Photocuring 3D Printing of Hydrogels: Techniques, Materials, and Applications in Tissue Engineering and Flexible Devices

PEDOT:PSS-based bioelectronics for brain monitoring and modulation

The growing demand for advanced neural interfaces that enable precise brain monitoring and modulation has catalyzed significant research into flexible, biocompatible, and highly conductive materials. PEDOT:PSS-based bioelectronic materials exhibit high conductivity, mechanical flexibility, and biocompatibility, making them particularly suitable for integration into neural devices for brain science research. These materials facilitate high-resolution neural activity monitoring and provide precise electrical stimulation across diverse modalities. This review comprehensively examines recent advances in the development of PEDOT:PSS-based bioelectrodes for brain monitoring and modulation, with a focus on strategies to enhance their conductivity, biocompatibility, and long-term stability. Furthermore, it highlights the integration of multifunctional neural interfaces that enable synchronous stimulation-recording architectures, hybrid electro-optical stimulation modalities, and multimodal brain activity monitoring. These integrations enable fundamentally advancing the precision and clinical translatability of brain-computer interfaces. By addressing critical challenges related to efficacy, integration, safety, and clinical translation, this review identifies key opportunities for advancing next-generation neural devices. The insights presented are vital for guiding future research directions in the field and fostering the development of cutting-edge bioelectronic technologies for neuroscience and clinical applications.

Advances in Digital Light Processing (DLP) Bioprinting: A Review of Biomaterials and Its Applications, Innovations, Challenges, and Future Perspectives

Digital light processing (DLP) technology stands out as a groundbreaking method in the field of biomedical engineering that enables the production of highly precise structures using photopolymerizable materials. Smart materials such as shape memory polymers, hydrogels, and nanocomposites are used as ideal materials for personalized medicine applications thanks to their properties such as superior mechanical strength, biocompatibility, and sensitivity to environmental stimuli in DLP technology. The integration of these materials with DLP enables the production of functional and complex structures, especially in areas such as bone and soft tissue engineering, drug delivery, and biosensor production. However, limited material diversity, scalability problems in production processes, and technical difficulties in optimizing bioprinting parameters are among the main obstacles in this field. This study systematically examines the role of smart biomaterials in DLP-based bioprinting processes. It addresses the innovative applications of these materials in tissue engineering and regenerative medicine. It also comprehensively evaluates its contributions to biomedical applications and discusses future research areas to overcome current limitations.

Effects of 3D-printed exosome-functionalized brain acellular matrix hydrogel on neuroinflammation in rats following cerebral hemorrhage

BACKGROUND

Exosome-based therapeutics have garnered significant attention for intracerebral hemorrhage (ICH) treatment due to their capacity to regulate metabolic dysregulation, restore cellular homeostasis, and modulate the injury microenvironment via bioactive cargoes such as microRNAs and proteins. However, rapid systemic clearance and enzymatic degradation critically limit their therapeutic efficacy. To address this challenge, we engineered a three-dimensional (3D) bioprinted scaffold capable of encapsulating and sustaining the release of human umbilical cord mesenchymal stem cell-derived exosomes (hUCMSC-exos).

METHODS

Based on previous research [1-3], the scaffold was composed of a decellularized brain matrix (dECM), gelatin-methacryloyl (GelMA), and silk fibroin (SF) crosslinked with a photoinitiator. hUCMSC-exos were precisely incorporated via extrusion-based 3D bioprinting. Release kinetics were assessed via in vitro elution and in vivo imaging. An ICH rat model received stereotaxic implantation of the exosome-laden scaffold (dECM@exo). Neuroinflammatory markers (IL-6, TNF-α, IL-10) and apoptotic activity (JC-1, Annexin V/PI, TUNEL) were quantified. Neurological outcomes were longitudinally evaluated using the modified Longa scale, Bederson scoring, and sensorimotor tests (rotarod, forelimb placement) at 1, 4, 7 and 14 days post-ICH.

RESULTS

dECM@exo demonstrated sustained exosome release over 14 days, significantly promoting neural tissue regeneration while attenuating perihematomal edema. Mechanistically, the scaffold modulated pathological MMP activity and inflammatory cytokine expression, thereby restoring extracellular matrix homeostasis and reducing neuronal apoptosis.

CONCLUSIONS

The findings demonstrate that the 3D biological scaffold dECM@exo effectively maintains microenvironmental homeostasis in the early stages of ICH and improves outcomes associated with the condition. dECM@exo is poised to serve as a robust platform for drug delivery and biotherapy in ICH treatment, offering a viable alternative for managing this condition.

Soft Actuators and Actuation: Design, Synthesis, and Applications

Soft actuators are one of the most promising technological advancements with potential solutions to diverse fields' day-to-day challenges. Soft actuators derived from hydrogel materials possess unique features such as flexibility, responsiveness to stimuli, and intricate deformations, making them ideal for soft robotics, artificial muscles, and biomedical applications. This review provides an overview of material composition and design techniques for hydrogel actuators, exploring 3D printing, photopolymerization, cross-linking, and microfabrication methods for improved actuation. It examines applications of hydrogel actuators in biomedical, soft robotics, bioinspired systems, microfluidics, lab-on-a-chip devices, and environmental, and energy systems. Finally, it discusses challenges, opportunities, advancements, and regulatory aspects related to hydrogel actuators.

