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This study investigates microstructure, hydrogen diffusion properties, and stress corrosion cracking (SCC) behavior of Q345R steel subject to pre-applied strains of 1 %, 3 %, and 5 %. The relationship between microstructure and SCC susceptibility in hydrofluoric acid (HF) vapor is examined. It is found that pre-strain cannot change the microstructure of Q345R steel but increases dislocation density. The increasing SCC sensitivity of Q345R steel in HF vapor is associated with the dislocation density induced by pre-strain. With increasing pre-strain, dislocation density and reversible hydrogen trap increase, and interaction between hydrogen and dislocation accelerates hydrogen-induced SCC. In addition, irreversible hydrogen traps caused by high pre-strain can severely aggravate hydrogen-induced SCC, resulting in high SCC vulnerability.

Hemophilic articular cartilage damage presents a significant challenge for surgeons, characterized by recurrent intraarticular bleeding, a severe inflammatory microenvironment, and limited self-repair capability of cartilage tissue. Currently, there is a lack of tissue engineering-based integrated therapies that address both early hemostasis, anti-inflammation, and long-lasting chondrogenesis for hemophilic articular cartilage defects. Herein, we developed an adhesive hydrogel using oxidized chondroitin sulfate and gelatin, loaded with exosomes derived from bone marrow stem cells (BMSCs) (Hydrogel-Exos). This hydrogel demonstrated favorable injectability, self-healing, biocompatibility, biodegradability, swelling, frictional and mechanical properties, providing a comprehensive approach to treating hemophilic articular cartilage defects. The adhesive hydrogel, featuring dynamic Schiff base bonds and hydrogen bonds, exhibited excellent wet tissue adhesiveness and hemostatic properties. In a pig model, the hydrogel could be smoothly injected into the knee joint cartilage defect site and gelled in situ under fluid-irrigated arthroscopic conditions. Our in vitro and in vivo experiments confirmed that the sustained release of exosomes yielded anti-inflammatory effects by modulating macrophage M2 polarization through the NF-κB pathway. This immunoregulatory effect, coupled with the extracellular matrix components provided by the adhesive hydrogel, enhanced chondrogenesis, promoted the cartilage repair and joint function restoration after hemophilic articular cartilage defects. In conclusion, our results highlight the significant application potential of Hydrogel-Exos for early hemostasis, immunoregulation, and long-term chondrogenesis in hemophilic patients with cartilage injuries. This innovative approach is well-suited for application during arthroscopic procedures, offering a promising solution for addressing the complex challenges associated with hemophilic articular cartilage damage.

Mucosal vaccines offer potential benefits over parenteral vaccines for they can trigger both systemic immune protection and immune responses at the predominant sites of pathogen infection. However, the defense function of mucosal barrier remains a challenge for vaccines to overcome. Here, we show that surface modification of exosomes with the fragment crystallizable (Fc) part from IgG can deliver the receptor-binding domain (RBD) of SARS-CoV-2 to cross mucosal epithelial layer and permeate into peripheral lung through neonatal Fc receptor (FcRn) mediated transcytosis. The exosomes F-L-R-Exo are generated by genetically engineered dendritic cells, in which a fusion protein Fc-Lamp2b-RBD is expressed and anchored on the membrane. After intratracheally administration, F-L-R-Exo is able to induce a high level of RBD-specific IgG and IgA antibodies in the animals’ lungs. Furthermore, potent Th1 immune-biased T cell responses were also observed in both systemic and mucosal immune responses. F-L-R-Exo can protect the mice from SARS-CoV-2 pseudovirus infection after a challenge. These findings hold great promise for the development of a novel respiratory mucosal vaccine approach.

Due to overactive inflammation and hindered angiogenesis, self-healing of diabetic wounds (DW) remains challenging in the clinic. Platelet-derived exosomes (PLT-Exos), a novel exosome capable of anti-inflammation and pro-angiogenesis, show great potential in DW treatment. However, previous administration of exosomes into skin wounds is topical daub or intradermal injection, which cannot intradermally deliver PLT-Exos into the dermis layer, thus impeding its long-term efficacy in anti-inflammation and pro-angiogenesis. Herein, a dissolvable microneedle-based wound dressing (PLT-Exos@ADMMA-MN) was developed for transdermal and long-term delivery of PLT-Exos. Firstly, a photo-crosslinking methacrylated acellular dermal matrix-based hydrogel (ADMMA-GEL), showing physiochemical tailorability, fast-gelling performance, excellent biocompatibility, and pro-angiogenic capacities, was synthesized as a base material of our dressing. For endowing the dressing with anti-inflammation and pro-angiogenesis, PLT-Exos were encapsulated into ADMMA-GEL with a minimum effective concentration determined by our in-vitro experiments. Then, in-vitro results show that this dressing exhibits excellent properties in anti-inflammation and pro-angiogenesis. Lastly, in-vivo experiments showed that this dressing could continuously and transdermally deliver PLT-Exos into skin wounds to switch local macrophage into M2 phenotype while stimulating neovascularization, thus proving a low-inflammatory and pro-angiogenic microenvironment for DW healing. Collectively, this study provides a novel wound dressing capable of suppressing inflammation and stimulating vascularization for DW treatment.

Vascular calcification and vascular ageing are “silent” diseases but are highly prevalent in patients with end stage renal failure and type 2 diabetes, as well as in the ageing population. Melatonin (MT) has been shown to induce cardiovascular protection effects. However, the role of MT on vascular calcification and ageing has not been well-identified. In this study, the aortic transcriptional landscape revealed clues for MT related cell-to-cell communication between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) in vascular calcification and vascular ageing. Furthermore, we elucidated that it was exosomes that participate in the information transportation from ECs to VSMCs. The exosomes secreted from melatonin-treated ECs (MT-ECs-Exos) inhibited calcification and senescence of VSMCs. Mechanistically, miR-302d-5p was highly enriched in MT-ECs-Exos, while depletion of miR-302d-5p blocked the ability of MT-ECs-Exos to suppress VSMC calcification and senescence. Notably, Wnt3 was a bona fide target of miR-302d-5p and modulated VSMC calcification and senescence. Furthermore, we found that maturation of endothelial derived exosomal miR-302d-5p was promoted by WTAP in an N6-methyladenosine (m6A)-dependent manner. Interestingly, MT alleviated vascular calcification and ageing in 5/6-nephrectomy (5/6 NTP) mice, a chronic kidney disease (CKD) induced vascular calcification and vascular ageing mouse model. MT-ECs-Exos was absorbed by VSMCs in vivo and effectively prevented vascular calcification and ageing in 5/6 NTP mice. ECs-derived miR-302d-5p mediated MT induced anti-calcification and anti-ageing effects in 5/6 NTP mice. Our study suggests that MT-ECs-Exos alleviate vascular calcification and ageing through the miR-302d-5p/Wnt3 signaling pathway, dependent on m6A methylation.

