Smart responsive in situ hydrogel systems applied in bone tissue engineering.

The repair of irregular bone tissue suffers severe clinical problems due to the scarcity of an appropriate therapeutic carrier that can match dynamic and complex bone damage. Fortunately, stimuli-responsive in situ hydrogel systems that are triggered by a special microenvironment could be an ideal method of regenerating bone tissue because of the injectability, in situ gelatin, and spatiotemporally tunable drug release. Herein, we introduce the two main stimulus-response approaches, exogenous and endogenous, to forming in situ hydrogels in bone tissue engineering. First, we summarize specific and distinct responses to an extensive range of external stimuli (e.g., ultraviolet, near-infrared, ultrasound, etc.) to form in situ hydrogels created from biocompatible materials modified by various functional groups or hybrid functional nanoparticles. Furthermore, "smart" hydrogels, which respond to endogenous physiological or environmental stimuli (e.g., temperature, pH, enzyme, etc.), can achieve in situ gelation by one injection in vivo without additional intervention. Moreover, the mild chemistry response-mediated in situ hydrogel systems also offer fascinating prospects in bone tissue engineering, such as a Diels-Alder, Michael addition, thiol-Michael addition, and Schiff reactions, etc. The recent developments and challenges of various smart in situ hydrogels and their application to drug administration and bone tissue engineering are discussed in this review. It is anticipated that advanced strategies and innovative ideas of in situ hydrogels will be exploited in the clinical field and increase the quality of life for patients with bone damage.

Allosteric Activator-Regulated CRISPR/Cas12a System Enables Biosensing and Imaging of Intracellular Endogenous and Exogenous Targets.

Sensors designed based on the trans-cleavage activity of CRISPR/Cas12a systems have opened up a new era in the field of biosensing. The current design of CRISPR/Cas12-based sensors in the "on-off-on" mode mainly focuses on programming the activator strand (AS) to indirectly switch the trans-cleavage activity of Cas12a in response to target information. However, this design usually requires the help of additional auxiliary probes to keep the activator strand in an initially "blocked" state. The length design and dosage of the auxiliary probe need to be strictly optimized to ensure the lowest background and the best signal-to-noise ratio. This will inevitably increase the experiment complexity. To solve this problem, we propose using AS after the "RESET" effect to directly regulate the Cas12a enzymatic activity. Initially, the activator strand was rationally designed to be embedded in a hairpin structure to deprive its ability to activate the CRISPR/Cas12a system. When the target is present, target-mediated strand displacement causes the conformation change in the AS, the hairpin structure is opened, and the CRISPR/Cas12a system is reactivated; the switchable structure of AS can be used to regulate the degree of activation of Cas12a according to the target concentration. Due to the advantages of low background and stability, the CRISPR/Cas12a-based strategy can not only image endogenous biomarkers (miR-21) in living cells but also enable long-term and accurate imaging analysis of the process of exogenous virus invasion of cells. Release and replication of virus genome in host cells are indispensable hallmark events of cell infection by virus; sensitive monitoring of them is of great significance to revealing virus infection mechanism and defending against viral diseases.

A study on the impact of systematic desensitization training on competitive anxiety among Latin dance athletes.

