Transient implantable piezoelectric materials are desirable for biosensing, drug delivery, tissue regeneration, and antimicrobial and tumor therapy. For use in the human body, they must show flexibility, biocompatibility, and biodegradability. These requirements are challenging for conventional inorganic piezoelectric oxides and piezoelectric polymers. We discovered high piezoelectricity in a molecular crystal HOCH ₂ (CF ₂ ) ₃ CH ₂ OH [2,2,3,3,4,4-hexafluoropentane-1,5-diol (HFPD)] with a large piezoelectric coefficient d ₃₃ of ~138 picocoulombs per newton and piezoelectric voltage constant g ₃₃ of ~2450 × 10 ⁻³ volt-meters per newton under no poling conditions, which also exhibits good biocompatibility toward biological cells and desirable biodegradation and biosafety in physiological environments. HFPD can be composite with polyvinyl alcohol to form flexible piezoelectric films with a d ₃₃ of 34.3 picocoulombs per newton. Our material demonstrates the ability for molecular crystals to have attractive piezoelectric properties and should be of interest for applications in transient implantable electromechanical devices.

Osteoporosis is the most common degenerative orthopedic disease in the elderly. Recently, the therapeutic methods for osteoporosis have shifted towards the regulation of local immunity in bone tissues, which could provide a suitable environment for the positive regulation of bone metabolism, promoting osteogenic differentiation and inhibiting osteoclast differentiation. Our previous work demonstrated that iron oxide nanoparticles (IONPs) could positively regulate bone metabolism in vitro. In this study, we further demonstrated that daily administration of IONPs relieved estrogen deficiency-induced osteoporosis via scavenging reactive oxygen species in vivo. Meanwhile, IONPs promoted the osteogenic differentiation of bone marrow mesenchymal stem cells and inhibited the osteoclast differentiation of monocytes from IONPs treated mice. Besides, alendronate, a clinically used anti-osteoporosis bisphosphate, was employed to precisely deliver the IONPs to the bone tissues and played a synergically therapeutic role. Eventually, we verified the bone targeting ability, therapeutic efficiency, and biocompatibility of the novel bone target iron oxides in ovariectomy-induced osteoporotic mice. By applying BTNPs, the OVX-induced osteoporosis was significantly revised in mice models via the positive regulation of bone metabolism.

Lignin from different biomasses possess biological antioxidation and antimicrobial activities, which depend on the number of functional groups and the molecular weight of lignin. In this work, organosolv fractionation was carried out to prepare the lignin fraction with a suitable structure to tailor excellent biological activities. Gel permeation chromatography (GPC) analysis showed that decreased molecular weight lignin fractions were obtained by sequentially organosolv fractionation with anhydrous acetone, 50% acetone and 37.5% hexanes. Nuclear magnetic resonance (NMR) results indicated that the lignin fractions with lower molecular weight had fewer substructures and a higher phenolic hydroxyl content, which was positively correlated with their antioxidation ability. Both of the original lignin and fractionated lignins possessed the ability to inhibit the growth of Gram-negative bacteria (Escherichia coli and Salmonella) and Gram-positive bacteria (Streptococcus and Staphylococcus aureus) by destroying the cell wall of bacteria in vitro, in which the lignin fraction with the lowest molecular weight and highest phenolic hydroxyl content (L3) showed the best performance. Besides, the L3 lignin showed the ability to ameliorate Escherichia coli-induced diarrhea damages of mice to improve the formation of intestinal contents in vivo. These results imply that a lignin fraction with a tailored structure from bamboo lignin can be used as a novel antimicrobial agent in the biomedical field.

Accumulating research has indicated that the transplantation of combined stem cells and scaffolds is an effective method for spinal cord injury (SCI). The development of three-dimensional (3D) bioprinting technology can make the 3D scaffolds combined with cells more accurate and effective for SCI treatment. However, unmyelinated newborn nerve fibers have no nerve signaling conduction, hampering recovery of motor function. In this study, we designed and printed a type of sodium alginate/gelatin scaffold loaded with neural stem cells and oligodendrocytes, which were involved in the formation of the myelin sheaths of neural cell axons. In order to observe the effectiveness of this 3D bioprinting scaffold, we transplanted it into the completely transected rat spinal cord, and then immunofluorescence staining, hematoxylin–eosin staining and behavioral assessment were performed. The results showed that this 3D bioprinting scaffold markedly improved the hindlimb motor function and promoted nerve regeneration. These findings suggested that this novel 3D bioprinting scaffold was a good carrier for cells transplantation, thereby enhancing spinal cord repair following injury.

RNA interference (RNAi) and oxidative stress inhibition therapeutic strategies have been extensively utilized in the treatment of osteoarthritis (OA), the most prevalent degenerative joint disease. However, the synergistic effects of these approaches on attenuating OA progression remain largely unexplored. In this study, matrix metalloproteinase-13 siRNA (siMMP-13) was incorporated onto polyethylenimine (PEI)-polyethylene glycol (PEG) modified Fe3O4 nanoparticles, forming a nucleic acid nanocarrier termed si-Fe NPs. Subsequently, a poly(vinyl alcohol) (PVA) crosslinked phenylboronic acid (PBA)-modified hyaluronic acid (HA) hydrogel (HPP) was used to encapsulate the si-Fe NPs, resulting in a bifunctional hydrogel (si-Fe-HPP) with reactive oxygen species (ROS)-responsive and RNAi therapeutic properties. Studies in vitro demonstrated that si-Fe-HPP exhibited excellent biocompatibility, anti-inflammatory effects and prolonged stable retention time in knee joint. Intra-articular injection of si-Fe-HPP significantly attenuated cartilage degradation in mice with destabilization of the medial meniscus (DMM)-induced OA. The si-Fe-HPP treatment not only notably alleviated synovitis, osteophyte formation and subchondral bone sclerosis, but also markedly improved physical activity and reduced pain in DMM-induced OA mice. This study reveals that si-Fe-HPP, with its ROS-responsive and RNAi abilities, can significantly protect chondrocytes and attenuate OA progression, providing novel insights and directions for the development of therapeutic materials for OA treatment.