Near-Infrared Light-Sensitive Polyvinyl Alcohol Hydrogel Photoresist for Spatiotemporal Control of Cell-Instructive 3D Microenvironments

Bioengineering approaches for the endometrial research and application

The endometrium undergoes a series of precise monthly changes under the regulation of dynamic levels of ovarian hormones that are characterized by repeated shedding and subsequent regeneration without scarring. This provides the potential for wound healing during endometrial injuries. Bioengineering materials highlight the faithful replication of constitutive cells and the extracellular matrix that simulates the physical and biomechanical properties of the endometrium to a larger extent. Significant progress has been made in this field, and functional endometrial tissue bioengineering allows an in-depth investigation of regulatory factors for endometrial and myometrial defects in vitro and provides highly therapeutic methods to alleviate obstetric and gynecological complications. However, much remains to be learned about the latest progress in the application of bioengineering technologies to the human endometrium. Here, we summarize the existing developments in biomaterials and bioengineering models for endometrial regeneration and improving the female reproductive potential.

Multimaterial 3D Laser Printing of Cell-Adhesive and Cell-Repellent Hydrogels

Here, a straightforward method is reported for manufacturing 3D microstructured cell-adhesive and cell-repellent multimaterials using two-photon laser printing. Compared to existing strategies, this approach offers bottom-up molecular control, high customizability, and rapid and precise 3D fabrication. The printable cell-adhesive polyethylene glycol (PEG) based material includes an Arg-Gly-Asp (RGD) containing peptide synthesized through solid-phase peptide synthesis, allowing for precise control of the peptide design. Remarkably, minimal amounts of RGD peptide (< 0.1 wt%) suffice for imparting cell-adhesiveness, while maintaining identical mechanical properties in the 3D printed microstructures to those of the cell-repellent, PEG-based material. Fluorescent labeling of the RGD peptide facilitates visualization of its presence in cell-adhesive areas. To demonstrate the broad applicability of the system, the fabrication of cell-adhesive 2.5D and 3D structures is shown, fostering the adhesion of fibroblast cells within these architectures. Thus, this approach allows for the printing of high-resolution, true 3D structures suitable for diverse applications, including cellular studies in complex environments.

Swarm Autonomy: From Agent Functionalization to Machine Intelligence

Swarm behaviors are common in nature, where individual organisms collaborate via perception, communication, and adaptation. Emulating these dynamics, large groups of active agents can self-organize through localized interactions, giving rise to complex swarm behaviors, which exhibit potential for applications across various domains. This review presents a comprehensive summary and perspective of synthetic swarms, to bridge the gap between the microscale individual agents and potential applications of synthetic swarms. It is begun by examining active agents, the fundamental units of synthetic swarms, to understand the origins of their motility and functionality in the presence of external stimuli. Then inter-agent communications and agent-environment communications that contribute to the swarm generation are summarized. Furthermore, the swarm behaviors reported to date and the emergence of machine intelligence within these behaviors are reviewed. Eventually, the applications enabled by distinct synthetic swarms are summarized. By discussing the emergent machine intelligence in swarm behaviors, insights are offered into the design and deployment of autonomous synthetic swarms for real-world applications.

Stepwise Stiffening/Softening of and Cell Recovery from Reversibly Formulated Hydrogel Double Networks

Biomechanical contributions of the ECM underpin cell growth and proliferation, differentiation, signal transduction, and other fate decisions. As such, biomaterials whose mechanics can be spatiotemporally altered - particularly in a reversible manner - are extremely valuable for studying these mechanobiological phenomena. Herein, we introduce a poly(ethylene glycol) (PEG)-based hydrogel model consisting of two interpenetrating step-growth networks that are independently formed via largely orthogonal bioorthogonal chemistries and sequentially degraded with distinct bacterial transpeptidases, affording reversibly tunable stiffness ranges that span healthy and diseased soft tissues (e.g., 500 Pa - 6 kPa) alongside terminal cell recovery for pooled and/or single-cell analysis in a near "biologically invisible" manner. Spatiotemporal control of gelation within the primary supporting network was achieved via mask-based and two-photon lithography; these stiffened patterned regions could be subsequently returned to the original soft state following sortase-based secondary network degradation. Using this approach, we investigated the effects of 4D-triggered network mechanical changes on human mesenchymal stem cell (hMSC) morphology and Hippo signaling, as well as Caco-2 colorectal cancer cell mechanomemory at the global transcriptome level via RNAseq. We expect this platform to be of broad utility for studying and directing mechanobiological phenomena, patterned cell fate, as well as disease resolution in softer matrices.

Microenvironment with NIR-Controlled ROS and Mechanical Tensions for Manipulating Cell Activities in Wound Healing

The extracellular matrix (ECM) orchestrates cell behavior and tissue regeneration by modulating biochemical and mechanical signals. Manipulating cell-material interactions is crucial for leveraging biomaterials to regulate cell functions. Yet, integrating multiple cues in a single material remains a challenge. Here, near-infrared (NIR)-controlled multifunctional hydrogel platforms, named PIC/CM@NPs, are introduced to dictate fibroblast behavior during wound healing by tuning the matrix oxidative stress and mechanical tensions. PIC/CM@NPs are prepared through cell adhesion-medicated assembly of collagen-like polyisocyanide (PIC) polymers and cell-membrane-coated conjugated polymer nanoparticles (CM@NPs), which closely mimic the fibrous structure and nonlinear mechanics of ECM. Upon NIR stimulation, PIC/CM@NPs composites enhance fibroblast cell proliferation, migration, cytokine production, and myofibroblast activation, crucial for wound closure. Moreover, they exhibit effective and toxin removal antibacterial properties, reducing inflammation. This multifunctional approach accelerates healing by 95%, highlighting the importance of integrating biochemical and biophysical cues in the biomaterial design for advanced tissue regeneration.

Photo-responsive hydrogels based on a ruthenium complex: synthesis and degradation

We report the synthesis of a photo responsive metallo-hydrogel based on a ruthenium(II) complex as a functional cross-linker. This metal complex contains reactive 4AAMP (= 4-(acrylamidomethyl)pyridine) ligands, which can be cleaved by light-induced ligand substitution. Ru[(bpy)2(4AAMP)2] cross-links 4-arm-PEG-SH macromonomers by thia-Michael-addition to the photocleavable 4AAMP ligand for the preparation of the hydrogel. Irradiation with green light at 529 nm leads to photodegradation of the metallo-hydrogel due to the ligand dissociation, which can be adjusted by adjusting the Ru[(bpy)2(4AAMP)2] concentration. The ligand substitution forming [Ru(bpy)2(L)2]2+ (L = H2O and CH3CN) can be monitored by 1H NMR spectroscopy and UV-visible absorption. The control of degradation by light irradiation plays a significant role in modulating the elasticity and stiffness of the light sensitive metallo-hydrogel network. The photo-responsive hydrogel is a viable substrate for cell cultures.

