Dual-response of multi-functional microsphere system to ultrasound and microenvironment for enhanced bone defect treatment

Smart Polymer Microspheres: Preparation, Microstructures, Stimuli-Responsive Properties, and Applications

Smart polymer microspheres (SPMs) are a class of stimulus-responsive materials that undergo physical, chemical, or property changes in response to external stimuli, such as temperature, pH, light, and magnetic fields. In recent years, their diverse responsiveness and tunable structures have enabled broad applications in biomedicine, environmental protection, information encryption, and other fields. This study provides a detailed review of recent preparation methods of SPMs, focusing on physical methods such as emulsification-solvent evaporation, microfluidics, and electrostatic spraying as well as chemical approaches such as emulsion and precipitation polymerization. Meanwhile, different types of stimulus-responsive behaviors, such as temperature-, pH-, light-, and magnetic-responsiveness, are thoroughly examined. This study also explores the applications of SPMs in drug delivery, tissue engineering, and environmental monitoring, while discussing future technological challenges and development directions in this field.

Thermoresponsive dual-network chitosan-based hydrogels with demineralized bone matrix for controlled release of rhBMP9 in the treatment of femoral head osteonecrosis

In an effort to mitigate or reverse the pathological progression of early-stage osteonecrosis of the femoral head (ONFH), this study employed a promising strategy that involves the sustained delivery of osteogenic factors to augment core decompression, facilitated by the use of composite hydrogels. Specifically, a hydrogel was synthesized by blending chitosan, Pluronic F-127, and tripolyphosphate, utilizing both ionic bonding and copolymer micelle cross-linking techniques. This hydrogel demonstrated exceptional biocompatibility, temperature responsiveness, pH-dependent biodegradation, and controlled release properties. The average pore diameter of the optimal hydrogel expanded to 45 μm, accompanied by zeta potentials of +34.72 ± 4.13 mV. The loading efficiency notably surpassed 90 %, while the sustained release of recombinant human bone morphogenetic proteins 9 (rhBMP9) was observed to last over 25 days at pH = 6.0 and over 36 days at pH = 7.4. This chitosan-based hydrogel, which sustained rhBMP9 release, significantly enhanced the proliferation and migration of bone marrow mesenchymal stem cells and human umbilical vein endothelial cells and promoted osteogenesis and angiogenesis both in vitro and in vivo. Collectively, our study presents an rhBMP9-loaded chitosan-based composite hydrogel system that offers innovative avenues for the research and clinical application of advanced biomaterials in the treatment of early ONFH.

Bioprinted hydrogels in bone regeneration: a bibliometric analysis

Background

The application of bioprinted hydrogels in the field of bone regeneration is garnering increasing attention. The objective of this study is to provide a comprehensive overview of the current research status, hotspots and research directions in this field through bibliometric methods, and to predict the development trend of this field.

Methods

A search was conducted on 27 December 2024, for papers published on the Web of Science from 2010 to 2025. We used the bibliometrix package in the software program R to analyze the retrieved data and VOSviewer and CiteSpace to visualize hotspots and research trends in bioprinted hydrogels for bone regeneration.

Results

We identified and reviewed 684 articles published in this field between 2010 and 2025. A total of 811 institutions and 1,166 researchers from 41 countries/regions contributed to these publications. Among them, China led in terms of the number of articles published, single-country publications (SCP), and multi-country publications (MCP). Our bibliometric-based visualization analysis revealed that the mechanical properties and osteogenic differentiation capacity of biomaterials have been a focal research topic over the past decade, while emerging research has also concentrated on the in vitro fabrication of stem cells for bone regeneration and osteogenic differentiation, particularly the precise application of in situ stem cell-loaded bioprinted organoids.

Conclusion

This study provides an in-depth analysis of the research trajectory in the application of bioprinted hydrogels for bone regeneration. The number of research papers in this field is increasing annually, and the main research hotspots include bone regeneration, 3D printing, scaffolds, and hydrogels. Future research directions may focus on gelatin, additive manufacturing, and growth factors. Additionally, international collaboration is essential to enhance the effectiveness of bioprinted hydrogels in bone regeneration applications.

