JinRong Peng

In vivo biocompatibility and osteogenesis of electrospun poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone)/nano-hydroxyapatite composite scaffold.

A flexible and fibrous composite scaffold composed of poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) and 30 wt.% nano-hydroxyapatite (n-HA) was fabricated through electrospinning. In the present study, we investigated its in vitro and in vivo performance by means of hydrolytic degradation, muscle pouch implantation, as well as repair the calvarial defects in New Zealand white rabbits. The results demonstrated that the degradable scaffold held good biocompatibility. Qualitative analysis of bone regeneration process was performed by radiological examination and histological analysis. The results indicated that new bone formed originally from the margin of host bone, and then grew toward the center of defects. Moreover, the quantitative determination of newly formed bone was performed using statistical analysis of histological sections at predetermined time points. At 20th week, the defects of treatment group were covered with the new solid cortical bone. In comparison, the control group was filled with a large amount of cancelous bone and bone marrow. It suggested that the composite scaffold had better activity of guided bone regeneration than that of self-healing. So the electrospun PCEC/n-HA fibrous scaffold had the great potential application in bone tissue engineering.

Combined Cancer Photothermal-Chemotherapy Based on Doxorubicin/Gold Nanorod-Loaded Polymersomes

Gold nanorods (GNRs) are well known in photothermal therapy based on near-infrared (NIR) laser absorption of the longitudinal plasmon band. Herein, we developed an effective stimulus system -- GNRs and doxorubicin co-loaded polymersomes (P-GNRs-DOX) -- to facilitate co-therapy of photothermal and chemotherapy. DOX can be triggered to release once the polymersomes are corrupted under local hyperthermic condition of GNRs induced by NIR laser irradiation. Also, the cytotoxicity of GNRs caused by the residual cetyltrimethylacmmonium bromide (CTAB) was reduced by shielding the polymersomes. The GNRs-loaded polymersomes (P-GNRs) can be efficiently taken up by the tumor cells. The distribution of the nanomaterial was imaged by IR-820 and quantitatively analyzed by ICP-AES. We studied the ablation of tumor cells in vitro and in vivo, and found that co-therapy offers significantly improved therapeutic efficacy (tumors were eliminated without regrowth.) compared with chemotherapy or photothermal therapy alone. By TUNEL immunofluorescent staining of tumors after NIR laser irradiation, we found that the co-therapy showed more apoptotic tumor cells than the other groups. Furthermore, the toxicity study by pathologic examination of the heart tissues demonstrated a lower systematic toxicity of P-GNRs-DOX than free DOX. Thus, the chemo-photothermal treatment based on polymersomes loaded with DOX and GNRs is a useful strategy for maximizing the therapeutic efficacy and minimizing the dosage-related side effects in the treatment of solid tumors.

Mesoporous magnetic gold "nanoclusters" as theranostic carrier for chemo-photothermal co-therapy of breast cancer.

Photothermal therapy (PTT) is proved to be an efficient manner for superficial tumor therapy in preclinical studying. The tumor suppression of chemotherapy can be enhanced by combining with PTT. In this study, we reported a mesoporous magnetic gold “nanoclusters” (MMGNCs) structure as theranostic carrier for chemo-photothermal co-therapy. MMGNCs were successfully prepared and they exhibited efficient photo-thermal effect for PTT. The mesoporous structure provided MMGNCs with high drug loading capacity. By in vitro cytotoxicity testing, we revealed that the combination of PTT and chemotherapy could cause more damage than chemotherapy or PTT did alone. By topically targeting mediated by the extra-magnetic field (MF), MMGNCs can be targeted to the tumor site efficiently. In vivo chemo-photothermal co-therapy of 4T1 breast cancer, under the combinational treatments of chemo-photothermal co-therapy and extra-MF targeting, the tumor growth has been efficiently inhibited, and the pulmonary and mediastinal metastasis have also been prevented. The survival of the cancer bearing mice was prolonged. The bio-imaging applications of this system and the mechanism of the metastasis prevention are ongoing.