Synergizing Algorithmic Design, Photoclick Chemistry and Multi-Material Volumetric Printing for Accelerating Complex Shape Engineering

The field of biomedical design and manufacturing has been rapidly evolving, with implants and grafts featuring complex 3D design constraints and materials distributions. By combining a new coding-based design and modeling approach with high-throughput volumetric printing, a new approach is demonstrated to transform the way complex shapes are designed and fabricated for biomedical applications. Here, an algorithmic voxel-based approach is used that can rapidly generate a large design library of porous structures, auxetic meshes and cylinders, or perfusable constructs. By deploying finite cell modeling within the algorithmic design framework, large arrays of selected auxetic designs can be computationally modeled. Finally, the design schemes are used in conjunction with new approaches for multi-material volumetric printing based on thiol-ene photoclick chemistry to rapidly fabricate complex heterogeneous shapes. Collectively, the new design, modeling and fabrication techniques can be used toward a wide spectrum of products such as actuators, biomedical implants and grafts, or tissue and disease models.

Poly(vinyl alcohol) Modified via the Hantzsch Reaction for Biosafe Antioxidant Self-Healing Hydrogel

Efficient routes for the preparation of functional self-healing hydrogels from functional polymers are needed. In this study, we developed a strategy to effectively produce a vanillin-modified poly(vinyl alcohol) (PVA-vanillin) through the Hantzsch reaction. This polymer was cross-linked with a phenylboronic acid-containing polymer (PB) that was also prepared using the Hantzsch reaction to fabricate a hydrogel through borate ester linkages under mild conditions (25 °C, pH ∼ 7.4). This hydrogel had excellent antioxidant abilities due to the 1,4-dihydropyridine (DHP) rings and the vanillin moieties in the hydrogel structures; it was also self-healable and injectable owing to the dynamic borate ester linkages. Furthermore, the antioxidant self-healing hydrogel had low cytotoxicity and exhibited favorable safety in animal experiments, indicating its potential as a safe implantable cell or drug carrier. This study developed a method for preparing functional polymers and related self-healing hydrogels in a facile manner; it demonstrated the value of the Hantzsch reaction in exploiting antioxidant self-healing hydrogels for biomedical applications, which may provide insight into the design of other functional self-healing hydrogels through different multicomponent reactions.

Matrix scaffolds for endometrium-derived organoid models

The uterus-lining endometrium is essential to mammalian reproduction, receiving and accommodating the embryo for proper development. Despite its key role, mechanisms underlying endometrial biology (menstrual cycling, embryo interaction) and disease are not well understood. Its hidden location in the womb, and thereby-associated lack of suitable research models, contribute to this knowledge gap. Recently, 3D organoid models have been developed from both healthy and diseased endometrium. These organoids closely recapitulate the tissue's epithelium phenotype and (patho)biology, including in vitro reproduction of the menstrual cycle. Typically, organoids are grown in a scaffold made of surrogate tissue extracellular matrix (ECM), with mouse tumor basement membrane extracts being the most commonly used. However, important limitations apply including their lack of standardization and xeno-derivation which strongly hinder clinical translation. Therefore, researchers are actively seeking better alternatives including fully defined matrices for faithful and efficient growth of organoids. Here, we summarize the state-of-the-art regarding matrix scaffolds to grow endometrium-derived organoids as well as more advanced organoid-based 3D models. We discuss remaining shortcomings and challenges to advance endometrial organoids toward defined and standardized tools for applications in basic research and translational/clinical fields.

Engineered Injectable Cell-Laden Chitin/Chitosan Hydrogel with Adhesion and Biodegradability for Calvarial Defect Regeneration

Trade-off of high-strength and dynamic crosslinking of hydrogels remains an enormous challenge. Motivated by the self-healing property of biological tissues, the strategy of combining multiple dynamic bond mechanisms and a polysaccharide network is proposed to fabricate biomimetic hydrogels with sufficient mechanical strength, injectability, biodegradability, and self-healing property for bone reconstruction engineering. Stable acylhydrazone bonds endowed hydrogels with robust mechanical strength (>10 kPa). The integration of dynamic imine bonds and acylhydrazone bonds optimized the reversible characteristic to protect the cell during the injection and mimicked ECM microenvironment for cell differentiation as well as rapid adapting bone defect area. Furthermore, due to the slow enzymatic hydrolysis kinetics of chitosan and the self-healing properties of resulting networks, hydrogels exhibited a satisfactory biodegradation period (>8 weeks) that highly matches with bone regeneration. Additionally, rBMSC-laden hydrogels exhibited splendid osteogenic induction and bone reconstruction without prefabrication scaffolds and incubation, demonstrating tremendous potential for clinical application. This work proposes an efficient strategy for the construction of a low-cost multifunctional hydrogel, making polysaccharide-based hydrogels as the optimal carrier for enabling cellular functions in bone repair.

Nano-based eye drop: Topical and noninvasive therapy for ocular diseases

Eye drops are the most accessible therapy for ocular diseases, while inevitably suffering from their lower bioavailability which highly restricts the treatment efficacy. The introduction of nanotechnology has attracted considerable interest as it has advantages over conventional ones such as prolonged ocular surface retention time and enhanced ocular barrier penetrating properties, and achieving higher bioavailability and improved treatment efficacy. This review describes various ocular diseases treated with eye drops as well as the physiological and anatomical ocular barriers faced with through drug administration. It also summarizes the recent advances regarding the utilization of nanotechnology in developing eye drops, and how to optimize the nanocarrier-based ocular drug delivery systems. The prospective future research directions for nano-based eye drops are also discussed here.

