Visible-light-initiated external photocatalyst-free synthesis of α,α-difluoro-ß-ketoamides from 4-aminocoumarins.

A concise and efficient ring-opening difluorination strategy was developed for the synthesis of highly functionalized hydroxy-containing α,α-difluoro-ß-ketoamides from the one-pot multicomponent reaction of 4-aminocoumarins, NFSI, and water in dimethyl carbonate (DMC) as a green solvent. The reactions were smoothly achieved under visible light irradiation in air at room temperature without the addition of any other external photocatalysts. With this protocol, various α,α-difluoro-ß-ketoamides were successfully synthesized under mild conditions (25 examples, 73-91% yields). This transition-metal-free synthetic procedure shows good functional group compatibility and attractive practical potential for large-scale synthesis.

Substrate-Controlled Regioselectivity Switchable [3 + 2] Annulations To Access Spirooxindole Skeletons.

The additive-free [3 + 2] annulation from isatins, amino acids with 2-styrylbenzoxazoles, was described, providing a series of functional and structurally complex 3,3'-pyrrolidinyl-spirooxindole derivatives containing four contiguous and two quaternary stereogenic centers in high yields (up to 95%) and excellent diastereoselectivities (up to >25:1 dr). Interestingly, the reaction exhibits switchable regioselectivity depending on the substrate of amino acids. With proline or thioproline as the substrate, the reaction afforded α-regioselective spirooxindole skeletons. In contrast, when piperidine acid is the substrate, the reaction provided γ-regioselective spirooxindole skeletons.

Autism spectrum disorder in a boy with congenital insensitivity to pain with anhidrosis: a case report.

BACKGROUND: In this case report, we described the past history, clinical manifestations, genetic characteristics and cognitive evaluation of a boy with congenital insensitivity to pain with anhidrosis (CIPA) who developed autism spectrum disorder (ASD). CASE PRESENTATION: The boy had an early onset of CIPA at the age of 48 months, and was later diagnosed with ASD at 5 years old. Developmental delays in communication, social skills and the presence of maladaptive behaviors were observed in the patient. Professional treatments significantly improved the developmental delays. CONCLUSIONS: This case demonstrated that ASD may develop in children with CIPA, and pediatricians should be aware that if they suspect or identify a child with CIPA that they should also be screened for ASD using similar examination and diagnostic tools as shown in the present report. Moreover, therapeutic interventions for ASD was helpful for the remission of both diseases.

Nitrogen-doped carbon dots as a fluorescent probe for the highly sensitive detection of bilirubin and cell imaging.

Nitrogen-doped carbon dots (NCDs) with bright blue fluorescence were constructed by a hydrothermal method using sucrose and l-proline as raw materials. The NCDs were characterized by transmitted electron microscopy, X-ray diffraction, Fourier-transform infrared spectrometry, X-ray photoelectron spectroscopy, and ultraviolet-visible absorption and fluorescence spectroscopy to investigate the morphology, elemental composition, and optical properties. The NCDs had good water solubility, high dispersibility with an average diameter of only 1.7 nm, and satisfactory optical properties with a fluorescence quantum yield of 23.4%. The NCDs were employed for the detection of bilirubin. A good linear response of the NCDs in the range 0.35-9.78 µM was obtained for bilirubin with a detection limit of 33 nM. The NCDs were also applied to the analysis of real samples, serum and urine, with a recovery of 95.34% to 104.66%. The low cytotoxicity and good biocompatibility of the NCDs were indicated by an MTT assay and cell imaging of HeLa cells. Compared with other detection systems, using NCDs for bilirubin detection was a facile and efficient method with good selectivity and sensitivity.

Novel SCN9A missense mutations contribute to congenital insensitivity to pain: Unexpected correlation between electrophysiological characterization and clinical phenotype.

Congenital insensitivity to pain (OMIM 243000) is an extremely rare disorder caused by loss-of-function mutations in SCN9A encoding Nav1.7. Although the SCN9A mutations and phenotypes of painlessness and anosmia/hyposmia in patients are previously well documented, the complex relationship between genotype and phenotype of congenital insensitivity to pain remains unclear. Here, we report a congenital insensitivity to pain patient with novel SCN9A mutations. Functional significance of novel SCN9A mutations was assessed in HEK293 cells expressing Nav1.7, the results showed that p.Arg99His significantly decreased current density and reduced total Nav1.7 protein levels, whereas p.Trp917Gly almost abolished Nav1.7 sodium current without affecting its protein expression. These revealed that mutations in Nav1.7 in this congenital insensitivity to pain patient still retained partial channel function, but the patient showed completely painlessness, the unexpected genotypic-phenotypic relationship of SCN9A mutations in our patient may challenge the previous findings "Nav1.7 total loss-of-function leads to painlessness." Additionally, these findings are helpful for understanding the critical amino acid for maintaining function of Nav1.7, thus contributing to the development of Nav1.7-targeted analgesics.

Ultrasensitive and Selective Determination of Carcinoembryonic Antigen Using Multifunctional Ultrathin Amino-Functionalized Ti3C2-MXene Nanosheets.