Objective: In the domain of competitive events, Latin dance athletes have always suffered competitive anxiety, which is a prevalent and prevailing psychological facet, in pre-, intra-, and post-competitive engagements. Usually, the implementation of systematic desensitization training is an efficacious approach to reduce competitive anxiety levels in routine sports to fortify psychological resilience of athletes (like swimming, volleyball, and basketball). This study focuses on the effect of systematic desensitization training on competition anxiety in the training of Latin dancers to establish good mental ability and promote the competitive ability of athletes. Methodology: The "Sports Competition Anxiety Test Questionnaire" was used to evaluate and classify the competitive anxiety levels of 150 Latin dance athletes. Then, the top 48 participants were selected (24 in the intervention cohort and 24 in the non-intervention cohort) as the study participants after stratifying anxiety score levels from the highest to the lowest. The intervention group was treated with an 8-week psychological intervention by employing systematic desensitization training techniques (encompassing imagery desensitization and in vivo desensitization). The anxiety levels of the subjects were quantified by employing the "Sport Competition Trait Anxiety Inventory" (CCTAI-C) and the "Competitive State Anxiety Inventory" (CSAI-2) to scrutinize the efficacy of systematic desensitization training in regulating competitive anxiety levels among Latin dance athletes. Results: After applying systematic desensitization training, the intervention group displayed a notable reduction in sport cognitive trait anxiety. Specifically, there was a decrease of 29.37% in social evaluation anxiety, 20.31% in competition preparation anxiety, 16.98% in performance anxiety, 25.16% in failure anxiety, 34.47% in opponent's ability anxiety, and 25.16% in injury anxiety. Moreover, for competitive state anxiety, cognitive state anxiety and somatic state anxiety decreased by 39.19 and 21.43%. The state self-confidence increased by 14.42%. Conclusion: The result indicated that systematic desensitization training not only mitigates anxiety but also positively intervenes in sports-related anxiety. Moreover, systematic desensitization training can significantly diminish competitive anxiety among Latin dance athletes to bolster confidence during competitions. Integrating desensitization training into the regular regimen of Latin dance practice has the potential to fortify dancers' psychological resilience against anxiety.

Photoactivatable CRISPR/Cas12a Sensors for Biomarkers Imaging and Point-of-Care Diagnostics.

In recent years, the CRISPR/Cas12a-based sensing strategy has shown significant potential for specific target detection due to its rapid and sensitive characteristics. However, the "always active" biosensors are often insufficient to manipulate nucleic acid sensing with high spatiotemporal control. It remains crucial to develop nucleic acid sensing devices that can be activated at the desired time and space by a remotely applied stimulus. Here, we integrated photoactivation with the CRISPR/Cas12a system for DNA and RNA detection, aiming to provide high spatiotemporal control for nucleic acid sensing. By rationally designing the target recognition sequence, this photoactivation CRISPR/Cas12a system could recognize HPV16 and survivin, respectively. We combined the lateral flow assay strip test with the CRISPR/Cas12a system to realize the visualization of nucleic acid cleavage signals, displaying potential instant test application capabilities. Additionally, we also successfully realized the temporary control of its fluorescent sensing activity for survivin by photoactivation in vivo, allowing rapid detection of target nucleic acids and avoiding the risk of contamination from premature leaks during storage. Our strategy suggests that the CRISPR/Cas12a platform can be triggered by photoactivation to sense various targets, expanding the technical toolbox for precise biological and medical analysis. This study represents a significant advancement in nucleic acid sensing and has potential applications in disease diagnosis and treatment.

Ultrasound-triggered in situ gelation with ROS-controlled drug release for cartilage repair.

Cartilage defects are usually caused by acute trauma and chronic degeneration. However, it is still a great challenge to improve the repair of articular cartilage defects due to the limited self-regeneration capacity of such defects. Herein, a novel ROS-responsive in situ nanocomposite hydrogel loaded with kartogenin (KGN) and bone marrow-derived stem cells (BMSCs) was designed and constructed via the enzymatic reaction of fibrinogen and thrombin. Meanwhile, a ROS-responsive thioketal (TK)-based liposome was synthesized to load the chondrogenesis-inducing factor KGN, the bioenzyme thrombin and an ultrasound-sensitive agent PpIX. Under ultrasound stimulation, the TK-based liposome was destroyed, followed by in situ gelation of fibrinogen and thrombin. Moreover, sustained release of KGN was realized by regulating the ultrasound conditions. Importantly, ROS generation and KGN release within the microenvironment of the in situ fibrin hydrogel significantly promoted chondrogenic differentiation of BMSCs via the Smad5/mTOR signalling pathway and effectively improved cartilage regeneration in a rat articular cartilage defect model. Overall, the novel in situ nanocomposite hydrogel with ROS-controlled drug release has great potential for efficient cartilage repair.

Second near-infrared photoactivatable nanomedicines for enhanced photothermal-chemodynamic therapy of cancer.