Fabrication of Thermo-Responsive Controllable Shape-Changing Hydrogel

Temperature response double network (DN) hydrogels comprising a network formed by polymerization of methacrylic acid (MA) modified PVA, N,N’-methylene bis(acrylamide), N-isopropylacryl amide (NIPAM), and one formed from crystalline polyvinyl alcohol (PVA) are prepared in a 3D printed tailor-made mold. The (PVA-MA)-g-PNIPAAm thermoset intermediate is formed in water by a radical, photo-initiated process, and in the presence of dissolved PVA polymers. A subsequent freezing-thawing sequence induces the crystallization of the PVA network, which forms a second network inside the thermoset NIPAM polymer. The prepared hydrogel is thermoresponsive by the phase transition of PNIPAAm segments (T ≈ 32 °C) and has good mechanical properties (tensile strength 1.23 MPa, compressive strength 1.47 MPa). Thermal cycling between room temperature at 40 or 50 °C shows the product converses from a virgin-state to a steady-state, which most likely involves the reorganization of PVA crystals. The swelling-deswelling cycles remain clear at a length change of about 13%.

Macroporous Aligned Hydrogel Microstrands for 3D Cell Guidance

Tissue engineering strongly relies on the use of hydrogels as highly hydrated 3D matrices to support the maturation of laden cells. However, because of the lack of microarchitecture and sufficient porosity, common hydrogel systems do not provide physical cell-instructive guidance cues and efficient transport of nutrients and oxygen to the inner part of the construct. A controlled, organized cellular alignment and resulting alignment of secreted ECM are hallmarks of muscle, tendons, and nerves and play an important role in determining their functional properties. Although several strategies to induce cellular alignment have been investigated in 2D systems, the generation of cell-instructive 3D hydrogels remains a challenge. Here, we report on the development of a simple and scalable method to efficiently generate highly macroporous constructs featuring aligned guidance cues. A precross-linked bulk hydrogel is pressed through a grid with variable opening sizes, thus deconstructing it into an array of aligned, high aspect ratio microgels (microstrands) with tunable diameter that are eventually stabilized by a second photoclick cross-linking step. This method has been investigated and optimized both in silico and in vitro, thereby leading to conditions with excellent viability and organized cellular alignment. Finally, as proof of concept, the method has been shown to direct aligned muscle tissue maturation. These findings demonstrate the 3D physical guidance potential of our system, which can be used for a variety of anisotropic tissues and applications.

Stem Cell-Laden Hydrogel-Based 3D Bioprinting for Bone and Cartilage Tissue Engineering

Tremendous advances in tissue engineering and regenerative medicine have revealed the potential of fabricating biomaterials to solve the dilemma of bone and articular defects by promoting osteochondral and cartilage regeneration. Three-dimensional (3D) bioprinting is an innovative fabrication technology to precisely distribute the cell-laden bioink for the construction of artificial tissues, demonstrating great prospect in bone and joint construction areas. With well controllable printability, biocompatibility, biodegradability, and mechanical properties, hydrogels have been emerging as an attractive 3D bioprinting material, which provides a favorable biomimetic microenvironment for cell adhesion, orientation, migration, proliferation, and differentiation. Stem cell-based therapy has been known as a promising approach in regenerative medicine; however, limitations arise from the uncontrollable proliferation, migration, and differentiation of the stem cells and fortunately could be improved after stem cells were encapsulated in the hydrogel. In this review, our focus was centered on the characterization and application of stem cell-laden hydrogel-based 3D bioprinting for bone and cartilage tissue engineering. We not only highlighted the effect of various kinds of hydrogels, stem cells, inorganic particles, and growth factors on chondrogenesis and osteogenesis but also outlined the relationship between biophysical properties like biocompatibility, biodegradability, osteoinductivity, and the regeneration of bone and cartilage. This study was invented to discuss the challenge we have been encountering, the recent progress we have achieved, and the future perspective we have proposed for in this field.

Advanced Materials and Sensors for Microphysiological Systems: Focus on Electronic and Electrooptical Interfaces

Advanced in vitro cell culture systems or microphysiological systems (MPSs), including microfluidic organ-on-a-chip (OoC), are breakthrough technologies in biomedicine. These systems recapitulate features of human tissues outside of the body. They are increasingly being used to study the functionality of different organs for applications such as drug evolutions, disease modeling, and precision medicine. Currently, developers and endpoint users of these in vitro models promote how they can replace animal models or even be a better ethically neutral and humanized alternative to study pathology, physiology, and pharmacology. Although reported models show a remarkable physiological structure and function compared to the conventional 2D cell culture, they are almost exclusively based on standard passive polymers or glass with none or minimal real-time stimuli and readout capacity. The next technology leap in reproducing in vivo-like functionality and real-time monitoring of tissue function could be realized with advanced functional materials and devices. This review describes the currently reported electronic and optical advanced materials for sensing and stimulation of MPS models. In addition, an overview of multi-sensing for Body-on-Chip platforms is given. Finally, one gives the perspective on how advanced functional materials could be integrated into in vitro systems to precisely mimic human physiology.

Luciferin-Bioinspired Click Ligation Enables Hydrogel Platforms with Fine-Tunable Properties for 3D Cell Culture

There is an increasing interest in coupling reactions for cross-linking of cell-encapsulating hydrogels under biocompatible, chemoselective, and tunable conditions. Inspired by the biosynthesis of luciferins in fireflies, here we exploit the cyanobenzothiazole-cysteine (CBT-Cys) click ligation to develop polyethylene glycol hydrogels as tunable scaffolds for cell encapsulation. Taking advantage of the chemoselectivity and versatility of CBT-Cys ligation, a highly flexible gel platform is reported here. We demonstrate luciferin-inspired hydrogels with important advantages for cell encapsulation applications: (i) gel precursors derived from inexpensive reagents and with good stability in aqueous solution (>4 weeks), (ii) adjustable gel mechanics within physiological ranges (E = 180-6240 Pa), (iii) easy tunability of the gelation rate (seconds to minutes) by external means, (iv) high microscale homogeneity, (v) good cytocompatibility, and (iv) regulable biological properties. These flexible and robust CBT-Cys hydrogels are proved as supportive matrices for 3D culture of different cell types, namely, fibroblasts and human mesenchymal stem cells. Our findings expand the toolkit of click chemistries for the fabrication of tunable biomaterials.

Controlling Properties and Functions of Polymer Gels Using Photochemical Reactions

Photoresponsive polymer gels have attracted increasing interest owing to their potential applications in healable materials, drug release systems, and extracellular matrices. Because polymer gels provide suitable environments for photochemical reactions, their properties and functions can be controlled with light with a high spatiotemporal resolution. Herein, the design of photoresponsive polymer gels based on different types of photochemical reactions is introduced. The mechanism and applications of irreversible photoreactions, such as photoinduced free-radical polymerization, photoinduced click reactions, and photolysis, as well as reversible photoreactions such as photoinduced reversible cycloadditions, reversible photosubstitution of metal complexes, and photoinduced metathesis are reviewed. The remaining challenges of photoresponsive polymer gels are also discussed.