Label-free alpha fetoprotein immunosensor established by the facile synthesis of a palladium-graphene nanocomposite.

In this study, we established a sensitive label-free immunosensor by palladium-reduced graphene oxide (Pd-rGO), which was prepared by one-pot synthesis under the reduction of extra-injected CO gas. The Pd-rGO nanocomposite structure has been confirmed by TEM, SEM, X-ray diffraction, and UV-vis spectroscopy. The Pd-rGO nanocomposite exhibited excellent stability in aqueous dispersion. The Pd-rGO-based label-free electrochemical immunosensor was used for detection of the hepatocellular carcinoma (HCC) biomarker alpha fetoprotein (AFP). The immunosensor determination was based on the fact that due to the formation of antigen-antibody immunocomplex, the decreased response amperometric currents of H2O2 were directly proportional to the concentrations of AFP. The limit of detection of this immunosensor for AFP detection is 5 pg/mL, and is linear from 0.01 to 12 ng/mL. The proposed immunosensor has been used to determine AFP in clinical serum samples with satisfactory results. This suggests the sensor may have great potential utility in the clinic.

Preparation of poly(ethylene glycol)/polylactide hybrid fibrous scaffolds for bone tissue engineering

Polylactide (PLA) electrospun fibers have been reported as a scaffold for bone tissue engineering application, however, the great hydrophobicity limits its broad application. In this study, the hybrid amphiphilic poly(ethylene glycol) (PEG)/hydrophobic PLA fibrous scaffolds exhibited improved morphology with regular and continuous fibers compared to corresponding blank PLA fiber mats. The prepared PEG/PLA fibrous scaffolds favored mesenchymal stem cell (MSC) attachment and proliferation by providing an interconnected porous extracellular environment. Meanwhile, MSCs can penetrate into the fibrous scaffold through the interstitial pores and integrate well with the surrounding fibers, which is very important for favorable application in tissue engineering. More importantly, the electrospun hybrid PEG/PLA fibrous scaffolds can enhance MSCs to differentiate into bone-associated cells by comprehensively evaluating the representative markers of the osteogenic procedure with messenger ribonucleic acid quantitation and protein analysis. MSCs on the PEG/PLA fibrous scaffolds presented better differentiation potential with higher messenger ribonucleic acid expression of the earliest osteogenic marker Cbfa-1 and mid-stage osteogenic marker Col I. The significantly higher alkaline phosphatase activity of the PEG/PLA fibrous scaffolds indicated that these can enhance the differentiation of MSCs into osteoblast-like cells. Furthermore, the higher messenger ribonucleic acid level of the late osteogenic differentiation markers OCN (osteocalcin) and OPN (osteopontin), accompanied by the positive Alizarin red S staining, showed better maturation of osteogenic induction on the PEG/PLA fibrous scaffolds at the mineralization stage of differentiation. After transplantation into the thigh muscle pouches of rats, and evaluating the inflammatory cells surrounding the scaffolds and the physiological characteristics of the surrounding tissues, the PEG/PLA scaffolds presented good biocompatibility. Based on the good cellular response and excellent osteogenic potential in vitro, as well as the biocompatibility with the surrounding tissues in vivo, the electrospun PEG/PLA fibrous scaffolds could be one of the most promising candidates in bone tissue engineering.