Biofilm-related biomaterial infections are notoriously challenging to treat and can lead to chronic infection and persisting inflammation. To date, a large body of research can be reviewed for coatings which potentially prevent bacterial infection while promoting implant integration. Yet only a very small number has been translated from bench to bedside. This study provides an in-depth analysis of the stability, antibacterial mechanism, and biocompatibility of medical grade polycaprolactone (mPCL), coated with human serum albumin (HSA), the most abundant protein in blood plasma, and tannic acid (TA), a natural polyphenol with antibacterial properties. Molecular docking studies demonstrated that HSA and TA interact mainly through hydrogen-bonding, ionic and hydrophobic interactions, leading to smooth and regular assemblies. In vitro bacteria adhesion testing showed that coated scaffolds maintained their antimicrobial properties over 3 days by significantly reducing S. aureus colonization and biofilm formation. Notably, amplitude modulation-frequency modulation (AMFM) based viscoelasticity mapping and transmission electron microscopy (TEM) data suggested that HSA/TA-coatings cause morphological and mechanical changes on the outer cell membrane of S. aureus leading to membrane disruption and cell death while proving non-toxic to human primary cells. These results support this antibiotic-free approach as an effective and biocompatible strategy to prevent biofilm-related biomaterial infections.

Most acute ischemic stroke patients with large vessel occlusion require stent implantation for complete recanalization. Yet, due to ischemia-reperfusion injury, over half of these patients still experience poor prognoses. Thus, neuroprotective treatment is imperative to alleviate the ischemic brain injury, and a proof-of-concept study was conducted on “biodegradable neuroprotective stent”. This concept is premised on the hypothesis that locally released Mg2+/H2 from Mg metal within the bloodstream could offer synergistic neuroprotection against reperfusion injury in distant cerebral ischemic tissues. Initially, the study evaluated pure Mg's neuroactive potential using oxygen-glucose deprivation/reoxygenation (OGD/R) injured neuron cells. Subsequently, a pure Mg wire was implanted into the common carotid artery of the transient middle cerebral artery occlusion (MCAO) rat model to simulate human brain ischemia/reperfusion injury. In vitro analyses revealed that pure Mg extract aided mouse hippocampal neuronal cell (HT-22) in defending against OGD/R injury. Additionally, the protective effects of the Mg wire on behavioral abnormalities, neural injury, blood-brain barrier disruption, and cerebral blood flow reduction in MCAO rats were verified. Conclusively, Mg-based biodegradable neuroprotective implants could serve as an effective local Mg2+/H2 delivery system for treating distant cerebral ischemic diseases.

As a powerful paradigm, artificial intelligence (AI) is rapidly impacting every aspect of our day-to-day life and scientific research through interdisciplinary transformations. Living human organoids (LOs) have a great potential for in vitro reshaping many aspects of in vivo true human organs, including organ development, disease occurrence, and drug responses. To date, AI has driven the revolutionary advances of human organoids in life science, precision medicine and pharmaceutical science in an unprecedented way. Herein, we provide a forward-looking review, the frontiers of LOs, covering the engineered construction strategies and multidisciplinary technologies for developing LOs, highlighting the cutting-edge achievements and the prospective applications of AI in LOs, particularly in biological study, disease occurrence, disease diagnosis and prediction and drug screening in preclinical assay. Moreover, we shed light on the new research trends harnessing the power of AI for LO research in the context of multidisciplinary technologies. The aim of this paper is to motivate researchers to explore organ function throughout the human life cycle, narrow the gap between in vitro microphysiological models and the real human body, accurately predict human-related responses to external stimuli (cues and drugs), accelerate the preclinical-to-clinical transformation, and ultimately enhance the health and well-being of patients.

Skin-nerve interaction plays an important role in promoting wound healing. However, in diabetic ulcers (DUs), the diabetic periphery neuropathy and excessive levels of reactive oxygen species (ROS) block skin-nerve interaction and further impede the DUs healing. Herein, we developed a nanoscale metal-organic framework loaded with nerve growth factor (NGF/Ce-UiO-66, denoted NGF/CU) for the treatment of DUs. The Ce-UiO-66 (CU) was applied as an antioxidant to scavenge ROS and reduce the inflammatory response while the NGF aided in the recovery of cutaneous nerves to further promote DUs healing. Both in vitro and in vivo experiments revealed the effective ability of NGF/CU for DUs healing. Subsequent RNA sequencing analysis revealed the mechanism that NGF/CU can improve wound healing by inhibiting the NF-κB signaling pathway and recovering the neuroendocrine system of the skin. This strategy of nerve regulation will provide more ideas for the treatment of DUs and other organ injuries.

Abnormal hyperphosphorylation of tau protein is a principal pathological hallmark in the onset of neurodegenerative disorders, such as Alzheimer's disease (AD), which can be induced by an excess of reactive oxygen species (ROS). As an antioxidant, hydrogen gas (H2) has the potential to mitigate AD by scavenging highly harmful ROS such as •OH. However, conventional administration methods of H2 face significant challenges in controlling H2 release on demand and fail to achieve effective accumulation at lesion sites. Herein, we report artificial nanoreactors that mimic natural photosynthesis to realize near-infrared (NIR) light-driven photocatalytic H2 evolution in situ. The nanoreactors are constructed by biocompatible crosslinked vesicles (CVs) encapsulating ascorbic acid and two photosensitizers, chlorophyll a (Chla) and indoline dye (Ind). In addition, platinum nanoparticles (Pt NPs) serve as photocatalysts and upconversion nanoparticles (UCNP) act as light-harvesting antennas in the nanoreacting system, and both attach to the surface of CVs. Under NIR irradiation, the nanoreactors release H2 in situ to scavenge local excess ROS and attenuate tau hyperphosphorylation in the AD mice model. Such NIR-triggered nanoreactors provide a proof-of-concept design for the great potential of hydrogen therapy against AD.

Demand for biliary stents has expanded with the increasing incidence of biliary disease. The implantation of plastic or self-expandable metal stents can be an effective treatment for biliary strictures. However, these stents are nondegradable and prone to restenosis. Surgical removal or replacement of the nondegradable stents is necessary in cases of disease resolution or restenosis. To overcome these shortcomings, improvements were made to the materials and surfaces used for the stents. First, this paper reviews the advantages and limitations of nondegradable stents. Second, emphasis is placed on biodegradable polymer and biodegradable metal stents, along with functional coatings. This also encompasses tissue engineering & 3D-printed stents were highlighted. Finally, the future perspectives of biliary stents, including pro-epithelialization coatings, multifunctional coated stents, biodegradable shape memory stents, and 4D bioprinting, were discussed.

