AbstractConducting polymers have shown appealing performances as sensing materials in various smart sensors such as gas, chemical and biological sensors, owing to their unique physical and electrical properties. This study reports a novel development for the fabrication of visual-aided smart thermal (VAST) sensors. The sensors are based on conducting polymers, temperature-sensitive resin, and liquid crystal molecules via direct scrawling and in situ solventless polymerization. In the VAST sensor, the thermochromism resins and liquid crystals form a visual-aided system with the real-time early warning function and the conducting polymers provide an ultrahigh resolution by the measure of the change of resistivity. Additionally, these VAST sensors also hold the advantages of low cost, using simple tools, high stability, excellent adaptability to arbitrary substrates, wide application fields, and facile large-scale fabrication. These properties are in favor of fabricating smart thermal sensors to satisfy the practical demands, such as the demonstrated temperature detecting system (especially flexible devices with nonplanar surface), thermodefect diagnostic system, smart battery monitoring system, and other environment monitoring.

•A surface with high surface potential is constructed on bone implant.•The high potential surface mediates BMSCs to express distinct NOS level.•The high potential surface can induce new bone growth.•An excessively high surface potential produces substantial immunomodulatory effects.Despite the effects on physiology of bone marrow mesenchymal stem cells (BMSCs) and bone tissue, biological signal communication between bone implants and them is seldom employed as a guidance to create an osteo-inductive interface. Herein, the positively-charged surface is constructed on bone implant from the perspective of mediation of nitric oxide synthase (NOS) expression to signal BMSCs osteo-differentiation. In vitro and in vivo results indicate that the proper surface potential on the positively-charged surface affects NOS to express a high level of inducible nitric oxide synthase (iNOS) in three NOS isoforms of the contacted BMSCs, upregulates their osteogenetic expression, and ultimately foster new bone growth. However, an excessively high surface potential produces substantial immunomodulatory effects thereby offsetting the aforementioned advantages. This study demonstrates that fine-tuning of the positively-charged surface and proper utilization of the communication between NOS and bone implants promote bone formation.The communication between nitric oxide synthase (NOS) and bone implants is firstly employed as a guidance to create an osteo-inductive interface on bone implant. This study provides clear evidence that properly positively-charged surface promotes bone formation by mediating the direct communication with NOS.

Because of the complex plasma reactions and chemical structures of polymers, it is difficult to construct nitrogen functionalities controllably by plasma technology to attain the desirable biological outcome and hence, their effects on bone cells are sometimes ambiguous and even contradictory. In this study, argon plasma treatment is utilized to convert complex molecular chains into a pyrolytic carbon structure which possesses excellent cytocompatibility. The pyrolytic carbon then serves as a platform to prepare the desired nitrogen functionalities by nitrogen and hydrogen plasma immersion ion implantation. Primary, secondary, and tertiary amine groups can be produced selectively thus minimizing the chemical complexity and creation of multiple types of nitrogen functional groups that are often obtained by other fabrication methods. As a result of the excellent control of the nitrogen functionalities rendered by this plasma technique, the effects of individual nitrogen functionalities on the cytocompatibility and upregulation of bone marrow-derived mesenchymal stem cell (BMSC) osteogenesis can be investigated systematically. The tertiary amine functionalities exhibit the optimal efficiency pertaining to the modulation of the biological response, enhancement of osteogenesis related gene/protein expression, and calcification of the contacted BMSCs. Our results demonstrate that simple plasma technology can be conveniently employed to create the desirable nitrogen functionalities on orthopedic polymers to facilitate osseointegration and mitigate foreign body reactions.

To improve the tensile properties and degradability of poly(butylene succinate) (PBS) for biomedical usage, biodegradable polymer blends have been developed. A series of PBS and poly(lactic acid) (PLA) blends were prepared, and their degradation behaviors in simulated body fluid for 16 months were investigated based on morphology, tensile test, weight analysis, and molecular weight. The results showed that the incorporation of PLA into PBS increased the initial tensile strength to some extent, and the blends lost their tensile properties earlier than their parent polymers with the proceeding of hydrolysis. Both blends and parent polymers went through a plateau and subsequent rise stage in mass loss and water absorption, but the blends hydrolyzed faster than the parent polymers. The molecular weight variations also demonstrated faster hydrolysis of the blends. Moreover, both blends and their parent polymers underwent a slow-to-fast transition in their hydrolysis rates. When the Mn of PBS and PLA reached 4.0 × 104 and 9.0 × 104, the hydrolysis of parent polymers and blends began to accelerate, which is the start of auto-acceleration. The blends hydrolyzed faster in both stages. The interface between the components initiated accelerating hydrolysis in the first stage, and the reciprocal auto-acceleration effect resulted in faster hydrolysis of the blends in the second stage.

Poly(butylene succinate) (PBS)/graphene oxide (GO) nanocomposites were facilely prepared via in situ polymerization. The properties of the nanocomposites were studied using FTIR, XRD, and 1H NMR, and the state of dispersion of GO in the PBS matrix was examined by SEM. The crystallization and melting behavior of the PBS matrix in the presence of dispersed GO nanosheets have been studied by DSC and polarized optical microscopy. Through the mechnical testing machine and DMA, PBS/GO nanocomposites with 3% GO have shown a 43% increase in tensile strength and a 45% improvement in storage modulus. This high performance of the nanocomposites is mainly attributed to the high strength of graphene oxide combined with the strong interfacial interactions in the uniformly dispersed PBS/GO nanocomposites.

Because of the complex plasma reactions and chemical structures of polymers, it is difficult to construct nitrogen functionalities controllably by plasma technology to attain the desirable biological outcome and hence, their effects on bone cells are sometimes ambiguous and even contradictory. In this study, argon plasma treatment is utilized to convert complex molecular chains into a pyrolytic carbon structure which possesses excellent cytocompatibility. The pyrolytic carbon then serves as a platform to prepare the desired nitrogen functionalities by nitrogen and hydrogen plasma immersion ion implantation. Primary, secondary, and tertiary amine groups can be produced selectively thus minimizing the chemical complexity and creation of multiple types of nitrogen functional groups that are often obtained by other fabrication methods. As a result of the excellent control of the nitrogen functionalities rendered by this plasma technique, the effects of individual nitrogen functionalities on the cytocompatibility and upregulation of bone marrow-derived mesenchymal stem cell (BMSC) osteogenesis can be investigated systematically. The tertiary amine functionalities exhibit the optimal efficiency pertaining to the modulation of the biological response, enhancement of osteogenesis related gene/protein expression, and calcification of the contacted BMSCs. Our results demonstrate that simple plasma technology can be conveniently employed to create the desirable nitrogen functionalities on orthopedic polymers to facilitate osseointegration and mitigate foreign body reactions.