Constructions, Purifications and Applications of DNA-Antibody Conjugates: A Review.

A DNA-antibody conjugate is a synthetic molecule that combines the unique functions of both an antibody and DNA. With the increased accessibility of commercialized kits, the procedure for constructing conjugates is simplified and the requirement for chemistry background is reduced. As a result, the difficulty of preparing a DNA-antibody conjugate has been significantly lowered.

Injectable acellular matrix microgel assembly with stem cell recruitment and chondrogenic differentiation functions promotes microfracture-based articular cartilage regeneration.

Articular cartilage repair and regeneration is still a significant challenge despite years of research. Although microfracture techniques are commonly used in clinical practice, the newborn cartilage is usually fibrocartilage rather than hyaline cartilage, which is mainly attributed to the inadequate microenvironment for effectively recruiting, anchoring, and inducing bone marrow mesenchymal stem cells (BMSCs) to differentiate into hyaline cartilage. This paper introduces a novel cartilage acellular matrix (CACM) microgel assembly with excellent microporosity, injectability, tissue adhesion, BMSCs recruitment and chondrogenic differentiation capabilities to improve the microfracture-based articular cartilage regeneration.

An injectable and degradable heterogeneous microgel assembly capable of forming a "micro-nest group" for cell condensation and cartilage regeneration.

Cell condensation, linking the migration and chondrogenic differentiation of MSCs, plays a crucial role in cartilage development. Current cartilage repair strategies are inadequately concerned with this process, leading to a suboptimal quality of regenerated cartilage. Inspired by the "nest flocks" structure of Social Weavers, a degradable heterogeneous microgel assembly (F/S-MA) is developed, which can release SDF-1, to form a "micro-nest group" structure and bond with HAV peptides to promote cell recruitment, condensation and chondrogenic differentiation.

Hemostatic Dressing Immobilized with ε-poly-L-lysine and Alginate Coated Mesoporous Bioactive Glass Prevents Blood Permeation by Pseudo-Dewetting Behavior.

The integration of hemostats with cotton fabrics is recognized as an effective approach to improve the hemostatic performance of dressings. However, concerns regarding the uncontrollable absorption of blood by hydrophilic dressings and the risk of distal thrombosis from shed hemostatic agents are increasingly scrutinized. To address these issues, this work develops an advanced dressing (AQG) with immobilized nano-scale mesoporous bioactive glass (MBG) to safely and durably augment hemostasis.

A Universal Strategy to Construct High-Performance Homo- and Heterogeneous Microgel Assembly Bioinks.

Three dimensional (3D) extrusion bioprinting aims to replicate the complex architectures and functions of natural tissues and organs. However, the conventional hydrogel and new-emerging microgel bioinks are both difficult in achieving simultaneously high shape-fidelity and good maintenance of cell viability/function, leading to limited amount of qualified hydrogel/microgel bioinks. Herein, a universal strategy is reported to construct high-performance microgel assembly (MA) bioinks by using epigallocatechin gallate-modified hyaluronic acid (HA-EGCG) as coating agent and phenylboronic acid grafted hyaluronic acid (HA-PBA) as assembling agent.

Engineering superstable islets-laden chitosan microgels with carboxymethyl cellulose coating for long-term blood glucose regulation in vivo.

Islet transplantation to restore endogenous insulin secretion is a promising therapy for type 1 diabetes in clinic. However, host immune rejection seriously limits the survival of transplanted islets. Despite of the various encapsulation strategies and materials developed so far to provide immune isolation for transplanted islets, long-term blood glucose regulation is still difficult due to the inherent defects of the encapsulation materials.

A novel bioartificial pancreas fabricated via islets microencapsulation in anti-adhesive core-shell microgels and macroencapsulation in a hydrogel scaffold prevascularized in vivo.

Islets transplantation is a promising treatment for type 1 diabetes mellitus. However, severe host immune rejection and poor oxygen/nutrients supply due to the lack of surrounding capillary network often lead to transplantation failure. Herein, a novel bioartificial pancreas is constructed via islets microencapsulation in core-shell microgels and macroencapsulation in a hydrogel scaffold prevascularized in vivo.

Injectable chondroitin sulfate-grafted self-antioxidant hydrogels ameliorate nucleus pulposus degeneration against overactive inflammation.

Overactive inflammatory cascade accompanied by oxidative stress in the nucleus pulposus exacerbates intervertebral disc degeneration (IVDD). Hydrogels have been demonstrated to be promising in treating IVDD, yet they remain less efficacious in the case of anti-inflammation associated with antioxidation. In this study, we designed an injectable self-antioxidant hydrogel (HA/CS) with enhanced inflammation inhibitory performance for delivering chondroitin sulfate (CS) with well-documented anti-inflammatory property to treat IVDD.