In vivo implantation of microelectrodes opens the door to studying neural circuits and restoring damaged neural pathways through direct electrical stimulation and recording. Although some neuroprostheses have achieved clinical success, electrode material properties, inflammatory response, and glial scar formation at the electrode-tissue interfaces affect performance and sustainability. Those challenges can be addressed by improving some of the materials' mechanical, physical, chemical, and electrical properties. This paper reviews materials and designs of current microelectrodes and discusses perspectives to advance neuroprosthetics performance.

Effective treatment of infection in chronic wounds is critical to improve patient outcomes and prevent severe complications, including systemic infections, increased morbidity, and amputations. Current treatments, including antibiotic administration and antimicrobial dressings, are challenged by the increasing prevalence of antibiotic resistance and patients’ sensitivity to the delivered agents. Previous studies have demonstrated the potential of a new antimicrobial agent, Gallium maltolate (GaM); however, the high burst release from the GaM-loaded hydrogel gauze required frequent dressing changes. To address this need, we developed a hydrogel foam-based wound dressing with GaM-loaded microspheres for sustained infection control. First, the minimal inhibitory and bactericidal concentrations (MIC and MBC) of GaM against two Staphylococcus aureus strains isolated from chronic wounds were identified. No significant adverse effects of GaM on dermal fibroblasts were shown at the MIC, indicating an acceptable selectivity index. For the sustained release of GaM, electrospraying was employed to fabricate microspheres with different release kinetics. Systematic investigation of loading and microsphere size on release kinetics indicated that the larger microsphere size and lower GaM loading resulted in a sustained GaM release profile over the target 5 days. Evaluation of the GaM-loaded hydrogel dressing demonstrated cytocompatibility and antibacterial activities with a zone of inhibition test. An equine distal limb wound model was developed and utilized to demonstrate the efficacy of GaM-loaded hydrogel foam in vivo. This antimicrobial hydrogel foam dressing displayed the potential to combat methicillin-resistant S. aureus (MRSA) infection with controlled GaM release to improve chronic wound healing.

A common problem for Zn alloys is the trade-off between antibacterial ability and biocompatibility. This paper proposes a strategy to solve this problem by increasing release ratio of Ca2+ ions, which is realized by significant refinement of CaZn13 particles through bottom circulating water-cooled casting (BCWC) and rolling. Compared with conventionally fabricated Zn-0.3Ca alloy, the BCWC-rolled alloy shows higher antibacterial abilities against E. coli and S. aureus, meanwhile much less toxicity to MC3T3-E1 cells. Additionally, plasticity, degradation uniformity, and ability to induce osteogenic differentiation in vitro of the alloy are improved. The elongation up to 49 %, which is the highest among Zn alloys with Ca, and is achieved since the sizes of CaZn13 particles and Zn grains are small and close. As a result, the long-standing problem of low formability of Zn alloys containing Ca has also been solved due to the elimination of large CaZn13 particles. The BCWC-rolled alloy is a promising candidate of making GBR membrane.

Adoptive immunotherapy, notably involving chimeric antigen receptor (CAR)-T cells, has obtained Food and Drug Administration (FDA) approval as a treatment for various hematological malignancies, demonstrating promising preclinical efficacy against cancers. However, the intricate and resource-intensive autologous cell processing, encompassing collection, expansion, engineering, isolation, and administration, hamper the efficacy of this therapeutic modality. Furthermore, conventional CAR T therapy is presently confined to addressing solid tumors due to impediments posed by physical barriers, the potential for cytokine release syndrome, and cellular exhaustion induced by the immunosuppressive and heterogeneous tumor microenvironment. Consequently, a strategic integration of adoptive immunotherapy with synergistic multimodal treatments, such as chemotherapy, radiotherapy, and vaccine therapy etc., emerges as a pivotal approach to surmount these inherent challenges. This collaborative strategy holds the key to addressing the limitations delineated above, thereby facilitating the realization of more precise personalized therapies characterized by heightened therapeutic efficacy. Such synergistic strategy not only serves to mitigate the constraints associated with adoptive immunotherapy but also fosters enhanced clinical applicability, thereby advancing the frontiers of therapeutic precision and effectiveness.

Soft tissue seal around the transmucosal region of dental implants is crucial for shielding oral bacterial invasion and guaranteeing the long-term functioning of implants. Compared with the robust periodontal tissue barrier around a natural tooth, the peri-implant mucosa presents a lower bonding efficiency to the transmucosal region of dental implants, due to physiological structural differences. As such, the weaker soft tissue seal around the transmucosal region can be easily broken by oral pathogens, which may stimulate serious inflammatory responses and lead to the development of peri-implant mucositis. Without timely treatment, the curable peri-implant mucositis would evolve into irreversible peri-implantitis, finally causing the failure of implantation. Herein, this review has summarized current surface modification strategies for the transmucosal region of dental implants with improved soft tissue bonding capacities (e.g., improving surface wettability, fabricating micro/nano topographies, altering the surface chemical composition and constructing bioactive coatings). Furthermore, the surfaces with advanced soft tissue bonding abilities can be incorporated with antibacterial properties to prevent infections, and/or with immunomodulatory designs to facilitate the establishment of soft tissue seal. Finally, we proposed future research orientations for developing multifunctional surfaces, thus establishing a firm soft tissue seal at the transmucosal region and achieving the long-term predictability of dental implants.

Complete wound healing without scar formation has attracted increasing attention, prompting the development of various strategies to address this challenge. In clinical settings, there is a growing preference for emerging biomedical technologies that effectively manage fibrosis following skin injury, as they provide high efficacy, cost-effectiveness, and minimal side effects compared to invasive and costly surgical techniques. This review gives an overview of the latest developments in advanced biomedical technologies for scarless wound management. We first introduce the wound healing process and key mechanisms involved in scar formation. Subsequently, we explore common strategies for wound treatment, including their fabrication methods, superior performance and the latest research developments in this field. We then shift our focus to emerging biomedical technologies for scarless wound healing, detailing the mechanism of action, unique properties, and advanced practical applications of various biomedical technology-based therapies, such as cell therapy, drug therapy, biomaterial therapy, and synergistic therapy. Finally, we critically assess the shortcomings and potential applications of these biomedical technologies and therapeutic methods in the realm of scar treatment.