Tissue Engineering with Mechanically Induced Solid-Fluid Transitions

Epithelia are contiguous sheets of cells that stabilize the shape of internal organs and support their structure by covering their surfaces. They acquire diverse morphological forms appropriate for their specific functions during embryonic development, such as the kidney tubules and the complex branching structures found in the lung. The maintenance of epithelial morphogenesis and homeostasis is controlled by their remarkable mechanics-epithelia can become elastic, plastic, and viscous by actively remodeling cell-cell junctions and modulating the distribution of local stresses. Microfabrication, finite element modelling, light-sheet microscopy, and robotic micromanipulation are used to show that collagen gels covered with an epithelial skin serve as shape-programmable soft matter. The process involves solid to fluid transitions induced by mechanical perturbations, generates spatially distributed surface stresses at tissue interfaces, and is amenable to both additive and subtractive manufacturing techniques. The robustness and versatility of this strategy for engineering designer tissues is demonstrated by directing the morphogenesis of a variety of molded, carved, and assembled forms from the base material. The results provide insight into the active mechanical properties of the epithelia and establish methods for engineering tissues with sustainable architectures.

Highly photosensitive furan acrylate derivatives and their solid-state photopolymerization

Highly photosensitive multifunctional furan acrylate monomers synthesized from biomass furfural can be photopolymerized into polyesters without photoinitiators and solvents.

Towards organoid culture without Matrigel

Organoids-cellular aggregates derived from stem or progenitor cells that recapitulate organ function in miniature-are of growing interest in developmental biology and medicine. Organoids have been developed for organs and tissues such as the liver, gut, brain, and pancreas; they are used as organ surrogates to study a wide range of questions in basic and developmental biology, genetic disorders, and therapies. However, many organoids reported to date have been cultured in Matrigel, which is prepared from the secretion of Engelbreth-Holm-Swarm mouse sarcoma cells; Matrigel is complex and poorly defined. This complexity makes it difficult to elucidate Matrigel-specific factors governing organoid development. In this review, we discuss promising Matrigel-free methods for the generation and maintenance of organoids that use decellularized extracellular matrix (ECM), synthetic hydrogels, or gel-forming recombinant proteins.

Increasing the Microfabrication Performance of Synthetic Hydrogel Precursors through Molecular Design

Implementation of hydrogel precursors in two-photon polymerization (2PP) technology provides promising opportunities in the tissue engineering field thanks to their soft characteristics and similarity to extracellular matrix. Most of the hydrogels, however, are prone to post-fabrication deformations, leading to a mismatch between the computer-aided design and the printed structure. In the present work, we have developed novel synthetic hydrogel precursors to overcome the limitations associated with 2PP processing of conventional hydrogel precursors such as post-processing deformations and a narrow processing window. The precursors are based on a poly(ethylene glycol) backbone containing urethane linkers and are, on average, functionalized with six acrylate terminal groups (three on each terminal group). As a benchmark material, we exploited a precursor with an identical backbone and urethane linkers, albeit functionalized with two acrylate groups, that were reported as state-of-the-art. An in-depth characterization of the hexafunctional precursors revealed a reduced swelling ratio (<0.7) and higher stiffness (>36 MPa Young's modulus) compared to their difunctional analogs. The superior physical properties of the newly developed hydrogels lead to 2PP-based fabrication of stable microstructures with excellent shape fidelity at laser scanning speeds up to at least 90 mm s^-1, in contrast with the distorted structures of conventional difunctional precursors. The hydrogel films and microscaffolds revealed a good cell interactivity after functionalization of their surface with a gelatin methacrylamide-based coating. The proposed synthesis strategy provides a one-pot and scalable synthesis of hydrogel building blocks that can overcome the current limitations associated with 2PP fabrication of hydrogel microstructures.

Modulation of hydrogel stiffness by external stimuli: soft materials for mechanotransduction studies

Mechanotransduction is an important process in determining cell survival, proliferation, migration and differentiation. The extracellular matrix (ECM) is the component of natural tissue that provides structural support and biochemical signals to adhering cells. The ECM is dynamic and undergoes physical and biochemical changes in response to various stimuli and there is an interest in understanding the effect of dynamic changes in stiffness on cell behaviour and fate. Therefore, stimuli-responsive hydrogels have been developed to mimic the cells' microenvironment in a controlled fashion. Herein, we review strategies for dynamic modulation of stiffness using various stimuli, such as light, temperature and pH. Special emphasis is placed on conducting polymer (CP) hydrogels and their fabrication procedures. We believe that the redox properties of CPs and hydrogels' biological properties make CPs hydrogels a promising substrate to investigate the effect of dynamic stiffness changes and mechanical actuation on cell fate in future studies.

Self-Assembling Hydrogel Structures for Neural Tissue Repair

Hydrogel materials have been employed as biological scaffolds for tissue regeneration across a wide range of applications. Their versatility and biomimetic properties make them an optimal choice for treating the complex and delicate milieu of neural tissue damage. Aside from finely tailored hydrogel properties, which aim to mimic healthy physiological tissue, a minimally invasive delivery method is essential to prevent off-target and surgery-related complications. The specific class of injectable hydrogels termed self-assembling peptides (SAPs), provide an ideal combination of in situ polymerization combined with versatility for biofunctionlization, tunable physicochemical properties, and high cytocompatibility. This review identifies design criteria for neural scaffolds based upon key cellular interactions with the neural extracellular matrix (ECM), with emphasis on aspects that are reproducible in a biomaterial environment. Examples of the most recent SAPs and modification methods are presented, with a focus on biological, mechanical, and topographical cues. Furthermore, SAP electrical properties and methods to provide appropriate electrical and electrochemical cues are widely discussed, in light of the endogenous electrical activity of neural tissue as well as the clinical effectiveness of stimulation treatments. Recent applications of SAP materials in neural repair and electrical stimulation therapies are highlighted, identifying research gaps in the field of hydrogels for neural regeneration.

