In the research of flexible pressure sensors supported by three-dimensional skeleton structure, the combination of nanomaterials and skeleton structure is a difficult problem to be further solved. Herein, a piezoresistive sensor based on the graphene-PDMS @ sponge is prepared by fixing graphene on a sponge skeleton using PDMS. The as-prepared piezoresistive sensor exhibits high elasticity (strain up to 85%), high sensitivity (0.075 K Pa−1), a wide responding range (0–50 KPa) and high stability (2000 cycles pressure test). The piezoresistive sensor is used to detect blood pressure, heartbeat and human movements including finger bending, elbow movement and knee squatting, which shows good consistency and stability of the as-prepared sensor through the synergy of sponge, PDMS and graphene. The graphene-PDMS @ sponge sensor shows potential applications in medical testing and electronic skin.

Flexible pressure sensors based on capacitive induction have become a research hot-spot because of low energy consumption and excellent performance in recent years. In practical applications, a wide range of detection and low-cost mass-produced flexible pressure sensors are ideal. Herein, this paper presents a wide detection range capacitive pressure sensor based on a structured elastic electrode, which is low cost and can be mass-produced by a simple method of micropore PE tape molding. Test results show that the sensor's pressure detection range is 0-45 kPa. This is because the upper structure of the capacitive sensor is constantly changing when subjected to different external pressures, so that the contact area of the upper substrate of the sensor becomes larger and the distance between the upper and lower substrates becomes smaller. In addition, this capacitive pressure sensor exhibits low detection limit (<300 Pa), ultra-short response time (<50 ms) and high operational stability for repeated loading/unloading pressure cycles. The sensor owns excellent resolution and can distinguish language, and the sensor can be used to monitor pulse. Low-cost mass production and wide detection range of flexible capacitive pressure sensors lay the foundation for the development of electronic skin, contact inspection applications and wearable healthcare monitors.

Background: Previously, we demonstrated the therapeutic efficacy of a human papillomavirus (HPV) vaccine, including HPV16 E7 peptide and CpG oligodeoxynucleotides (CpG ODN), against small TC-1 grafted tumors. Here, we developed an HPV16 E7 peptide and CpG ODN vaccine delivered using liposomes modified with DC-targeting mannose, Lip E7/CpG, and determined its anti-tumor effects and influence on systemic immune responses and the tumor microenvironment (TME) in a mouse large TC-1 grafted tumor model. Methods: L-alpha-phosphatidyl choline (SPC), cholesterol (CHOL), 1,2-distearoyl-snglycero-3-phosphoethanolamine-N-[methoxy (polyethylene glycol-2000)] (DSPE-PEG-2000), 1,2-dioleoyl-3-trimethylammonium-propane chloride salt (DOTAP) and Mannose-PEG-DSPE, loaded with HPV16 E7 peptide and CpG ODN, were used to construct the Lip E7/CpG vaccine. The anti-tumor effects and potential mechanism of Lip E7/CpG were assessed by assays of tumor growth inhibition, immune cells, in vivo cytotoxic T lymphocyte (CTL) responses and cytokines, chemokines, CD31, Ki67 and p53 expression in the TME. In addition, toxicity of Lip E7/CpG to major organs was evaluated. Results: Lip E7/CpG had a diameter of 122.21±8.37 nm and remained stable at 4°C for 7 days. Co-delivery of HPV16 E7 peptide and CpG ODN by liposomes exerted potent antitumor effects in large (tumor volume ≥200mm 3) TC-1 grafted tumor-bearing mice with inhibition rates of 80% and 78% relative to the control and Free E7/CpG groups, respectively. Vaccination significantly increased numbers of CD4+ and CD8+ T cells, and IFN-γproducing cells in spleens and tumors and enhanced HPV-specific CTL responses, while reducing numbers of inhibitory cells including myeloid-derived suppressor cells and macrophages. Expression of cytokines and chemokines was altered and formation of tumor blood vessels was reduced in the Lip E7/CpG group, indicating possible modulation of the immunosuppressive TME to promote anti-tumor responses. Lip E7/CpG did not cause morphological changes in major organs. Conclusion: Lip E7/CpG induced anti-tumor effects by enhancing cellular immunity and improving tumor-associated immunosuppression. Mannose-modified liposomes are the promising vaccine delivery strategy for cancer immunotherapy.

In this study, inspired by the components of cartilage matrix, a photo-cross-linked extracellular matrix (ECM) bioink composed of modified proteins and polysaccharides was presented, including gelatin methacrylate, hyaluronic acid methacrylate, and chondroitin sulfate methacrylate. The systematic experiments were performed, including morphology, swelling, degradation, mechanical and rheological tests, printability analysis, biocompatibility and chondrogenic differentiation characterization, and RNA sequencing (RNA-seq). The results indicated that the photo-cross-linked ECM hydrogels possessed suitable degradation rate and excellent mechanical properties, and the three-dimensional (3D) bioprinted ECM scaffolds obtained favorable shape fidelity and improved the basic properties, biological properties, and chondrogenesis of synovium-derived MSCs (SMSCs). The strong stimulation of transforming growth factor-beta 1 (TGF-β1) enhanced the aggregation, proliferation, and differentiation of SMSCs, thereby enhancing chondrogenic ECM deposition. In vivo animal experiments and gait analysis further confirmed that the ECM scaffold combined with TGF-β1 could effectively promote cartilage regeneration and functional recovery of injured joints. To sum up, the photo-cross-linked ECM bioink for 3D printing of functional cartilage tissue may become an attractive strategy for cartilage regeneration.

Osteochondral defect caused by trauma or osteoarthritis exhibits a major challenge in clinical treatment with limited symptomatic effects at present. The regeneration and remodeling of subchondral bone play a positive effect on cartilage regeneration and further promotes the repair of osteochondral defects. Making use of the strengths of each preparation method, the combination of 3D printing and electrospinning is a promising method for designing and constructing multiscale scaffolds that mimic the complexity and hierarchical structure of subchondral bone at the microscale and nanoscale, respectively. In this study, the 3D printed-electrospun poly(ɛ-caprolactone)/nano-hydroxyapatites/multi-walled carbon nanotubes (PCL/nHA/MWCNTs) scaffolds were successfully constructed by the combination of electrospinning and layer-by-layer 3D printing. The resulting dual-scale scaffold consisted of a dense layer of disordered nanospun fibers and a porous microscale 3D scaffold layer to support and promote the ingrowth of subchondral bone. Herein, the biomimetic PCL/nHA/MWCNTs scaffolds enhanced cell seeding efficiency and allowed for higher cell-cell interactions that supported the adhesion, proliferation, activity, morphology and subsequently improved the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. Together, this study elucidates that the construction of 3D printed-electrospun PCL/nHA/MWCNTs scaffolds provides an alternative strategy for the regeneration of subchondral bone and lays a foundation for subsequent in vivo studies.