Biodegradable magnesium implants offer a solution for bone repair without the need for implant removal. However, concerns persist regarding peri-implant gas accumulation, which has limited their widespread clinical acceptance. Consequently, there is a need to minimise the mass of magnesium to reduce the total volume of gas generated around the implants. Incorporating porosity is a direct approach to reducing the mass of the implants, but it also decreases the strength and degradation resistance. This study demonstrates that the infiltration of a calcium phosphate cement into an additively manufactured WE43 Mg alloy scaffold with 75 % porosity, followed by hydrothermal treatment, yields biodegradable magnesium/hydroxyapatite interpenetrating phase composites that generate an order of magnitude less hydrogen gas during degradation than WE43 scaffolds. The enhanced degradation resistance results from magnesium passivation, allowing osteoblast proliferation in indirect contact with composites. Additionally, the composites exhibit a compressive strength 1.8 times greater than that of the scaffolds, falling within the upper range of the compressive strength of cancellous bone. These results emphasise the potential of the new biodegradable interpenetrating phase composites for the fabrication of temporary osteosynthesis devices. Optimizing cement hardening and magnesium passivation during hydrothermal processing is crucial for achieving both high compressive strength and low degradation rate.

Clusterzymes are synthetic enzymes exhibiting substantial catalytic activity and selectivity, which are uniquely driven by single-atom constructs. A dramatic increase in antioxidant capacity, 158 times more than natural trolox, is noted when single-atom copper is incorporated into gold-based clusterzymes to form Au24Cu1. Considering the inflammatory and mildly acidic microenvironment characteristic of osteoarthritis (OA), pH-dependent dendritic mesoporous silica nanoparticles (DMSNs) coupled with PEG have been employed as a delivery system for the spatial-temporal release of clusterzymes within active articular regions, thereby enhancing the duration of effectiveness. Nonetheless, achieving high therapeutic efficacy remains a significant challenge. Herein, we describe the construction of a Clusterzymes-DMSNs-PEG complex (CDP) which remarkably diminishes reactive oxygen species (ROS) and stabilizes the chondroprotective protein YAP by inhibiting the Hippo pathway. In the rabbit ACLT (anterior cruciate ligament transection) model, the CDP complex demonstrated inhibition of matrix metalloproteinase activity, preservation of type II collagen and aggregation protein secretion, thus prolonging the clusterzymes' protective influence on joint cartilage structure. Our research underscores the efficacy of the CDP complex in ROS-scavenging, enabled by the release of clusterzymes in response to an inflammatory and slightly acidic environment, leading to the obstruction of the Hippo pathway and downstream NF-κB signaling pathway. This study illuminates the design, composition, and use of DMSNs and clusterzymes in biomedicine, thus charting a promising course for the development of novel therapeutic strategies in alleviating OA.

Electrospun nanofibrous membranes (eNFMs) have been extensively developed for bio-applications due to their structural and compositional similarity to the natural extracellular matrix. However, the emergence of antibiotic resistance in bacterial infections significantly impedes the further development and applications of eNFMs. The development of antibacterial nanomaterials substantially nourishes the engineering design of antibacterial eNFMs for combating bacterial infections without relying on antibiotics. Herein, a comprehensive review of diverse fabrication techniques for incorporating antibacterial nanomaterials into eNFMs is presented, encompassing an exhaustive introduction to various nanomaterials and their bactericidal mechanisms. Furthermore, the latest achievements and breakthroughs in the application of these antibacterial eNFMs in tissue regenerative therapy, mainly focusing on skin, bone, periodontal and tendon tissues regeneration and repair, are systematically summarized and discussed. In particular, for the treatment of skin infection wounds, we highlight the antibiotic-free antibacterial therapy strategies of antibacterial eNFMs, including (i) single model therapies such as metal ion therapy, chemodynamic therapy, photothermal therapy, and photodynamic therapy; and (ii) multi-model therapies involving arbitrary combinations of these single models. Additionally, the limitations, challenges and future opportunities of antibacterial eNFMs in biomedical applications are also discussed. We anticipate that this comprehensive review will provide novel insights for the design and utilization of antibacterial eNFMs in future research.

Through-thickness corrosion homogeneity of stabilized AA5083 alloy thick plate was investigated. For the as-received stabilized plates, no differences in corrosion behavior are evident in the specimens from different sampling positions along the thickness direction. However, in the plates after sensitization, the specimen from the surface position (T/10, SP) exhibits the highest degree of sensitization (DoS) and stress corrosion cracking (SCC) susceptibility, indicating the through-thickness corrosion inhomogeneity. Compared with interlayer position (3T/10, IP) and center position (T/2, CP), the higher grain stored energy and richer high angle grain boundaries (HAGBs) in SP specimens promote the formation of β phases (Al3Mg2) during the sensitization process. It results in a high coverage of β phases in the SP specimen and therefore induces severe corrosion.

Polybutylene succinate, polybutylene adipate, polybutylene suberate and their copolyesters were synthesized. The physical properties and biodegradability of these polyesters were controlled by adjusting the composition of carboxyl monomers. Compared with the homopolyesters, the addition of comonomer during polymerization resulted in the formation of copolyesters with lower melting temperatures and crystallinity. Among them, poly(butylene succinate-co-adipate) (PBSA) had the lowest crystallinity, and poly(butylene adipate-co-suberate) (PBASub) had the lowest melting point. The elongation at break and tensile strength of PBSA was 766.2% and 21.5 MPa, respectively. Enzymatic degradation by Fusarium solani cutinase (FsC) showed that both the crystalline and amorphous regions of the polyester were simultaneously degraded by FsC, and the crystal structure of the polyester was not disrupted. FsC preferentially got attached to the surface of polyesters, subsequently attacked the center of the films, and the water penetrated the amorphous region, leading to enhanced enzymatic hydrolysis. The biodegradability of copolyester was higher than that of homopolyesters. PBSA and poly(butylene succinate-co-suberate) (PBSSub) were completely degraded in about 10 h, and can be used in agricultural, automotive, electronics, biomedical materials, packaging, etc.

This paper extends previous studies by the authors that aimed to describe the effect of apparent cross-link density (CLD) of the rubber polymer networks on the fracture mechanism caused by cut and chip (CC) wear of natural rubber (NR), demonstrating the positive effect of conventional vulcanization (CV). This work is focused on the determination of the effect of CLD while keeping constant the accelerator-to-sulfur ratio A/S = 0.2, typical for CV systems. For this ratio, different sulfur quantities were chosen, and the concentration of the accelerator N-tert-butyl-benzothiazole sulphonamide (TBBS) was calculated to achieve CLDs in a range from 35 to 524 μmol・cm–3. Standard analyses such as tensile tests, hardness, rebound resilience and DIN abrasion were performed. From these analyses, the optimum physical properties of the NR-based rubber were estimated to be in the CLD range of approximately 60 to 160 μmol・cm–3. A CC wear analysis was performed with an Instrumented cut and chip analyzer (ICCA) and it was found that the highest CC wear resistance of the NR is in the CLD range of 35 to 100 μmol・cm–3. Furthermore, the effect of straininduced crystallization (SIC) of NR on CC wear and its dependence on the CLD region was discussed. For the first time, we determine a CLD range for a CV system in which the material achieves both optimal mechanical properties and CC wear resistance.