“One-for-All”-Type, Biodegradable Prussian Blue/Manganese Dioxide Hybrid Nanocrystal for Trimodal Imaging-Guided Photothermal Therapy and Oxygen Regulation of Breast Cancer

Multimodal imaging-guided diagnosis and therapy has been highlighted in the area of theranostic nanomaterials. To provide more suitable theranostic candidates, Prussian blue (PB)/manganese dioxide (MnO2) hybrid nanoparticles (PBMn) smaller than 50 nm are prepared by a one-pot method. MnO2, which is reduced from KMnO4, not only controls the particle size, the optical properties, and the transverse relaxation rate (r2) of PB but also enhances the catalysis efficacy of PB to H2O2 for oxygen generation. PBMn can serve as a photoacoustic imaging (PAI) and longitudinal relaxation (T1) mode magnetic resonance imaging contrast agent (14 times and 1.8 times of the saline-treated group, respectively). Injection of PBMn can regulate the oxygen partial pressure of the tumor tissue from 2.1 ± 0.2 to 9.3 ± 0.4 kPa and rearrange the ratio of oxygenated hemoglobin and deoxygenate hemoglobin inside the tumor, which favor the enhancement of the diamagnetic T2-weighted imaging (T2WI) signal intensity (two times that of the saline-treated group). Furthermore, PBMn-mediated PTT can efficiently inhibit the growth of the MCF-7 tumor in vitro and in vivo. PBMn can serve as a PAI/T1/T2 trimodal contrast agent and in imaging-guided PTT, as well as in the oxygen regulation of the exografted breast cancer.

A Novel MPEG-PDLLA-PLL Copolymer for Docetaxel Delivery in Breast Cancer Therapy

Satisfactory drug loading capacity and stability are the two main factors that determine the anti-cancer performance. In general, the stability of the micelles is reduced when the drug loading (DL) is increased. Therefore, it was a challenge to have high drug loading capacity and good stability. In this study, we introduced a hydrophilic poly (L-Lysine) (PLL) segment with different molecular-weights into the monomethoxy poly (ethylene glycol)-poly (D, L-lactide) (MPEG-PDLLA) block copolymer to obtain a series of novel triblock MPEG-PDLLA-PLL copolymers. We found that the micelles formed by a specific MPEG2k-PDLLA4k-PLL1k copolymer could encapsulate docetaxel (DTX) with a satisfactory loading capacity of up to 20% (w/w) via the thin film hydration method, while the stability of drug loaded micellar formulation was still as good as that of micelles formed by MPEG2k-PDLLA1.7k with drug loading of 5% (w/w). The results from computer simulation study showed that compared with MPEG2k-PDLLA1.7k, the molecular chain of MPEG2k-PDLLA4k-PLL1k could form a more compact funnel-shaped structure when interacted with DTX. This structure favored keeping DTX encapsulated in the copolymer molecules, which improved the DL and stability of the nano-formulations. The in vitro and in vivo evaluation showed that the DTX loaded MPEG2k-PDLLA4k-PLL1k (DTX/MPEG2k-PDLLA4k-PLL1k) micelles exhibited more efficiency in tumor cell growth inhibition. In conclusion, the MPEG2k-PDLLA4k-PLL1k micelles were much more suitable than MPEG2k-PDLLA1.7k for DTX delivery, and then the novel nano-formulations showed better anti-tumor efficacy in breast cancer therapy.

Injectable Alginate Hydrogel Cross-Linked by Calcium Gluconate-Loaded Porous Microspheres for Cartilage Tissue Engineering

A great interest has been shown in the injectable scaffolds for cartilage tissue regeneration because it can fill irregularly shaped defects easily through minimally invasive surgical treatments. Herein, we developed a new injectable three-dimensional (3D) alginate hydrogel loaded with biodegradable porous poly(ε-caprolactone)–b-poly(ethylene glycol)–b-poly(ε-caprolactone) microspheres (MPs/Alg) as the calcium gluconate container to cross-link alginate. Suspensions of chondrocytes/alginate and porous microspheres turned into a gel because of the release of calcium gluconate; thus, the injectable composite hydrogels give a 3D scaffold to fit the defects perfectly and integrate the extracellular-matrix-mimicking architecture to efficiently accommodate cartilage cells in situ. Tissue repair in a full-thickness cartilage defect model was controlled at 6, 12, and 18 weeks after the implant by micro-CT and immunohistochemistry to evaluate the healing status. The defect in the MPs/Alg+ cells group achieved an almost complete repair at 18 weeks, and the repaired chondrocytes regained a normal tissue structure. Moreover, the MPs/Alg+ cells-treated group increased the quality of tissue formed, including the accumulated glycosaminoglycan and the uniformly deposited type II collagen. The results point out the promising application of the injectable MPs/Alg-chondrocytes system for cartilage tissue engineering.

