone can greatly promote cell growth and have better healing functions for mandibular defect repair. The defect can be completely recuperated after 3 months with PLGA/MSCs tissue engineering bone, and the contrastive experiments show that the defects could not be repaired with blank PLGA scaffold. PLGA/MSCs tissue engineering bone has great potential as appropriate replacement for successful repair of bone defect.

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Biodegradable polymer/bioceramic composite scaffolds can overcome the limitations of conventional ceramic bone substitutes such as brittleness and difficulty in shaping. However, conventional methods for fabricating polymer/bioceramic composite scaffolds often use organic solvents (e.g., the solvent casting and particulate leaching (SC/PL) method), which might be harmful to cells or tissues. In this study, Poly (D,L-lactide)/nano-hydroxyapatite (PDLLA/NHA) composites were prepared by in-situ polymerization, and highly porous scaffolds were fabricated using a novel method, supercritical CO2/salt-leaching method (SC CO2/SL). The materials and scaffolds were investigated by scanning electronic microscopy (SEM), transmission electronic microscopy (TEM) and gel permeation chromatography (GPC). GPC showed that the molecular weight of composites decreased with increase of NHA content. However, the water absorption and compressive strength increased dramatically. The SEM micrographs showed that the scaffolds with pore size about 250 microm were obtained by controlling parameters of SC CO2/SL. The biocompatibility of PDLLA/NHA porous scaffolds were evaluated in vitro and in vivo. The evaluation on the cytotoxicity were carried out by cell relative growth rate (RGR) method and cell direct contact method. The cytotoxicity of these scaffolds was in grade I according to ISO 10993-1. There was no toxicosis and death cases observed in acute systemic toxicity test. And histological observation of the tissue response (1 and 9 weeks after the implantation) showed that there are still some slight inflammation responses.