Carbon black migration between ground tire rubber (GTR) and rubber matrix is essential in developing high-performance rubber/GTR composites. In this work, carbon black N220 (surface area: 107.1 m2/g, particle size: 20–25 nm) and N660 (surface area: 33.1 m2/g, particle size: 49–60 nm) were used as the reinforcement fillers for styrene-butadiene rubber (SBR) blended with reclaimed GTR. The combined effects of GTR devulcanization level and carbon black grade on the properties of SBR/GTR composites were investigated considering curing characteristics, thermal stability, physico-mechanical properties, dynamic mechanical properties, swelling behavior, and morphology. The results showed that, regardless of GTR devulcanization level and carbon black grade, application of GTR resulted in deterioration of mechanical properties compared to a reference sample without GTR. It was observed the reinforcement effect of carbon black in SBR/GTR composites was more visible with higher devulcanization level of GTR and lower particle sizes of carbon black fillers. SBR/GTR composites reinforced with carbon black N220 were characterized by tensile strength in the range of 15.3–16.3 MPa and abrasion resistance in the range of 120–123 mm3, which justify their potential application in the manufacturing of technical rubber goods or footwear.

Currently, polylactic acid (PLA) is an attractive alternative to polypropylene (PP) because of its biodegradability. This study introduces a novel modification strategy for PLA by creating a multifunctional ionization layer with ionic salts. This approach achieves humidity sensing, reliable antibacterial properties, and excellent degradability simultaneously. The modified PLA textile sensor exhibits high sensitivity to respiratory humidity (0.92 at 90% RH), with ultrafast response (0.12 s) and recovery times (0.16 s). Additionally, the textile demonstrates excellent antibacterial performance against both E. coli (99.9%) and S. aureus (99.9%) after 1 h of contact. It also shows notable biodegradability with a weight loss rate of 60.38% after 30 days. Also, the ionic salt mechanism is explained through dynamic ionization interactions attributed to the modified ionic salts, which feature both long-chain alkanes and active ions. This work presents a new method to enhance the respiratory detection and antibacterial performance of biodegradable masks.

This study aims to develop alkyd-aldehyde and alkyd-ketone blends by modification of waste poly(ethylene terephthalate) (PET) based alkyd resin with urea-aldehyde (UA) and cyclohexanone formaldehyde (CHF) resins for use in coating applications. PET flakes were depolymerized by simultaneous hydrolysis-glycolysis reaction, and depolymerization product (DP) was used completely instead of the diol in the alkyd synthesis. For comparison, reference alkyds without PET were also synthesized. The effect of modifier resin at different ratios and the presence of DP on the coating and thermal properties of blend films were investigated. Medium-hard/hard and gloss/high gloss films with excellent adhesion and impact resistance were obtained from both blends. These films also demonstrated superior chemical and environmental resistance. Blends with CHF resin had better alkali resistance than those with UA resin. In PET-based blends, thermal resistance significantly increased with the addition of the CHF resin to the alkyd resin. Notably, the use of DP did not show a negative effect on the properties of alkyd resin and blend films. On the contrary, much better results were obtained than the alkyd resin alone. Overall, the modification with UA and CHF modifiers and using DP improved the coating properties of the blends. These blends are expected to be considered a sustainable and environmentally friendly alternative for designing versatile coatings for various applications.

This study explores the transformative potential of calcium lignosulfonate (CaL) as a sustainable additive in rubber composites based on nitrile rubber (NBR) and styrene-butadiene rubber (SBR). Through comprehensive mechanical testing, fatigue crack growth (FCG) analysis, and scanning electron microscopy (SEM), we evaluated the tensile strength, elongation at break, surface morphology, and crack growth behavior of these innovative composites. By incorporating CaL into carbon black-reinforced rubber compounds (RUB/CB) based on nitrile rubber and styrene-butadiene rubber, we achieved good dispersion of both components as well as satisfactory morphology, resulting in tensile strengths of 16.3 and 12.7 MPa, respectively. While the CB/CaL hybrid did not significantly influence the intrinsic strength of the rubber samples, the ultimate strength of these compounds increased drastically – over five-fold compared to RUB/CB – indicating great potential for real-life applications. This study underscores the promise of lignin-based additives in the development of eco-friendly, highperformance rubber materials.

Recently, there has been growing interest in materials that combine the advantages of glass and polymer materials. Such a combination results in a kind of hybrid glass-polymer optics that meets the requirements for high-quality imaging in various environmental conditions. So far, the literature on these materials is quite scarce. This article is an attempt to review the most important reports on the topic of available polymers with optical properties, dividing them into groups, i.e. synthetic optical polymers (including polymethylmethacrylate, polyethylene terephthalate, polypropylene, cyclic olefin copolymers and polyolefin elastomers) and biopolymers (including polylactide and gelatin). A separate place and chapter is given to transparent CR-39 plastic and the issue of individual dosimetry for radon detection. Moreover, testing methods for measuring the most important optical properties of polymers and their major applications are briefly discussed.

Phase transition at the initial solidification stage notably affects subsequent phase structure of peritectic alloys, however, detailed dynamics between entangled three-phase region remains ambiguous in the far-from-equilibrium condition during laser additive manufacturing. Here, in-situ peritectic phase transition during single-layer laser printing of an exemplary 304L stainless steel is directly investigated and quantified at high temporospatial resolution by high-speed synchrotron X-ray diffraction and imaging. These quantitative observations clarify the mechanism of coupled peritectic growth and local remelting at three-phase region. The results revealed provide in-depth understanding of phase transformation dynamics and delicate design of phase structure for metal additive manufacturing.

Keeping steps ahead of the bacteria in the race for more efficacious antibacterial strategies is increasingly difficult with the advent of bacterial resistance genes. Herein, we engineered copper sulfide nanoclusters (CuSx NCs) with variable sulfur defects for enhanced dual-treatment of bacterial infections by manipulating photothermal effects and Fenton-like activity. Next, by encasing CuSx NCs with a complex mixture of amino acids and short peptides derived from Luria-Bertani bacterial culture media as a protein corona, we managed to coax E. Coli to take up these CuSx NCs. As a whole, Amino-Pep-CuSx NCs was perceived as a food source and actively consumed by bacteria, enhancing their effective uptake by at least 1.5-fold greater than full length BSA protein BSA-corona CuSx NCs. Through strategically using defect-engineering, we successfully fine-tune photothermal effect and Fenton-like capacity of CuSx NCs. Increased sulfur defects lead to reduced but sufficient heat generation under solar-light irradiation and increased production of toxic hydroxyl radicals. By fine-tuning sulfur defects during synthesis, we achieve CuSx NCs with an optimal synergistic effect, significantly enhancing their bactericidal properties. These ultra-small and biodegradable CuSx NCs can rapidly break down after treatment for clearance. Thus, Amino-Pep-CuSx NCs demonstrate effective eradication of bacteria both in vitro and in vivo because of their relatively high uptake, optimal balanced photothermal and chemodynamic outcomes. Our study offers a straightforward and efficient method to enhance bacterial uptake of next generation of antibacterial agents.