Multiphoton Laser Fabrication of Hybrid Photo-Activable Biomaterials

The possibility to shape stimulus-responsive optical polymers, especially hydrogels, by means of laser 3D printing and ablation is fostering a new concept of “smart” micro-devices that can be used for imaging, thermal stimulation, energy transducing and sensing. The composition of these polymeric blends is an essential parameter to tune their properties as actuators and/or sensing platforms and to determine the elasto-mechanical characteristics of the printed hydrogel. In light of the increasing demand for micro-devices for nanomedicine and personalized medicine, interest is growing in the combination of composite and hybrid photo-responsive materials and digital micro-/nano-manufacturing. Existing works have exploited multiphoton laser photo-polymerization to obtain fine 3D microstructures in hydrogels in an additive manufacturing approach or exploited laser ablation of preformed hydrogels to carve 3D cavities. Less often, the two approaches have been combined and active nanomaterials have been embedded in the microstructures. The aim of this review is to give a short overview of the most recent and prominent results in the field of multiphoton laser direct writing of biocompatible hydrogels that embed active nanomaterials not interfering with the writing process and endowing the biocompatible microstructures with physically or chemically activable features such as photothermal activity, chemical swelling and chemical sensing.

3D electron-beam writing at sub-15 nm resolution using spider silk as a resist

Electron beam lithography (EBL) is renowned to provide fabrication resolution in the deep nanometer scale. One major limitation of current EBL techniques is their incapability of arbitrary 3d nanofabrication. Resolution, structure integrity and functionalization are among the most important factors. Here we report all-aqueous-based, high-fidelity manufacturing of functional, arbitrary 3d nanostructures at a resolution of sub-15 nm using our developed voltage-regulated 3d EBL. Creating arbitrary 3d structures of high resolution and high strength at nanoscale is enabled by genetically engineering recombinant spider silk proteins as the resist. The ability to quantitatively define structural transitions with energetic electrons at different depths within the 3d protein matrix enables polymorphic spider silk proteins to be shaped approaching the molecular level. Furthermore, genetic or mesoscopic modification of spider silk proteins provides the opportunity to embed and stabilize physiochemical and/or biological functions within as-fabricated 3d nanostructures. Our approach empowers the rapid and flexible fabrication of heterogeneously functionalized and hierarchically structured 3d nanocomponents and nanodevices, offering opportunities in biomimetics, therapeutic devices and nanoscale robotics.

Nano-3D-Printed Photochromic Micro-Objects

Molecular photoswitches that can reversibly change color upon irradiation are promising materials for applications in molecular actuation and photoresponsive materials. However, the fabrication of photochromic devices is limited to conventional approaches such as mold casting and spin-coating, which cannot fabricate complex structures. Reported here is the first photoresist for direct laser writing of photochromic 3D micro-objects via two-photon polymerization. The integration of photochromism into thiol-ene photo-clickable resins enables rapid two-photon laser processing of highly complex microstructures and facile postmodification using a series of donor-acceptor Stenhouse adduct (DASA) photoswitches with different excitation wavelengths. The versatility of thiol-ene photo-click reactions allows fine-tuning of the network structure and physical properties as well as the type and concentration of DASA. When exposed to visible light, these microstructures exhibit excellent photoresponsiveness and undergo reversible color-changing via photoisomerization. It is demonstrated that the fluorescence variations of DASAs can be used as a reporter of photoswitching and thermal recovery, allowing the reading of DASA-containing sub-micrometric structures in 3D. This work delivers a new approach for custom microfabrication of 3D photochromic objects with molecularly engineered color and responsiveness.

Structurally Dynamic Hydrogels for Biomedical Applications: Pursuing a Fine Balance between Macroscopic Stability and Microscopic Dynamics

Owing to their unique chemical and physical properties, hydrogels are attracting increasing attention in both basic and translational biomedical studies. Although the classical hydrogels with static networks have been widely reported for decades, a growing number of recent studies have shown that structurally dynamic hydrogels can better mimic the dynamics and functions of natural extracellular matrix (ECM) in soft tissues. These synthetic materials with defined compositions can recapitulate key chemical and biophysical properties of living tissues, providing an important means to understanding the mechanisms by which cells sense and remodel their surrounding microenvironments. This review begins with the overall expectation and design principles of dynamic hydrogels. We then highlight recent progress in the fabrication strategies of dynamic hydrogels including both degradation-dependent and degradation-independent approaches, followed by their unique properties and use in biomedical applications such as regenerative medicine, drug delivery, and 3D culture. Finally, challenges and emerging trends in the development and application of dynamic hydrogels are discussed.

Thiol-Methylsulfone-Based Hydrogels for Cell Encapsulation: Reactivity Optimization of Aryl-Methylsulfone Substrate for Fine-Tunable Gelation Rate and Improved Stability

Hydrogels are widely used as hydrated matrices for cell encapsulation in a number of applications, spanning from advanced 3D cultures and tissue models to cell-based therapeutics and tissue engineering. Hydrogel formation in the presence of living cells requires cross-linking reactions that proceed efficiently under close to physiological conditions. Recently, the nucleophilic aromatic substitution of phenyl-oxadiazole (Ox) methylsulfones (MS) by thiols was introduced as a new cross-linking reaction for cell encapsulation. Reported poly(ethylene glycol) (PEG)-based hydrogels featured tunable gelation times within seconds to a few minutes within pH 8.0 to 6.6 and allowed reasonably good mixing with cells. However, their rapid degradation prevented cell cultures to be maintained beyond 1 week. In this Article, we present the reactivity optimization of the heteroaromatic ring of the MS partner to slow down the cross-linking kinetics and the degradability of the derived hydrogels. New MS substrates based on phenyl-tetrazole (Tz) and benzothiazole (Bt) rings, with lower electrophilicity than Ox, were synthesized by simple pathways. When mixed with PEG-thiol, the novel PEG-MS extended the working time of precursor mixtures and allowed longer term cell culture. The Tz-based MS substrate was identified as the best candidate, as it is accessible by simple chemical reactions from cost-effective reactants, hydrogel precursors show good stability in aqueous solution and keep high chemoselectivity for thiols, and the derived Tz gels support cell cultures for >2 weeks. The Tz system also shows tunable gelation kinetics within seconds to hours and allows comfortable manipulation and cell encapsulation. Our findings expand the toolkit of thiol-mediated chemistry for the synthesis of hydrogels with improved properties for laboratory handling and future automatization.