Nanomedicines have been widely used for cancer therapy, while controlling their activity for effective and safe treatment remains a big challenge. Herein, we report the development of a second near-infrared (NIR-II) photoactivatable enzyme-loaded nanomedicine for enhanced cancer therapy. Such a hybrid nanomedicine contains a thermoresponsive liposome shell loaded with copper sulfide nanoparticles (CuS NPs) and glucose oxidase (GOx). The CuS nanoparticles mediate the generation of local heat under 1064 nm laser irradiation, which not only can be used for NIR-II photothermal therapy (PTT), but also leads to the destruction of the thermal-responsive liposome shell to achieve the on-demand release of CuS nanoparticles and GOx. In a tumor microenvironment, GOx oxidizes glucose to produce hydrogen peroxide (H2O2) that acts as a medium to promote the efficacy of chemodynamic therapy (CDT) by CuS nanoparticles. This hybrid nanomedicine enables the synergetic action of NIR-II PTT and CDT to obviously improve efficacy without remarkable side effects via NIR-II photoactivatable release of therapeutic agents. Such a hybrid nanomedicine-mediated treatment can achieve complete ablation of tumors in mouse models. This study provides a promising nanomedicine with photoactivatable activity for effective and safe cancer therapy.

Bone/cartilage targeted hydrogel: Strategies and applications.

The skeletal system is responsible for weight-bearing, organ protection, and movement. Bone diseases caused by trauma, infection, and aging can seriously affect a patient's quality of life. Bone targeted biomaterials are suitable for the treatment of bone diseases. Biomaterials with bone-targeted properties can improve drug utilization and reduce side effects. A large number of bone-targeted micro-nano materials have been developed. However, only a few studies addressed bone-targeted hydrogel. The large size of hydrogel makes it difficult to achieve systematic targeting. However, local targeted hydrogel still has significant prospects. Molecules in bone/cartilage extracellular matrix and bone cells provide binding sites for bone-targeted hydrogel. Drug delivery systems featuring microgels with targeting properties is a key construction strategy for bone-targeted hydrogel. Besides, injectable hydrogel drug depot carrying bone-targeted drugs is another strategy. In this review, we summarize the bone-targeted hydrogel through application environment, construction strategies and disease applications. We hope this article will provide a reference for the development of bone-targeted hydrogels. We also hope this article could increase awareness of bone-targeted materials.

Silk fibroin-based biomaterials for cartilage/osteochondral repair.

Osteoarthritis (OA) is a common joint disease with a high disability rate. In addition, OA not only causes great physiological and psychological harm to patients, but also puts great pressure on the social healthcare system. Pathologically, the disintegration of cartilage and the lesions of subchondral bone are related to OA. Currently, tissue engineering, which is expected to overcome the defects of existing treatment methods, had a lot of research in the field of cartilage/osteochondral repair. Silk fibroin (SF), as a natural macromolecular material with good biocompatibility, unique mechanical properties, excellent processability and degradability, holds great potential in the field of tissue engineering. Nowadays, SF had been prepared into various materials to adapt to the demands of cartilage/osteochondral repair. SF-based biomaterials can also be functionally modified to enhance repair performance further. In this review, the preparation methods, types, structures, mechanical properties, and functional modifications of SF-based biomaterials used for cartilage/osteochondral repair are summarized and discussed. We hope that this review will provide a reference for the design and development of SF-based biomaterials in cartilage/osteochondral repair field.

Tumor redox microenvironment modulating composite hydrogels for enhanced sonodynamic therapy of colorectal cancer.

Effective treatment of colorectal cancer is important to improve the quality of life for patients, which however remains a great challenge in the clinic. Herein, we report the construction of a composite hydrogel that can modulate the tumor redox microenvironment for enhanced sonodynamic therapy (SDT) of colorectal cancer. Such composite hydrogels consist of sonosensitizer protoporphyrin IX (PpIX)-conjugated manganese oxide (MnO2) nanoparticles and a glutathione (GSH) inhibitor after Ca2+ induced in situ gelation in the tumor site. In the acidic tumor microenvironment, MnO2 nanoparticles can produce oxygen to relieve hypoxia and thus amplify the generation of reactive oxygen species (ROS) via the SDT effect. Meanwhile, the GSH inhibitor blocks the intracellular synthesis of GSH, thus leading to further enhanced SDT action. As such, composite hydrogel-mediated enhanced SDT can obviously inhibit the growth of subcutaneous colorectal cancer in mouse models. This study thus offers a tumor microenvironment modulating platform for enhanced therapy of colorectal cancer.

