Dopamine induced multiple bonding in hyaluronic acid network to construct particle-free conductive hydrogel for reliable electro-biosensing.

Conductive hydrogel (CH) as flexible electrophysiology interface has become the new trend of bioelectronics, but still challenging in synergizing the biocompatibility, mechanics and comprehensive electrical performance. Hyaluronic acid (HA), featured with abundant active sites for personalized-modification and well-known biocompatibility, is one of the alterative candidates. The obstacle lies in the unstable conductivity from the ionic conduction, and the electronic conduction by embedding conductive nanoparticles (NPs) is likely to result in inhomogeneous CH with poor stretchability and discontinuous conductive network. Herein, inspired by catechol chemistry, dopamine (DA)-modified HA was homogeneously composited with DA-modified poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS, named PP), to produce particle-free conductive hydrogel (HA-DA-PP). The DA-introduced multiple bondings in HA network and PP molecules brought aqueous conductive PP into HA hydrogel to form a homogeneous crosslinking network, imparted the flexible stretchability. By accurately regulation, HA-DA-PP achieved high stretchability with large tensile deformation (over 470 %) in the category of natural polymer-based hydrogels. Moreover, the interaction between DA and PP (conformational transition and charge transfer) could effectively enhance the hydrogel's conductivity. Consequently, HA-DA-PP hydrogel showed high sensibility to human movement, epidermal and in vivo electrophysiological signals monitoring. Overall, DA-mediated multiple bonding is a powerful strategy for constructing CH with high performance for bioelectronics.

Preparation of electrospun PLGA-silk fibroin nanofibers-based nerve conduits and evaluation in vivo.

With advances in technical methodology, the grafting of biocompatible conduits may become a viable alternative for the reconstruction of nerve gaps. In this study, electrospinning was used to fabricate nerve conduits (NCs) from poly(L-lactide-coglycolide)-silk fibroin. Conduits or autograft nerves were employed to bridge 10 mm defects in the sciatic nerves of Sprague-Dawley rats. Six weeks after the operation, morphological and functional assessment showed that nerve conduits from PLGA-silk fibroin grafts promoted the regeneration of peripheral nerves. The effects were similar to those obtained using nerve autografts. This method offers a promising alternative to the use of nerve autografts.

[Histological and biomechanical study of repairing rabbit radius segmental bone defect with porous titanium].

OBJECTIVE: To investigate the therapeutic effects of porous titanium (Ti) on the recovery of rabbit radial bone defect. METHODS: Bone defects were artificially made in 30 New Zealand rabbits by resecting the 1 cm substantial osseo with periosteum of both radii. The left anterior limbs were implanted with porous titanium, while the right anterior limbs with porous hydroxyapatite (HA). The rabbits were sacrificed at three time points. Both the radii healing statuses were observed by histology and histomorphometry analyses by means of computer graphic processing at the end of 8, 12 and 24 weeks, and biomechanical analyses at the end of 12 and 24 weeks. RESULTS: The histology examination showed that mass newly formed bone had grown into most pores of both the specimens. Along with prolongation of times after operation, the ingrowths of bone cells and effects of bone remodeling in the research side were nearly the same as those in the control side at the end of 12 and 24 weeks. The interface between the new bone and implants showed tight contact in both the groups without an obvious fibrous tissue. The results of histomorphometrical analyses showed that a statistically significant difference was not obtained for % bone area (bone area/ gross implant) between both the groups (P>0.05).However, the results of maximum failure load for the Ti group and the HA group were (107.34±27.44) N and (93.42±21.18) N at the end of 12 weeks, (118.56±24.65) N and (102.15±23.37) N at the end of 24 weeks, respectively. Biomechanical properties of the Ti group was stronger than that of the HA group, however, a statistically significant difference was not obtained between both the groups (P=0.102). CONCLUSION: Porous titanium scaffold can promote the formation of new bone, which contributes to the healing of long tubular bone defect. The porous titanium can enhance the bone repairing effect on segmental bone defect nearly the same as porous hydroxyapatite .

PPy@MIL-100 Nanoparticles as a pH- and Near-IR-Irradiation-Responsive Drug Carrier for Simultaneous Photothermal Therapy and Chemotherapy of Cancer Cells.

A medical nanoplatform with small size, low cost, biocompatibility, good biodegradability, and, in particular, multifunctionality has attracted much attention in the exploration of novel therapeutic methodologies. As an emerging material of self-assembled porous structure, metal-organic frameworks (MOFs) have high expectations because of their special properties compared to traditional porous materials. Therefore, integration of MOFs and functional materials is leading to the creation of new multifunctional composites/hybrids. Photothermal therapy (PTT), using near-IR (NIR) laser-absorbing nanomaterials as PTT agents, has shown encouraging therapeutic effects to photothermally ablate tumors. However, the most of widely used PTT agents are inorganic materials and nonbiodegradable. Herein, uniform polypyrrole (PPy) nanoparticles (NPs) with good biodegradability were synthesized by a microemulsion method. The PPy NPs were further coated with the mesoporous iron-based MOF structure MIL-100 by interaction between PPy NPs and MIL-100 precursors at room temperature. As a multifunctional nanoplatform, an anticancer drug could easily be loaded into the mesopores of the MIL-100 shell. The PPy core, as an organic photothermal agent, is able to photothermally ablate cancer cells and improve the efficacy of chemotherapy under NIR irradiation. The composites showed an outstanding in vivo synergistic anticancer capacity. Our work could encourage further study in the construction of a synergetic system using MOFs and organic PTT agents.

Synthesis of hollow hydroxyapatite nanospheres by the control of nucleation and growth in a two phase system.

Hollow hydroxyapatite nanospheres were prepared by a two-phase approach by controlling nucleation and crystal growth processes. The cavities of hollow HA provide potential applications as new kinds of containers for carrying, filling in, or encapsulating other materials, thus constructing a multifunctional system with good biocompatibility.

Osteoinduction by Ca-P biomaterials implanted into the muscles of mice.

The osteoinduction of porous biphasic calcium phosphate ceramics (BCP) has been widely reported and documented, but little research has been performed on rodent animals, e.g., mice. In this study, we report osteoinduction in a mouse model. Thirty mice were divided into two groups. BCP materials (Sample A) and control ceramics (Sample B) were implanted into the leg muscle, respectively. Five mice in each group were killed at 15, 30, and 45 d after surgery. Sample A and Sample B were harvested and used for hematoxylin and eosin (HE) staining, immunohistochemistry (IHC) staining, and Alizarin Red S staining to check bone formation in the biomaterials. Histological analysis showed that no bone tissue was formed 15 d after implantation (0/5) in either of the two groups. Newly-formed bone tissues were observed in Sample A at 30 d (5/5) and 45 d (5/5) after implantation; the average amounts of newly-formed bone tissues were approximately 5.2% and 8.6%, respectively. However, we did not see any bone tissue in Sample B until 45 d after implantation. Bone-related molecular makers such as bone morphogenesis protein-2 (BMP-2), collagen type I, and osteopontin were detected by IHC staining in Sample A 30 d after implantation. In addition, the newly-formed bone was also confirmed by Alizarin Red S staining. Because this is the report of osteoinduction in the rodent animal on which all the biotechnologies were available, our results may contribute to further mechanism research.