Synthesis, characterization and drug loading property of Monomethoxy-Poly(ethylene glycol)-Poly(ε-caprolactone)-Poly(D,L-lactide) (MPEG-PCLA) copolymers.

Amphiphilic block copolymers have attracted a great deal of attention in drug delivery systems. In this work, a series of monomethoxy-poly (ethylene glycol)-poly (ε-caprolactone-co-D,L-lactide) (MPEG-PCLA) copolymers with variable composition of poly (ε-caprolactone) (PCL) and poly (D,L-lactide) (PDLLA) were prepared via ring-opening copolymerization of ε-CL and D,L-LA in the presence of MPEG and stannous octoate. The structure and molecular weight were characterized by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The crystallinity, hydrophilicity, thermal stability and hydrolytic degradation behavior were investigated in detail, respectively. The results showed that the prepared amphiphilic MPEG-PCLA copolymers have adjustable properties by altering the composition of PCLA, which make it convenient for clinical applications. Besides, the drug loading properties were also studied. Docetaxel (DTX) could be entrapped in MPEG-PCLA micelles with high loading capacity and encapsulation efficiency. And all lyophilized DTX-loaded MPEG-PCLA micelles except MPEG-PCL micelles were readily re-dissolved in normal saline at 25 °C. In addition, DTX-loaded MPEG-PCLA micelles showed a slightly enhanced antitumor activity compared with free DTX. Furthermore, DTX micelles exhibited a slower and sustained release behavior in vitro, and higher DTX concentration and longer retention time in vivo. The results suggested that the MPEG-PCLA copolymer with the adjustable ratio of PCL to PDLLA may be a promising drug delivery carrier for DTX.

Injectable and Thermosensitive Hydrogel and PDLLA Electrospun Nanofiber Membrane Composites for Guided Spinal Fusion

Spinal fusion is the classic treatment to achieve spinal stability for the treatment of the spinal disease. Generally, spinal fusion still has to combine a certain of bone matrix for promoting bone formation to achieve the desired fusion effect based on the surgery, including the traditional bone matrix, such as the autologous bone, allografts and xenografts. Nevertheless, some problems still existed such as the immunogenic problems, the secondary wound, and pathogenic transfer and so on. Here the injectable thermosensitive hydrogel could substitute to avoid the problems as a potential biological scaffold for tissue engineering. Once injected, they could fill in the irregular-shaped cavity and change to a gel state at physiological temperature. We wanted to design the collagen/n-HA/BMP-2@PCEC/PECE hydrogel composites based on previous work about collagen/n-HA/PECE hydrogel to exhibit better performance in guiding spinal fusion because of the addition of BMP-2@PCEC nanoparticles (PCEC, PCL-PEG-PCL). However, when the hydrogels were injected, one of the surfaces was in contact with the spine, but others were in contact with soft tissue like muscles and fascia. The release behavior was the same at the different surfaces, so the factors could be released into the soft tissue, and it may then be consumed or lead to ectopic bone formation. The hydrogel composites should be improved to adjust the direction of the releaser behavior. In consequence, we wrapped an electrostatic spinning nanofiber membrane possessing hydrophobicity around the hydrogels. In this study, we developed a system that the collagen/n-HA/BMP-2@PCEC/PECE hydrogels were wrapped with the hydrophobicity PDLLA electrospun nanofiber membrane, setting up a barrier between the hydrogels and the soft tissue. The system could exhibit biocompatibility, preventing the factors from escaping to keep their retention in the needed places of osteogenesis; the results demonstrated that it showed an excellent effect on spinal fusion.