Hydrogel-based diffractive optical elements (hDOEs) using rapid digital photopatterning

Hydrogels, due to their optical transparency and biocompatibility, have emerged as an excellent alternative to conventional optical materials for biomedical applications. Advances in microfabrication techniques have helped convert conventional hydrogels into optically functional materials such as hydrogel-based diffraction optical elements (hDOEs). However, key challenges related to device customization and ease/speed of fabrication need to be addressed to enable widespread utility and acceptance of hDOEs in the field. Here, we report rapid printing of customized hDOEs on polyethylene glycol diacrylate (PEGDA) hydrogel using digital photopatterning; a novel method that combines simulated computer-generated hologram (SCGH) and projection photolithography. To showcase the versatility of this approach, a range of hDOEs are demonstrated, including 1D/2D diffraction gratings, Dammann grating, Fresnel zone plate (FZP) lens, fork-shaped grating and computer-generated hologram (CGH) of arbitrary pattern. Results demonstrate that printed hDOEs exhibit optical performance that is comparable with devices made with conventional materials. This versatile strategy can be potentially implemented with other photosensitive hydrogels to achieve user-defined hDOEs in a time-efficient and cost-effective fashion.

Fabricating poly(vinyl alcohol)/gelatin composite sponges with high absorbency and water-triggered expansion for noncompressible hemorrhage and wound healing

Composite sponges obtained from PVA and gelatin were synthesized by thiol–ene chemistry and used for controlling noncompressible hemorrhage.

Multistimuli-Responsive Optical Hydrogel Nanomembranes to Construct Planar Color Display Boards for Detecting Local Environmental Changes

Planar metal-insulator-metal (MIM) optical cavities are attractive for biochemical and environmental sensing applications, as they offer a cost-effective cavity platform with acceptable performances. However, localized detection and scope of expansion of applicable analytes are still challenging. Here, we report a stimuli-responsive color display board that can exhibit local spectral footprints, for locally applied heat and alcohol presence. A thermoresponsive, optically applicable, and patternable copolymer, poly(N-isopropylacrylamide-r-glycidyl methacrylate), is synthesized and used with a photosensitive cross-linker to produce a responsive insulating layer. This layer is then sandwiched between two nanoporous silver membranes to yield a thermoresponsive MIM cavity. The resonant spectral peak is blue-shifted as the environmental temperature increases, and the dynamic range of the resonant peak is largely affected by the composition and structure of the cross-linker and the copolymer. The localized temperature increase of silk particles with gold nanoparticles by laser heating can be measured by reading the spectral shift. In addition, a free-standing color board can be transferred onto a curved biological tissue sample, allowing us to simultaneously read the temperature of the tissue sample and the concentration of ethanol. The stimuli-responsive MIM provides a new way to optically sense localized environmental temperature and ethanol concentration fluctuations.

Composition and Mechanism of Three-Dimensional Hydrogel System in Regulating Stem Cell Fate

Three-dimensional (3D) hydrogel systems integrating different types of stem cells and scaffolding biomaterials have an important application in tissue engineering. The biomimetic hydrogels that pattern cell suspensions within 3D configurations of biomaterial networks allow for the transport of bioactive factors and mimic the stem cell niche in vivo, thereby supporting the proliferation and differentiation of stem cells. The composition of a 3D hydrogel system determines the physical and chemical characteristics that regulate stem cell function through a biological mechanism. Here, we discuss the natural and synthetic hydrogel compositions that have been employed in 3D scaffolding, focusing on their characteristics, fabrication, biocompatibility, and regulatory effects on stem cell proliferation and differentiation. We also discuss the regulatory mechanisms of cell-matrix interaction and cell-cell interaction in stem cell activities in various types of 3D hydrogel systems. Understanding hydrogel compositions and their cellular mechanisms can yield insights into how scaffolding biomaterials and stem cells interact and can lead to the development of novel hydrogel systems of stem cells in tissue engineering and stem cell-based regenerative medicine. Impact statement Three-dimensional hydrogel system of stem cell mimicking the stemcell niche holds significant promise in tissue engineering and regenerative medicine. Exactly how hydrogel composition regulates stem cell fate is not well understood. This review focuses on the composition of hydrogel, and how the hydrogel composition and its properties regulate the stem cell adhesion, growth, and differentiation. We propose that cell-matrix interaction and cell-cell interaction are important regulatory mechanisms in stem cell activities. Our review provides key insights into how the hydrogel composition regulates the stem cell fate, untangling the engineering of three-dimensional hydrogel systems for stem cells.

Organoid Polymer Functionality and Mode of Klebsiella Pneumoniae Membrane Antigen Presentation Regulates Ex Vivo Germinal Center Epigenetics in Young and Aged B Cells

Antibiotic-resistant bacteria are a major global health threat that continues to rise due to a lack of effective vaccines. Of concern are Klebsiella pneumoniae that fail to induce in vivo germinal center B cell responses, which facilitate antibody production to fight infection. Immunotherapies using antibodies targeting antibiotic-resistant bacteria are emerging as promising alternatives, however, they cannot be efficiently derived ex vivo, necessitating the need for immune technologies to develop therapeutics. Here, PEG-based immune organoids were developed to elucidate the effects of polymer end-point chemistry, integrin ligands, and mode of K. pneumoniae antigen presentation on germinal center-like B cell phenotype and epigenetics, to better define the lymph node microenvironment factors regulating ex vivo germinal center dynamics. Notably, PEG vinyl sulfone or acrylate failed to sustain primary immune cells, but functionalization with maleimide (PEG-4MAL) led to B cell expansion and germinal center-like induction. RNA sequencing analysis of lymph node stromal and germinal center B cells showed niche associated heterogeneity of integrin-related genes. Incorporation of niche-mimicking peptides revealed that collagen-1 promoted germinal center-like dynamics and epigenetics. PEG-4MAL organoids elucidated the impact of K. pneumoniae outer membrane-embedded protein antigen versus soluble antigen presentation on germinal centers and preserved the response across young and aged mice.

Synthesis of photocrosslinkable hydrogels for engineering three-dimensional vascular-like constructs by surface tension-driven assembly

Surface tension-driven assembly is a simple routine used in modular tissue engineering to create three-dimensional (3D) biomimetic tissues with desired structural and biological characteristics. A major bottleneck for this technology is the lack of suitable hydrogel materials to meet the requirements of the assembly process and tissue regeneration. Identifying specific requirements and synthesizing novel hydrogels will provide a versatile platform for generating additional biomimetic functional tissues using this approach. In this paper, we present a novel composite hydrogel system based on methacrylated gelatin and γ-polyglutamic acid by UV copolymerization as the building block for fabricating vascular-like tissue via surface tension-driven assembly. The resulting composite hydrogels exhibited the improved mechanical properties and hydrophilicity, which greatly facilitate the assembly process. Subsequent cell encapsulation experiment proved that the hydrogel could provide 3D support for cellular spreading and migration. Furthermore, based on the composite microgel building blocks, cylindrical vascular-like construct with a perfusable microchannel was generated by the needle-assisted sequential assembly. In order to construct a biomimetic vascular tissue, the endothelial cells and smooth muscle cells were encapsulated in the microgels assembly with a spatial arrangement to build a heterogeneous double-layer tubular structure and the cells could readily elongate and migrate in the hollow concentric construct over 3 days. These data suggest that this composite hydrogel is an attractive candidate for surface tension-driven assembly purposes, making the hydrogel potentially applicable in the fabrication of biomimetic vascularized tissues.