Computational Study on Surface Bonding Based on Nanocone Arrays.

Surface bonding is an essential step in device manufacturing and assembly, providing mechanical support, heat transfer, and electrical integration. Molecular dynamics simulations of surface bonding and debonding failure of copper nanocones are conducted to investigate the underlying adhesive mechanism of nanocones and the effects of separation distance, contact length, temperature, and size of the cones. It is found that van der Waals interactions and surface atom diffusion simultaneously contribute to bonding strength, and different adhesive mechanisms play a main role in different regimes. The results reveal that increasing contact length and decreasing separation distance can simultaneously contribute to increasing bonding strength. Furthermore, our simulations indicate that a higher temperature promotes diffusion across the interface so that subsequent cooling results in better adhesion when compared with cold bonding at the same lower temperature. It also reveals that maximum bonding strength was obtained when the cone angle was around 53°. These findings are useful in designing advanced metallic bonding processes at low temperatures and pressure with tenable performance.

Decreased CDKL2 Expression in Clear Cell Renal Cell Carcinoma Predicts Worse Overall Survival.

Background: Clear cell renal cell carcinoma (ccRCC) is the most frequent and lethal type of kidney cancer. Although differential expression of cyclin-dependent kinase-like 2 (CDKL2) has been reported to be associated with tumor progression in other cancers, its prognostic value, and potential mechanism in patients with ccRCC still remain unknown. Methods: Gene expression analysis was conducted using The Cancer Genome Atlas (TCGA), Gene Expression Omnibus, and International Cancer Genome Consortium databases. Further, clinicopathologic analysis; Kaplan-Meier survival analysis; weighted gene co-expression network analysis; gene set enrichment analysis; gene ontology enrichment; methylation; and immune infiltration analyses were performed using TCGA-kidney renal clear cell carcinoma profiles. CDKL2 translational levels were analyzed using The Human Protein Atlas database. Results: CDKL2 expression was decreased in ccRCC samples retrieved from the four databases. Gender, survival status, histologic grade, clinical stage, TNM classification, and tumor status were closely related to CDKL2 expression. In addition, CDKL2 downregulation was an independent prognostic factor for poor prognosis in multivariate analysis. Enrichment analyses using multiple tests revealed that CDKL2 is not just closely related to immune response but this association is highly correlated as well. Further, we found that CDKL2 expression was significantly correlated with the infiltration levels of T cell CD4 memory resting; monocytes; macrophages M0, M1, and M2; dendritic cells resting; mast cells resting; plasma cells; T cell CD8; and T cell regulatory. Conclusion: This is the first report to study the expression of CDKL2 in ccRCC, wherein we suggest that decreased CDKL2 expression is closely correlated with poor prognosis in ccRCC. We consider that CDKL2 is a novel and potential prognostic biomarker associated with immune infiltrates in ccRCC.

[Relationship between germ cells apoptosis and alterations of total antioxidant capacity, nitric oxide level and nitric oxide synthase activity in testes of rats submitted to alcohol drinking].

OBJECTIVE: To investigate the relationship between germ cells apoptosis and alterations of total antioxidant capacity (T-AOC), nitric oxide(NO) level and nitric oxide synthase (NOS) activity in the testes of rats submitted to alcohol drinking. METHODS: Twenty healthy male Sprague-Dawley rats (3 months old) were randomly divided into two groups: control group and experimental group. 50% alcohol and distilled water were administered intragastrically at a dose of 10 ml/kg body weight to two groups of rats respectively. After twenty-six days, the biochemical parameters (T-AOC, NO level and NOS activity) were measured with spectrophotometric determination. The TdT-mediated dUTP-X nick end labeling (TUNEL) technique was used to detect germ cells apoptotic index (AI). RESULTS: Compared with the control group, AI was significantly higher (P < 0.01) in the experimental group; T-AOC level reduced obviously (P < 0.01), but NO level and NOS activity increased predominantly ( P < 0.01). CONCLUSION: The excessive production of NO caused by the increasing of NOS activity and the decreasing of T-AOC may be the main causes that alcohol overtaking induces germ cells apoptosis.