Understanding the cellular dynamics, engineering perspectives and translation prospects in bioprinting epithelial tissues

The epithelium is one of the important tissues in the body as it plays a crucial barrier role serving as a gateway into and out of the body. Most organs in the body contain an epithelial tissue component, where the tightly connected, organ-specific epithelial cells organize into cysts, invaginations, or tubules, thereby performing distinct to endocrine or exocrine secretory functions. Despite the significance of epithelium, engineering functional epithelium in vitro has remained a challenge due to it is special architecture, heterotypic composition of epithelial tissues, and most importantly, difficulty in attaining the apico-basal and planar polarity of epithelial cells. Bioprinting has brought a paradigm shift in fabricating such apico-basal polarized tissues. In this review, we provide an overview of epithelial tissues and provide insights on recapitulating their cellular arrangement and polarization to achieve epithelial function. We describe the different bioprinting techniques that have been successful in engineering polarized epithelium, which can serve as in vitro models for understanding homeostasis and studying diseased conditions. We also discuss the different attempts that have been investigated to study these 3D bioprinted engineered epithelium for preclinical use. Finally, we highlight the challenges and the opportunities that need to be addressed for translation of 3D bioprinted epithelial tissues towards paving way for personalized healthcare in the future.

3D digital light process bioprinting: Cutting-edge platforms for resolution of organ fabrication

Research in the field of regenerative medicine, which replaces or restores the function of human damaged organs is advancing rapidly. These advances are fostering important innovations in the development of artificial organs. In recent years, three-dimensional (3D) bioprinting has emerged as a promising technology for regenerative medicine applications. Among various techniques, digital light process (DLP) 3D bioprinting stands out for its ability to precisely create high-resolution, structurally complex artificial organs. This review explores the types and usage trends of DLP printing equipment, bioinks, and photoinitiators. Building on this foundation, the applications of DLP bioprinting for creating precise microstructures of human organs and for regenerating tissue and organ models in regenerative medicine are examined. Finally, challenges and future perspectives regarding DLP-based bioprinting, particularly for precision printing applications in regenerative medicine, are discussed.

3D biological scaffold delivers Bergenin to reduce neuroinflammation in rats with cerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is a severe form of stroke characterized by high incidence and mortality rates. Currently, there is a significant lack of effective treatments aimed at improving clinical outcomes. Our research team has developed a three-dimensional (3D) biological scaffold that incorporates Bergenin, allowing for the sustained release of the compound.

METHODS

This 3D biological scaffold was fabricated using a combination of photoinitiator, GEMA, silk fibroin, and decellularized brain matrix (dECM) to encapsulate Bergenin through advanced 3D bioprinting techniques. The kinetics of drug release were evaluated through both in vivo and in vitro studies. A cerebral hemorrhage model was established, and a 3D biological scaffold containing Bergenin was transplanted in situ. Levels of inflammatory response, oxidative stress, and apoptosis were quantified. The neurological function of rats with cerebral hemorrhage was assessed on days 1, 3, and 5 using the turning test, forelimb placement test, Longa score, and Bederson score.

RESULTS

The 3D biological scaffold incorporating Bergenin significantly enhances the maintenance of drug concentration in the bloodstream, leading to a marked reduction in inflammatory markers such as IL-6, iNOS, and COX-2 levels in a cerebral hemorrhage model, primarily through the inhibition of the NF-κB pathway. Additionally, the scaffold effectively reduces the expression of hypoxia-inducible factor 1-alpha (HIF-1α) in primary cultured astrocytes, which in turn decreases the production of reactive oxygen species (ROS) and inhibits IL-6 production induced by hemin. Subsequent experiments reveal that the 3D biological scaffold containing Bergenin promotes the activation of the Nrf-2/HO-1 signaling pathway, both in vivo and in vitro, thereby preventing cell death. Moreover, the application of this 3D biological scaffold has been demonstrated to improve drug retention in the bloodstream.

CONCLUSION

This strategy effectively mitigates inflammation, oxidative stress, and cell death in rats with cerebral hemorrhage by inhibiting the NF-κB pathway while concurrently activating the Nrf-2/HO-1 pathway.

Structural Functions of 3D-Printed Polymer Scaffolds in Regulating Cell Fates and Behaviors for Repairing Bone and Nerve Injuries

Tissue repair and regeneration, such as bone and nerve restoration, face significant challenges due to strict regulations within the immune microenvironment, stem cell differentiation, and key cell behaviors. The development of 3D scaffolds is identified as a promising approach to address these issues via the efficiently structural regulations on cell fates and behaviors. In particular, 3D-printed polymer scaffolds with diverse micro-/nanostructures offer a great potential for mimicking the structures of tissue. Consequently, they are foreseen as promissing pathways for regulating cell fates, including cell phenotype, differentiation of stem cells, as well as the migration and the proliferation of key cells, thereby facilitating tissue repairs and regenerations. Herein, the roles of structural functions of 3D-printed polymer scaffolds in regulating the fates and behaviors of numerous cells related to tissue repair and regeneration, along with their specific influences are highlighted. Additionally, the challenges and outlooks associated with 3D-printed polymer scaffolds with various structures for modulating cell fates are also discussed.