Spatiotemporally Controlled Photoresponsive Hydrogels: Design and Predictive Modeling from Processing through Application

Photoresponsive hydrogels (PRHs) are soft materials whose mechanical and chemical properties can be tuned spatially and temporally with relative ease. Both photo-crosslinkable and photodegradable hydrogels find utility in a range of biomedical applications that require tissue-like properties or programmable responses. Progress in engineering with PRHs is facilitated by the development of theoretical tools that enable optimization of their photochemistry, polymer matrices, nanofillers, and architecture. This review brings together models and design principles that enable key applications of PRHs in tissue engineering, drug delivery, and soft robotics, and highlights ongoing challenges in both modeling and application.

Spheroids of Endothelial Cells and Vascular Smooth Muscle Cells Promote Cell Migration in Hyaluronic Acid and Fibrinogen Composite Hydrogels

Cell migration plays a pivotal role in many pathological and physiological processes. So far, most of the studies have been focused on 2-dimensional cell adhesion and migration. Herein, the migration behaviors of cell spheroids in 3D hydrogels obtained by polymerization of methacrylated hyaluronic acid (HA-MA) and fibrinogen (Fg) with different ratios were studied. The Fg could be released to the medium gradually along with time prolongation, achieving the dynamic change of hydrogel structures and properties. Three types of cell spheroids, i.e., endothelial cell (EC), smooth muscle cell (SMC), and EC-SMC spheroids, were prepared with 10,000 cells in each, whose diameters were about 343, 108, and 224 μm, respectively. The composite hydrogels with an intermediate ratio of Fg allowed the fastest 3D migration of cell spheroids. The ECs-SMCs migrated longest up to 3200 μm at day 14, whereas the SMC spheroids migrated slowest with a distance of only ~400 μm at the same period of time. The addition of free RGD or anti-CD44 could significantly reduce the migration distance, revealing that the cell-substrate interactions take the major roles and the migration is mesenchymal dependent. Moreover, addition of anti-N-cadherin and MMP inhibitors also slowed down the migration rate, demonstrating that the degradation of hydrogels and cell-cell interactions are also largely involved in the cell migration. RT-PCR measurement showed that expression of genes related to cell adhesion and antiapoptosis, and angiogenesis was all upregulated in the EC-SMC spheroids than single EC or SMC spheroids, suggesting that the use of composite cell spheroids is more promising to promote cell-substrate interactions and maintenance of cell functions.

Thiol-Methylsulfone-Based Hydrogels for 3D Cell Encapsulation

Thiol-maleimide and thiol-vinylsulfone cross-linked hydrogels are widely used systems in 3D culture models, in spite of presenting uncomfortable reaction kinetics for cell encapsulation: too fast (seconds for thiol-maleimide) or too slow (minutes-hours for thiol-vinylsulfone). Here, we introduce the thiol-methylsulfone reaction as alternative cross-linking chemistry for cell encapsulation, particularized for PEG-hydrogels. The thiol-methylsulfone reaction occurs at high conversion and at intermediate reaction speed (seconds-minutes) under physiological pH range. These properties allow easy mixing of hydrogel precursors and cells to render homogeneous cell-laden gels at comfortable experimental time scales. The resulting hydrogels are cytocompatible and show comparable hydrolytic stability to thiol-vinylsulfone gels. They allow direct bioconjugation of thiol-derivatized ligands and tunable degradation kinetics by cross-linking with degradable peptide sequences. 3D cell culture of two cell types, fibroblasts and human umbilical vein endothelial cells (HUVECs), is demonstrated.

Creating Physicochemical Gradients in Modular Microporous Annealed Particle Hydrogels via a Microfluidic Method

Microporous annealed particle (MAP) hydrogels are an attractive platform for engineering biomaterials with controlled heterogeneity. Here, we introduce a microfluidic method to create physicochemical gradients within poly(ethylene glycol) based MAP hydrogels. By combining microfluidic mixing and droplet generator modules, microgels with varying properties were produced by adjusting the relative flow rates between two precursor solutions and collected layer-by-layer in a syringe. Subsequently, the microgels were injected out of the syringe and then annealed with thiol-ene click chemistry. Fluorescence intensity measurements of constructs annealed in vitro and after mock implantation into a tissue defect showed that a continuous gradient profile was achieved and maintained after injection, indicating utility for in situ hydrogel formation. The effects of physicochemical property gradients on human mesenchymal stem cells (hMSCs) were also studied. Microgel stiffness was studied first, and the hMSCs exhibited increased spreading and proliferation as stiffness increased along the gradient. Microgel degradability was also studied, revealing a critical degradability threshold above which the hMSCs spread robustly and below which they were isolated and exhibited reduced spreading. This method of generating spatial gradients in MAP hydrogels could be further used to gain new insights into cell-material interactions, which could be leveraged for tissue engineering applications. A new droplet microfluidic approach to obtain microporous annealed particle hydrogels with physicochemical gradients is presented. Gradient formation is achieved by precisely controlling the mixing of two precursor solutions, and the gradient can be maintained after injection. This approach can be leveraged to produce new materials for tissue repair and to gain unique insights on cell-material interactions.

Sustained protein therapeutics enabled by self-healing nanocomposite hydrogels for non-invasive bone regeneration

The self-healing nanocomposite hydrogel for sustained release of BMP-2 to enhance bone regeneration.

Near-infrared light-responsive hydrogels via peroxide-decorated MXene-initiated polymerization

Two-dimensional MXene Ti3C2T x nanosheets with peroxide decoration (p-Ti3C2T x ) are synthesized by a sonication-assisted MILD etching method. The obtained MXenes can generate hydroxyl radical species and act as an initiator for free-radical polymerization of a series of acrylic monomers without the use of light illumination or co-initiators. The monomers analyzed include acrylamide, N-isopropylacrylamide (NIPAM), N,N-dimethylacrylamide, methyl methacrylate, and hydroxyethyl methacrylate. By simply mixing N-isopropylacrylamide monomers and p-Ti3C2T x nanosheets under deoxygenated conditions, PNIPAM-based nanocomposite hydrogels are synthesized using a high concentration of the monomer. The nanocomposite hydrogels have a photothermal conversion efficiency of 34.7% and photothermal stability superior to that of pristine Ti3C2T x . Taking advantage of the thermal responsive behavior of PNIPAM, the nanocomposite hydrogels are successfully exploited as remotely near-infrared light controlled "smart" windows, fluidic valves and photodetectors.