Disperse ferrite is generally embedded in lightweight steel, yet exhibits decent performance, thereby prompting a question: can heterogeneous design optimize it? Here, two representative structures, featured with discontinuous fibrous and dispersed ferrite separately embedded in the austenite matrix, were constructed as examples to address the issue. A heterostructure with fibrous ferrite shows a remarkable product (49 GPa·%) of ultimate strength and total elongation, standing out among other lightweight steels. Superior strength-ductility synergy is primarily attributed to hetero-deformation-induced strengthening and hardening. Abundant hetero-interactions imparted by phase boundaries, dense slip bands in austenite and dislocation networks inside ferrite serve as underlying physical mechanisms.

It remains controversial as to whether a face-centered cubic (FCC) phase exists in pure titanium (Ti) upon deformation, since the FCC structures in deformed Ti may well be TiHx resulting from the sample preparation process. Here, by using in situ transmission electron microscopy (TEM), we uncover direct evidences on the nucleation and growth of FCC-Ti right in front of the crack tip in the α-Ti matrix. Atomic resolution images further reveal that the transformation can be mediated by either partial dislocations on basal planes or shear and atomic shuffle on the FCC1 1 0|HCP1 0 -1 0 interfaces.

This study investigates the plastic deformation-induced fcc → hcp → bcc phase transition within nanograins in an ultra-strong gradient nanostructured surface layer on Fe45Mn35Cr10Co10 compositionally complex alloy (CCA), subjected to a single point cubic boron nitride turning process. High-resolution transmission electron microscope observations reveal a novel atomic movement mechanism of this transition following a unique Nishiyama-Wassermann orientation relationship. Unlike the previously validated Bogers-Burgers-Olson-Cohen model, which follows different orientation relationships and relies on two shear components, this study demonstrates that the phase transition in this CCA is cooperatively completed by two sets of half-partial dislocation dipoles and associated atom shuffling.Statement of NoveltyA novel atomic mechanism of fcc → hcp → bcc phase transition, cooperatively completed by two sets of partial dislocation dipoles and atomic shuffling, provides potential implications for advanced structural materials.

In this study, toughening of WC-Co composite prepared by amorphous-crystallization method was investigated. Co-rich nanoparticles, a Co(W,C) solid solution, were incorporated into the WC matrix through the process integrating crystallization of amorphous Co2W4C powder and its in-situ reaction with carbon. The microstructural evolution of the ceramic-metal composite during fabrication was studied in detail. Owing to the interactions between Co-rich nanoparticles coherent with the WC matrix and the dislocations and stacking faults inside WC grains, the composite exhibited high hardness and strength combined with exceptional fracture toughness. The mechanisms for the synergistic improvement of mechanical properties of the composite were disclosed.

Dislocation evolution in multilayered Ti/Nb composites processed by accumulative roll bonding under uniaxial tension was quantitatively evaluated by high-energy X-ray diffraction. The composites with different heterogeneous microstructures show distinct dislocation activities in Ti, which majorly contributes to their different ductility. For the composite in which extensive shear bands have formed before loading, the stable fraction of 〈c+a〉 dislocations and the suppressed activation of 〈c〉 dislocations contribute to its uniform deformation. We emphasize that tracking the dynamic evolution of dislocations is fundamental for understanding ductility of the multilayers, whereas the increased 〈c+a〉 dislocations found by post-mortem analysis do not necessarily dominate.

Irradiation assisted stress corrosion cracking (IASCC) behavior and irradiated microstructural features of cold-worked 316 stainless steel flux thimble tube specimens were investigated in 340 °C simulated PWR primary water. It covers three dose levels (∼40, ∼60 and ∼100 dpa) and five stress levels (35%, 40%, 50%, 60% and 70% of irradiated yield strength at high temperature. Crack initiation in highly irradiated materials occurred rapidly in 33 failed specimens at high-stress level. A clear dose dependence for IASCC initiation was observed. The susceptibility to IASCC initiation reached saturation around 40–60 dpa. Fracture surface of different dose level O-ring specimens showed that intergranular cracking was the main fracture mode. Discrete slip steps were observed on intergranular fractured regions of each dose level specimens, which is associated as evidence of dislocation channeling. A threshold stress level which was close to 30% yield strength was determined on various testing results from literature and this study. Data scatter was observed for those results from different studies but all agreed on that the failure rate increases with stress level and neutron dose.

Understanding the deformation mechanism in polycrystalline metals is critical to use them in high-value high-risk applications. Here, we report an automated framework based on lattice rotation analysis for accurately identifying slip system and assessing the multiple slip activities in large data set of polycrystalline Zr, aims to statistically provide deep insight on deformation mechanism of Zr. Results show that multiple slip is the dominant slip system rather than single slip system. This method can be applied as a complementary method to the intragranular misorientation axis (IGMA) method and can act as bridges between macro-mechanical response and microstructural deformation mechanisms.

In the present (CoCrNi)92Mo2Al6 medium entropy alloy (MEA), a dual heterogeneous structure is achieved by regulating the degree of recrystallization of the FCC matrix and σ phase precipitation through incomplete annealing. Compared to the alloys with single-phase FCC structure or uniform precipitation structure, this dual heterostructured MEA has superior mechanical properties by possessing the hetero-deformation-induced (HDI) hardening, precipitation strengthening and twinning-induced plasticity (TWIP) mechanism. Our research contributes to the understanding of the micromechanical behavior of heterogeneous materials and also provides a solution to the problem that precipitation increases strength at the expense of plasticity.

Thrombosis and infection are pivotal clinical complications associated with interventional blood-contacting devices, leading to significant morbidity and mortality. To address these issues, we present a stepwise metal-catechol-(amine) (MCA) surface engineering strategy that efficiently integrates therapeutic nitric oxide (NO) gas and antibacterial peptide (ABP) onto catheters, ensuring balanced anti-thrombotic and anti-infective properties. First, copper ions were controllably incorporated with norepinephrine and hexanediamine through a one-step molecular/ion co-assembly process, creating a NO-generating and amine-rich MCA surface coating. Subsequently, azide-polyethylene glycol 4-N-hydroxysuccinimidyl and dibenzylcyclooctyne modified ABP were sequentially immobilized on the surface via amide coupling and bioorthogonal click chemistry, ensuring the dense grafting of ABP while maintaining the catalytic efficacy for NO. This efficient integration of ABP and NO-generating ability on the catheter surface provides potent antibacterial properties and ability to resist adhesion and activation of platelets, thus synergistically preventing infection and thrombosis. We anticipate that this synergistic modification strategy will offer an effective solution for advancing surface engineering and enhancing the clinical performance of biomedical devices.