Incorporating Hydrogel (with Low Polymeric Content) into 3D-Printed PLGA Scaffolds for Local and Sustained Release of BMP2 in Repairing Large Segmental Bone Defects

Treating large bone defects remains a considerable challenge for clinicians: bone repair requires scaffolds with mechanical properties and bioactivities. Herein, based on crosslinking o-phthalaldehyde (OPA) with amine groups, 4-arm polyethylene glycol (4armPEG)-OPA/Gelatin hydrogel loaded with bone morphogenetic protein 2 (BMP2) is prepared and a three dimensional (3D)-printed poly (lactic-co-glycolic acid) (PLGA) porous scaffold is filled with the hydrogel solution. The composite scaffold, with a compression modulus of 0.68 ± 0.097 GPa similar to the cancellous bone, has a porosity of 56.67 ± 4.72% and a pore size of about 380 µm, promoting bone growth. The hydrogel forms a porous network at low concentrations, aiding protein release and cell migration. The hydrogel degrades in approximately three weeks, and the scaffold takes five months, matching bone repair timelines. BMP2 release experiment shows a sustained BMP2 release with a 72.4 ± 0.53% release ratio. The ALP activity test and alizarin red staining shows effective osteogenic promotion, while RT-PCR confirms BMP2@Gel enhanced COL-1 and OPN expression. Animal experiments further validate the composite scaffold's bone repair efficacy. This study demonstrates the effectiveness of the hydrogel in releasing BMP2 and the mechanical support of the 3D-printed PLGA porous scaffold, providing a new treatment for bone defects.

Nanocarriers for intracellular delivery of proteins in biomedical applications: strategies and recent advances

Protein drugs are of great importance in maintaining the normal functioning of living organisms. Indeed, they have been instrumental in combating tumors and genetic diseases for decades. Among these pharmaceutical agents, those that target intracellular components necessitate the use of therapeutic proteins to exert their effects within the targeted cells. However, the use of protein drugs is limited by their short half-life and potential adverse effects in the physiological environment. The advent of nanoparticles offers a promising avenue for prolonging the half-life of protein drugs. This is achieved by encapsulating proteins, thereby safeguarding their biological activity and ensuring precise delivery into cells. This nanomaterial-based intracellular protein drug delivery system mitigates the rapid hydrolysis and unwarranted diffusion of proteins, thereby minimizing potential side effects and circumventing the limitations inherent in traditional techniques like electroporation. This review examines established protein drug delivery systems, including those based on polymers, liposomes, and protein nanoparticles. We delve into the operational principles and transport mechanisms of nanocarriers, discussing the various considerations essential for designing cutting-edge delivery platforms. Additionally, we investigate innovative designs and applications of traditional cytosolic protein delivery systems in medical research and clinical practice, particularly in areas like tumor treatment, gene editing and fluorescence imaging. This review sheds light on the current restrictions of protein delivery systems and anticipates future research avenues, aiming to foster the continued advancement in this field.

Cell-homing and immunomodulatory composite hydrogels for effective wound healing with neovascularization

Wound healing in cases of excessive inflammation poses a significant challenge due to compromised neovascularization. Here, we propose a multi-functional composite hydrogel engineered to overcome such conditions through recruitment and activation of macrophages with adapted degradation of the hydrogel. The composite hydrogel (G-TSrP) is created by combining gelatin methacryloyl (GelMA) and nanoparticles (TSrP) composed of tannic acid (TA) and Sr2+. These nanoparticles are prepared using a one-step mineralization process assisted by metal-phenolic network formation. G-TSrP exhibits the ability to eliminate reactive oxygen species and direct polarization of macrophages toward M2 phenotype. It has been observed that the liberation of TA and Sr2+ from G-TSrP actively facilitate the recruitment and up-regulation of the expression of extracellular matrix remodeling genes of macrophages, and thereby, coordinate in vivo adapted degradation of the G-TSrP. Most significantly, G-TSrP accelerates angiogenesis despite the TA's inhibitory properties, which are counteracted by the released Sr2+. Moreover, G-TSrP enhances wound closure under inflammation and promotes normal tissue formation with strong vessel growth. Genetic analysis confirms macrophage-mediated wound healing by the composite hydrogel. Collectively, these findings pave the way for the development of biomaterials that promote wound healing by creating regenerative environment.