Dynamic-Covalent Hydrogel with NIR-Triggered Drug Delivery for Localized Chemo-Photothermal Combination Therapy

Near-infrared (NIR) light-responsive, injectable hydrogels are among the most promising drug delivery systems for localized anticancer therapy owing to its minimally invasive administration and remote-controlled manner. However, most currently reported NIR-responsive hydrogels were usually generated through physical mixing of thermosensitive polymers and photothermal conversion agents. In this study, a novel type of dynamic-covalent hydrogel (GelPV-DOX-DBNP) with NIR light-triggered drug release behavior was rationally designed for chemo-photothermal combination treatment of tumors. Concretely, this NIR-responsive hydrogel was formed by specific benzoxaborole-carbohydrate interactions between benzoxaborole (BOB)-modified hyaluronic acid (BOB-HA) and fructose-based glycopolymer (PolyFru), where photosensitizer perylene diimide zwitterionic polymer (PDS), reductant ascorbic acid (Vc), anticancer drug doxorubicin (DOX) as well as photothermal nanoparticles (DB-NPs) were encapsulated, simultaneously. Upon 660 nm light irradiation, both PDS and Vc within the designed hydrogel can convert oxygen into hydrogen peroxide, which could make hydrogel be degraded through the breakage of dynamic covalent bonds based on benzoxaborole-carbohydrate interactions, leading to NIR light-activatable release of DOX and DB-NPs from GelPV-DOX-DBNP. Furthermore, the released DB-NPs can convert 915 nm light irradiation into heat, enabling the application of GelPV-DOX-DBNP as a NIR-responsive drug delivery platform for both chemotherapy and photothermal therapy (PTT). In vivo results prove that GelPV-DOX-DBNP exhibited a markedly enhanced chemo-photothermal synergistic therapy for 4T1 tumor model mice, compared to chemotherapy alone or PTT. This work presents a new strategy to construct NIR light-responsive hydrogel as one alternative drug delivery system for anticancer applications.

Photothermal-modulated reversible volume transition of wireless hydrogels embedded with redox-responsive carbon dots

The reversible volume transition of redox-responsive hydrogels by near-infrared (NIR) irradiation has recently attracted significant attention as a novel therapy matrix for tracking and treating cancer via stimuli-responsive fluorescence on/off with controllable volume transition via a wireless sensing system. Herein, a NIR-induced redox-sensitive hydrogel was synthesized by blending a hydrogel with IR825-loaded carbon dots (CD) to achieve enhanced mobility of nanoparticles inside a gel network, and reversible volume phase transitions remotely controlled by a smartphone application via the induction of different redox environments. The presence of CD-IR825 in the thermosensitive poly(N-isopropylacrylamide) hydrogel network imparted fluorescence, electronic and photothermal properties to the hydrogels, which resulted in volume shrinkage behavior of the hydrogel upon exposure to NIR laser irradiation due to the redox-sensitive CDs. Under the NIR on/off cycles, the photothermal temperature, fluorescence, and porous structure were reversed after turning off the NIR laser. The hydrogel responsiveness under GSH and NIR light was studied using a wireless device based on the changes in the resistance graph on a smartphone application, generating a fast and simple method for the investigation of hydrogel properties. The in vitro cell viabilities of the MDA-MB cancer cells incubated with the composite hydrogel in the presence of external GSH exhibited a higher photothermal temperature, and the cancer cells were effectively killed after the NIR irradiation. Therefore, the NIR-induced redox-responsive nanocomposite hydrogel prepared herein has potential for use in cancer treatment and will enable the study of nanoparticle motion in hydrogel networks under multiple stimuli via a wireless device using a faster and more convenient method.

Integration of biological systems with electronic-mechanical assemblies

Biological systems continuously interact with the surrounding environment because they are dynamically evolving. The interaction is achieved through mechanical, electrical, chemical, biological, thermal, optical, or a synergistic combination of these cues. To provide a fundamental understanding of the interaction, recent efforts that integrate biological systems with the electronic-mechanical assemblies create unique opportunities for simultaneous monitoring and eliciting the responses to the biological system. Recent innovations in materials, fabrication processes, and device integration approaches have created the enablers to yield bio-integrated devices to interface with the biological system, ranging from cells and tissues to organs and living individual. In this short review, we will provide a brief overview of the recent development on the integration of the biological systems with electronic-mechanical assemblies across multiple scales, with applications ranging from healthcare monitoring to therapeutic options such as drug delivery and rehabilitation therapies. STATEMENT OF SIGNIFICANCE: An overview of the recent progress on the integration of the biological system with both electronic and mechanical assemblies is discussed. The integration creates the unique opportunity to simultaneously monitor and elicit the responses to the biological system, which provides a fundamental understanding of the interaction between the biological system and the electronic-mechanical assemblies. Recent innovations in materials, fabrication processes, and device integration approaches have created the enablers to yield bio-integrated devices to interface with the biological system, ranging from cells and tissues to organs and living individual.

Multi-foci laser microfabrication of 3D polymeric scaffolds for stem cell expansion in regenerative medicine

High quality large scale fabrication of cellular scaffolds, with three-dimensional resolution comparable to cell size, is an important task to enable regenerative medicine applications with stem cells. We are using two-photon polymerization to produce our stem cell culture substrate called Nichoid, which we already demonstrated capable of stimulating cell proliferation while maintaining their stemness, without the need of dangerous additives. Parallelization of this technique can be achieved with the use of a spatial light modulator: here we show the results obtained combining this device with fast linear stages to produce Nichoid-covered substrates by two-photon polymerization. The well-polymerized structures confirm that this approach is particularly convenient for porous structures, and allows a significant time saving by a factor of almost five, with minor design adjustments. A Live & Dead assay was performed on mesenchymal stem cells cultured into the Nichoid microstructures in order to verify that no difference in cell viability is present, compared to microstructures fabricated by a single focus. This parallel setup opens the possibility to obtain a much larger number of microstructured substrates, that are essential to test new stem cell-based therapies. This approach can be also used for the fast fabrication of other kinds of cell culture devices.