Thrombosis, a leading cause of cardiovascular morbidity and mortality, involves the formation of blood clots within blood vessels. Current animal models and in vitro systems have limitations in recapitulating the complex human vasculature and hemodynamic conditions, limiting the research in understanding the mechanisms of thrombosis. Bioprinting has emerged as a promising approach to construct biomimetic vascular models that closely mimic the structural and mechanical properties of native blood vessels. This review discusses the key considerations for designing bioprinted vascular conduits for thrombosis studies, including the incorporation of key structural, biochemical and mechanical features, the selection of appropriate biomaterials and cell sources, and the challenges and future directions in the field. The advancements in bioprinting techniques, such as multi-material bioprinting and microfluidic integration, have enabled the development of physiologically relevant models of thrombosis. The future of bioprinted models of thrombosis lies in the integration of patient-specific data, real-time monitoring technologies, and advanced microfluidic platforms, paving the way for personalized medicine and targeted interventions. As the field of bioprinting continues to evolve, these advanced vascular models are expected to play an increasingly important role in unraveling the complexities of thrombosis and improving patient outcomes. The continued advancements in bioprinting technologies and the collaboration between researchers from various disciplines hold great promise for revolutionizing the field of thrombosis research.

Recently, nanovaccine-based immunotherapy has been robustly investigated due to its potential in governing the immune response and generating long-term protective immunity. However, the presentation of a tumor peptide-major histocompatibility complex to T lymphocytes is still a challenge that needs to be addressed for eliciting potent antitumor immunity. Type 1 conventional dendritic cell (cDC1) subset is of particular interest due to its pivotal contribution in the cross-presentation of exogenous antigens to CD8+ T cells. Here, the DC-derived nanovaccine (denoted as Si9GM) selectively targets cDC1s with marginal loss of premature antigen release for effective stimulator of interferon genes (STING)-mediated antigen cross-presentation. Bone marrow dendritic cell (BMDC)-derived membranes, conjugated to cDC1-specific antibody (αCLEC9A) and binding to tumor peptide (OVA257-264), are coated onto dendrimer-like polyethylenimine (PEI)-grafted silica nanoparticles. Distinct molecular weight-cargos (αCLEC9A-OVA257-264 conjugates and 2′3′-cGAMP STING agonists) are loaded in hierarchical center-radial pores that enables lysosome escape for potent antigen-cross presentation and activates interferon type I, respectively. Impressively, Si9GM vaccination leads to the upregulation of cytotoxic T cells, a reduction in tumor regulatory T cells (Tregs), M1/M2 macrophage polarization, and immune response that synergizes with αPD-1 immune checkpoint blockade. This nanovaccine fulfills a dual role for both direct T cell activation as an artificial antigen-presenting cell and DC subset maturation, indicating its utility in clinical therapy and precision medicine.

Heterostructured ferritic steels with bimodal-grained lamellar (BG-L) and ultrafine-grained lamellar (UFG-L) microstructure were prepared through a warm deformation process. The BG-L steel exhibits enhanced mechanical properties compared to conventional quenched and tempered (QT) steel. While the UFG-L steel demonstrates an outstanding combination of strength, ductility, and toughness. Furthermore, the UFG-L steels exhibit no ductile-to-brittle transition (DBT) from room temperature (RT) to liquid nitrogen temperature (LNT) and the Charpy impact energy remains as high as 314 J at LNT. The enhanced toughness at LNT can be attributed to the crack-arrester mechanism caused by grain-boundary delamination.

Deciphering breast cancer treatment resistance remains hindered by the lack of models that can successfully capture the four-dimensional dynamics of the tumor microenvironment. Here, we show that microextrusion bioprinting can reproducibly generate distinct cancer and stromal compartments integrating cells relevant to human pathology. Our findings unveil the functional maturation of this millimeter-sized model, showcasing the development of a hypoxic cancer core and an increased surface proliferation. Maturation was also driven by the presence of cancer-associated fibroblasts (CAF) that induced elevated microvascular-like structures complexity. Such modulation was concomitant to extracellular matrix remodeling, with high levels of collagen and matricellular proteins deposition by CAF, simultaneously increasing tumor stiffness and recapitulating breast cancer fibrotic development. Importantly, our bioprinted model faithfully reproduced response to treatment, further modulated by CAF. Notably, CAF played a protective role for cancer cells against radiotherapy, facilitating increased paracrine communications. This model holds promise as a platform to decipher interactions within the microenvironment and evaluate stroma-targeted drugs in a context relevant to human pathology.

Age-related osteoporosis is a metabolic skeletal disorder caused by estrogen deficiency in postmenopausal women. Prolonged use of anti-osteoporotic drugs such as bisphosphonates and FDA-approved anti-resorptive selective estrogen receptor modulators (SERMs) has been associated with various clinical drawbacks. We recently discovered a low-molecular-weight biocompatible and osteoanabolic phytoprotein, called HKUOT-S2 protein (32 kDa), from Dioscorea opposita Thunb that can accelerate bone defect healing. Here, we demonstrated that the HKUOT-S2 protein treatment can enhance osteoblasts-induced ossification and suppress osteoporosis development by upregulating skeletal estrogen receptors (ERs) ERα, ERβ, and GPR30 expressions in vivo. Also, HKUOT-S2 protein estrogenic activities promoted hMSCs-osteoblasts differentiation and functions by increasing osteogenic markers, ALP, and RUNX2 expressions, ALP activity, and osteoblast biomineralization in vitro. Fulvestrant treatment impaired the HKUOT-S2 protein-induced ERs expressions, osteoblasts differentiation, and functions. Finally, we demonstrated that the HKUOT-S2 protein could bind to ERs to exert osteogenic and osteoanabolic properties. Our results showed that the biocompatible HKUOT-S2 protein can exert estrogenic and osteoanabolic properties by positively modulating skeletal estrogen receptor signaling to promote ossification and suppress osteoporosis. Currently, there is no or limited data if any, on osteoanabolic SERMs. The HKUOT-S2 protein can be applied as a new osteoanabolic SERM for osteoporosis treatment.