Wearable Dual-Signal NH Sensor with High Sensitivity for Non-invasive Diagnosis of Chronic Kidney Disease.

NH gas in human exhaled breath contains abundant physiological information related to human health, especially chronic kidney disease (CKD). Unfortunately, up to now, most wearable NH sensors show inevitable defects (low sensitivity, easy to be interfered by the environment, etc.), which may lead to misdiagnosis of CKD.

Injectable and tissue adhesive EGCG-laden hyaluronic acid hydrogel depot for treating oxidative stress and inflammation.

Oxidative stress and inflammation are common pathological mechanisms for the progression of tissue degeneration. Epigallocatechin-3-gallate (EGCG) features antioxidant and anti-inflammatory properties, which is a promising drug for the treatment of tissue degeneration. Herein, we utilize the phenylborate ester reaction of EGCG and phenylboronic acid (PBA) to fabricate an injectable and tissue adhesive EGCG-laden hydrogel depot (EGCG HYPOT), which can achieve anti-inflammatory and antioxidative effects via smart delivery of EGCG.

Co-transplantation of Islets-Laden Microgels and Biodegradable O-Generating Microspheres for Diabetes Treatment.

Pancreatic islets transplantation is an optimal alternative to exogenous insulin injection for long-term effective type 1 diabetes treatment. However, direct islets transplantation without any protection can induce cell necrosis due to severe host immune rejection. Insufficient O supply induced by the lack of capillary network at the early stage of islets transplantation is another critical constraint limiting islets survival and insulin-secretion function.

A versatile strategy to construct free-standing multi-furcated vessels and a complicated vascular network in heterogeneous porous scaffolds combination of 3D printing and stimuli-responsive hydrogels.

Mimicking complex structures of natural blood vessels and constructing vascular networks in tissue engineering scaffolds are still challenging now. Herein we demonstrate a new and versatile strategy to fabricate free-standing multi-furcated vessels and complicated vascular networks in heterogeneous porous scaffolds by integrating stimuli-responsive hydrogels and 3D printing technology. Through the sol-gel transition of temperature-responsive gelatin and conversion between two physical crosslinking networks of pH-responsive chitosan (, electrostatic network between protonated chitosan and sulfate ion, crystalline network of neutral chitosan), physiologically-stable gelatin/chitosan hydrogel tubes can be constructed.

Porous and conductive cellulose nanofiber/carbon nanotube foam as a humidity sensor with high sensitivity.

In this study, we developed a humidity sensor with high sensitivity based on cellulose nanofiber/carbon nanotube (CNF/CNT) hybrid foam. The porous structure of the foam not only provides more contact interface for water molecules adsorption, but also tunes the conductivity of the CCF closed to the point where the sensor is most sensitive to the change in humidity. With this porous structural design, the obtained foam sensor shows a high humidity sensitivity of 87.

A Three-Dimensional-Printed Recyclable, Flexible, and Wearable Device for Visualized UV, Temperature, and Sweat pH Sensing.

Wearable devices are now recognized as a powerful tool to collect physiological and environmental information in a smart, noninvasive, and real-time manner. Despite the rapid progress of wearable devices especially wearable electronic devices, there are still several challenges that limit their further development, for example, a complicated electrical signal acquisition and processing process to eliminate the interference from the surrounding signals, bulky power supply, inevitable e-waste, and environmental pollution. Herein, we report a 3D-printed recyclable, flexible, and wearable device for visualized UV, temperature, and sweat pH sensing.

Assembling Microgels via Dynamic Cross-Linking Reaction Improves Printability, Microporosity, Tissue-Adhesion, and Self-Healing of Microgel Bioink for Extrusion Bioprinting.

Extrusion bioprinting has been widely used to fabricate complicated and heterogeneous constructs for tissue engineering and regenerative medicine. Despite the remarkable progress acquired so far, the exploration of qualified bioinks is still challenging, mainly due to the conflicting requirements on the printability/shape-fidelity and cell viability. Herein, a new strategy is proposed to formulate a dynamic cross-linked microgel assembly (DC-MA) bioink, which can achieve both high printability/shape-fidelity and high cell viability by strengthening intermicrogel interactions through dynamic covalent bonds while still maintaining the relatively low mechanical modulus of microgels.

In Situ Formation of Microgel Array Via Patterned Electrospun Nanofibers Promotes 3D Cell Culture and Drug Testing in a Microphysiological System.

A microphysiological system (MPS) is recently emerging as a promising alternative to the classical preclinical models, especially animal testing. A key factor for the construction of MPS is to provide a biomimetic three-dimensional (3D) cellular microenvironment. However, it still remains a challenge to introduce extracellular matrix (ECM)-like biomaterials such as hydrogels and nanofibers in a precise and spatiotemporal manner.