Modulating inflammatory cells in an implantation site leads to severe complications and still unsolved challenges for blood-contacting medical devices. Inspired by the role of galectin-1 (Gal-1) in selective functions on multiple cells and immunomodulatory processes, we prepared a biologically target-specific surface coated with the lipid bilayer containing Gal-1 (Gal-1-SLB) and investigate the proof of the biological effects. First, lipoamido-dPEG-acid was deposited on a gold-coated substrate to form a self-assembled monolayer and then conjugated dioleoylphosphatidylethanolamine (DOPE) onto that to produce a lower leaflet of the supported lipid bilayer (SLB) before fusing membrane-derived vesicles extracted from B16-F10 cells. The Gal-1-SLB showed the expected anti-fouling activity by revealing the resistance to protein adsorption and bacterial adhesion. In vitro studies showed that the Gal-1-SLB can promote endothelial function and inhibit smooth muscle cell proliferation. Moreover, Gal-1- SLB presents potential function for endothelial cell migration and angiogenic activities. In vitro macrophage culture studies showed that the Gal-1-SLB attenuated the LPS-induced inflammation and the production of macrophage-secreted inflammatory cytokines. Finally, the implanted Gal-1-SLB reduced the infiltration of immune cells at the tissue-implant interface and increased markers for M2 polarization and blood vessel formation in vivo. This straightforward surface coating with Gal-1 can be a useful strategy for modulating the vascular and immune cells around a blood-contacting device.

Men are particularly sensitive to penis size, especially those with a deformed or injured penis. This can lead to a strong desire for penis enlargement surgery. Given the ethical sensitivities of the penis, penile implants need to be developed with both efficacy and safety. In this study, a polyvinyl alcohol (PVA) patch for penile enlargement prepared via cyclic freeze‒thaw cycles and alkaline treatment. The PVA hydrogels treated with 5 M NaOH had the best mechanical properties and stability. A negative Poisson's ratio structure is incorporated into the design of the enlargement patch, which allows it to conform well to the deformation of the penis. In rabbit models, the enlarged patches can effectively enlarge the penis without degradation or fibrosis while maintaining long-term stability in vivo. This innovation not only provides a safe option for patients in need of penile enlargement but also promises to make a broader contribution to the field of dynamic tissue repair.

Temperature-insensitive elastic modulus known as Elinvar effect is typically achievable in metastable titanium alloys only through thermomechanical processing. Here reports that a directly additively manufactured TiNb-based alloy exhibits Elinvar effect over a wide temperature range of 273 K. This is attributed to its α″+β dual-phase microstructure wherein both the elastic modulus and transition strain of the α″ phase increase monotonically with increasing temperature. The α″ phase was obtained by setting a base-plate temperature of 723 K to act as in-situ aging. This provides a new way to optimize mechanical and functional properties simultaneously by utilizing thermal fields of additive manufacturing.

Hematopoietic stem cell transplantation (HSCT) is extensively employed in the treatment of hematological malignancies but is markedly constrained by the paucity of hematopoietic stem/progenitor cells (HSPCs). Recent studies have found that marrow adipose tissue (MAT) acts on hematopoiesis through complicated mechanisms. Therefore, the osteo-organoids fabricated in vivo using biomaterials loaded with recombinant human bone morphogenetic protein 2 (rhBMP-2) have been used as models of MAT for our research. To obtain sufficient amounts of therapeutic HSPCs and healthy MAT, we have developed amphiphilic chitosan (AC)-gelatin as carriers of rhBMP-2 to the regulate type conversion of adipose tissue and trap hematopoietic growth factors. Unlike medicine interventions or cell therapies, the traps based on AC not only attenuate the occupancy of adipocytes within the hematopoietic microenvironment while preserving stem cell factor concentrations, but also improve marrow metabolism by promoting MAT browning. In conclusion, this approach increases the proportion of HSPCs in osteo-organoids, and optimizes the composition and metabolic status of MAT. These findings furnish an experimental basis for regulating hematopoiesis in vivo through materials that promote the development of autologous HSPCs. Additionally, this approach presents a theoretical model of rapid adipogenesis for the study of adipose-related pathologies and potential pharmacological targets.

The abundance of molecules on early Earth likely enabled a wide range of prebiotic chemistry, with peptides playing a key role in the development of early life forms and the evolution of metabolic pathways. Among peptides, those with enzyme-like activities occupy a unique position between peptides and enzymes, combining both structural flexibility and catalytic functionality. However, their full potential remains largely untapped. Further exploration of these enzyme-like peptides at the nanoscale could provide valuable insights into modern nanotechnology, biomedicine, and even the origins of life. Hence, this review introduces the groundbreaking concept of “peptide nanozymes (PepNzymes)”, which includes single peptides exhibiting enzyme-like activities, peptide-based nanostructures with enzyme-like activities, and peptide-based nanozymes, thus enabling the investigation of biological phenomena at nanoscale dimensions. Through the rational design of enzyme-like peptides or their assembly with nanostructures and nanozymes, researchers have found or created PepNzymes capable of catalyzing a wide range of reactions. By scrutinizing the interactions between the structures and enzyme-like activities of PepNzymes, we have gained valuable insights into the underlying mechanisms governing enzyme-like activities. Generally, PepNzymes play a crucial role in biological processes by facilitating small-scale enzyme-like reactions, speeding up molecular oxidation-reduction, cleavage, and synthesis reactions, leveraging the functional properties of peptides, and creating a stable microenvironment, among other functions. These discoveries make PepNzymes useful for diagnostics, cellular imaging, antimicrobial therapy, tissue engineering, anti-tumor treatments, and more while pointing out opportunities. Overall, this research provides a significant journey of PepNzymes’ potential in various biomedical applications, pushing them towards new advancements.

Bioactive hydrogel materials have great potential for applications in bone tissue engineering. However, fabrication of functional hydrogels that mimic the natural bone extracellular matrix (ECM) remains a challenge, because they need to provide mechanical support and embody physiological cues for angiogenesis and osteogenesis. Inspired by the features of ECM, we constructed a dual-component composite hydrogel comprising interpenetrating polymer networks of gelatin methacryloyl (GelMA) and deoxyribonucleic acid (DNA). Within the composite hydrogel, the GelMA network serves as the backbone for mechanical and biological stability, whereas the DNA network realizes dynamic capabilities (e.g., stress relaxation), thereby promoting cell proliferation and osteogenic differentiation. Furthermore, functional aptamers (Apt19S and AptV) are readily attached to the DNA network to recruit bone marrow mesenchymal stem cells (BMSCs) and achieve sustained release of loaded vascular endothelial growth factor towards angiogenesis. Our results showed that the composite hydrogel could facilitate the adhesion of BMSCs, promote osteogenic differentiation by activating focal adhesion kinase (FAK)/phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)/β-Catenin signaling pathway, and eventually enhance vascularized bone regeneration. This study shows that the multifunctional composite hydrogel of GelMA and DNA can successfully simulate the biological functions of natural bone ECM and has great potential for repairing bone defects.