Dynamic Nanocomposite Microgel Assembly with Microporosity, Injectability, Tissue-Adhesion, and Sustained Drug Release Promotes Articular Cartilage Repair and Regeneration.

Owing to the lack of blood vessels, nerves, and lymph, articular cartilage defect is difficult to self-repair. Although several cartilage tissue engineering products have been authorized for clinical use, there are still some problems such as large surgical wounds, weak adhesion with the host tissue, and the limited source of autologous chondrocytes. In this paper, a novel dynamic nanocomposite microgel assembly with excellent microporosity, injectability, tissue-adhesion, and sustained kartogenin (KGN) release is reported.

Microgel assembly: Fabrication, characteristics and application in tissue engineering and regenerative medicine.

Microgel assembly, a macroscopic aggregate formed by bottom-up assembly of microgels, is now emerging as prospective biomaterials for applications in tissue engineering and regenerative medicine (TERM). This mini-review first summarizes the fabrication strategies available for microgel assembly, including chemical reaction, physical reaction, cell-cell interaction and external driving force, then highlights its unique characteristics, such as microporosity, injectability and heterogeneity, and finally itemizes its applications in the fields of cell culture, tissue regeneration and biofabrication, especially 3D printing. The problems to be addressed for further applications of microgel assembly are also discussed.

Facile Fabrication of Hollow Hydrogel Microfiber via 3D Printing-Assisted Microfluidics and Its Application as a Biomimetic Blood Capillary.

Simulating the structure and function of blood capillaries is very important for an in-depth insight into their role in the human body and treatment of capillary-related diseases. Due to the similar composition and structure, hollow hydrogel microfibers are well-recognized as potential biomimetic blood capillaries. In this paper, we report a novel, facile, and reproducible method to fabricate coaxial microfluidic chips via 3D printing-assisted soft lithography and then hollow hydrogel microfibers using the as-prepared coaxial microfluidic chips.

3D printing of Cu-doped bioactive glass composite scaffolds promotes bone regeneration through activating the HIF-1α and TNF-α pathway of hUVECs.

The increasing insight into the molecular and cellular processes within the angiogenic cascade assists in enhancing the survival and integration of engineered bone constructs. Copper-doped bioactive glass (Cu-BG) is now a potential structural component of the novel scaffolds and implants used in orthopedic and dental repairs. However, it is difficult for BG, especially micro-nano particles, to be printed into scaffolds and still retain its biological activity and ability to biodegrade.

3D printed silk-gelatin hydrogel scaffold with different porous structure and cell seeding strategy for cartilage regeneration.

Hydrogel scaffolds are attractive for tissue defect repair and reorganization because of their human tissue-like characteristics. However, most hydrogels offer limited cell growth and tissue formation ability due to their submicron- or nano-sized gel networks, which restrict the supply of oxygen, nutrients and inhibit the proliferation and differentiation of encapsulated cells. In recent years, 3D printed hydrogels have shown great potential to overcome this problem by introducing macro-pores within scaffolds.

Tubular Silk Fibroin/Gelatin-Tyramine Hydrogel with Controllable Layer Structure and Its Potential Application for Tissue Engineering.

In recent years, biomimetic tubular scaffolds have been widely used to repair various human tissue defects, due to their hollow structure similar to the native tissues such as blood vessel, trachea, ureter, and bone marrow cavity. However, there are still many challenges in manufacturing a tubular hydrogel scaffold with suitable mechanical properties, specific microstructure, and good biocompatibility. In this study, we exploited an enzymatic cross-linking method using horseradish peroxidase (HRP) as an enzyme and hydrogen peroxide (HO) as a substrate, and combining with gelatin's thermal sensitivity to produce an enzymatically cross-linked silk fibroin/gelatin-tyramine (E-SF/GT) tubular hydrogel.

Electrostatic self-assembly enabled flexible paper-based humidity sensor with high sensitivity and superior durability.

Humidity sensors have been widely used for humidity monitoring in industrial fields. However, the application of conventional sensors is limited due to the structural rigidity, high cost, and time-consuming integration process. Owing to the good hydrophilicity, biodegradability, and low cost of cellulose, the sensors built on cellulose bulk materials are considered a feasible method to overcome these drawbacks while providing reasonable performance.

Engineering the cellular mechanical microenvironment to regulate stem cell chondrogenesis: Insights from a microgel model.

Biophysical cues (especially mechanical cues) embedded in cellular microenvironments show a critical impact on stem cell fate. Despite the capability of traditional hydrogels to mimic the feature of extracellular matrix (ECM) and tune their physicochemical properties via diverse approaches, their relatively large size not only induces biased results, but also hinders high-throughput screening and analysis. In this paper, a microgel model is proposed to recapitulate the role of 3D mechanical microenvironment on stem cell behaviors especially chondrogenesis in vitro.