Herein, we report on a two-dimensional amino-functionalized Ti3C2-MXene (N-Ti3C2-MXene)-based surface plasmon resonance (SPR) biosensor for detecting carcinoembryonic antigen (CEA) utilizing a sandwich format signal amplification strategy. Our biosensor employs an N-Ti3C2-MXene nanosheet-modified sensing platform and a signal enhancer comprising N-Ti3C2-MXene-hollow gold nanoparticles (HGNPs)-staphylococcal protein A (SPA) complexes. Ultrathin Ti3C2-MXene nanosheets were synthesized and functionalized with aminosilane to provide a hydrophilic-biocompatible nanoplatform for covalent immobilization of the monoclonal anti-CEA capture antibody (Ab1). The N-Ti3C2-MXene/HGNPs nanohybrids were synthesized and further decorated with SPA to immobilize the polyclonal anti-CEA detection antibody (Ab2) and serve as signal enhancers. The capture of CEA followed by the formation of the Ab2-conjugated SPA/HGNPs/N-Ti3C2-MXene sandwiched nanocomplex on the SPR chip results in the generation of a response signal. The fabricated N-Ti3C2-MXene-based SPR biosensor exhibited a linear detection range of 0.001-1000 PM with a detection limit of 0.15 fM. The proposed biosensor showed high sensitivity and specificity for CEA in serum samples, which gives it application potential in the early diagnosis and monitoring of cancer. We believe that this work also opens new avenues for development of MXene-based highly sensitive biosensors for determining various biomolecules.

miR-214-5p targets KLF5 and suppresses proliferation of human hepatocellular carcinoma cells.

MicroRNAs (miRNAs) are small endogenous conserved RNAs regulating genes expression through base pairing with the 3'-untranslated region (3'-UTR) of target messenger RNAs. MiR-214-5p is a newly identified miRNA with its biological role largely unknown. In this study, we explored miR-214-5p expression status in 78 paired tumor and nontumor tissues obtained from patients with hepatocellular carcinoma (HCC) by RT-qPCR. The effects of miR-214-5p expression on HCC cell proliferation, cell cycle progression, and cell migration were measured by CCK-8 assay, flow cytometry, and wound-healing assay. A dual-luciferase activity assay was performed to identify whether KLF5 was a target of miR-214-5p. Kaplan-Meier curve and log-rank test were used to investigate the effects of miR-214-5p and KLF5 on overall survival and disease-free survival of patients with HCC. We found miR-214-5p expression was sharply reduced in HCC tissues and cell lines compared with the normal tissues and cell lines. Functional assay revealed that miR-214-5p overexpression could downregulate cell proliferation, cell migration, and arrested cell cycle at G0/G1 phase. Further, we validated Krüppel-like factor 5 (KLF5) as a direct target of miR-214-5p, and was upregulated in HCC and inversely correlated with the expression of miR-214-5p. Moreover, we found the low expression of miR-214-5p and high expression of KLF5 were correlated with tumor size, tumor stage, and poorer 5-year overall survival and disease-free survival of patients with HCC. In conclusion, our results suggested miR-214-5p functions as a tumor suppressor through targeting KLF5 in HCC. Also, miR-214-5p and KLF5 were identified as potential prognostic markers and might be therapeutic targets in HCC.

A Low-Cost Underground Garage Navigation Switching Algorithm Based on Kalman Filtering.

Modern parking lots have gradually developed into underground garages to improve the efficient use of space. However, the complex design of parking lots also increases the demands on vehicle navigation. The traditional method of navigation switching only uses satellite signals. After the Position Dilution Of Precision (PDOP) of satellite signals is over the limit, vehicle navigation will enter indoor mode. It is not suitable for vehicles in underground garages to switch modes with a fast-response system. Therefore, this paper chooses satellite navigation, inertial navigation, and the car system to combine navigation. With the condition that the vehicle can freely travel through indoor and outdoor environments, high-precision outdoor environment navigation is used to provide the initial state of underground navigation. The position of the vehicle underground is calculated by the Dead Reckoning (DR) navigation system. This paper takes advantage of the Extended Kalman Filter (EKF) algorithm to provide two freely switchable navigation modes for vehicles in ground and underground garages. The continuity, robustness, fast response, and low cost of the indoor and outdoor switching navigation methods are verified in real-time systems.

GAM-Based Mooring Alignment for SINS Based on An Improved CEEMD Denoising Method.

To solve the self-alignment problem of the Strapdown Inertial Navigation System (SINS), a novel adaptive filter based on Complementary Ensemble Empirical Mode Decomposition (CEEMD) is proposed. The Gravitational Apparent Motion (GAM) is used in the coarse alignment, and the problem of obtaining the attitude matrix between the body frame and the navigation frame is attributed to obtaining the matrix between the initial body frame and the current navigation frame using two gravitational apparent motion vectors at different moments. However, the accuracy and time of this alignment method always suffer from the measurement noise of sensors. Thus, a novel adaptive filter based on CEEMD using an l 2 -norm to calculate the similarity measure between the Probability Density Function (PDF) of each Intrinsic Mode Function (IMF) and the original signal is proposed to denoise the measurements of the accelerometer. Furthermore, the advantage of this filter is verified by comparing with other conventional denoising methods, such as PDF-based EMD (EMD-PDF) and the Finite Impulse Response (FIR) digital low-pass filter method. The results of the simulation and experiments indicate that the proposed method performs better than the conventional methods in both alignment time and alignment accuracy.

Increased Nav1.7 expression in the dorsal root ganglion contributes to pain hypersensitivity after plantar incision in rats.

Postoperative pain remains a complex problem that is difficult to manage in the clinical context, seriously affecting rehabilitation and the quality of life of patients after surgery. Nociceptors, of which the cell bodies are located in the dorsal root ganglion, are crucial for initiating and conducting the pain signal. The peripheral voltage-gated sodium channels, including Nav1.7, which is mainly expressed in the dorsal root ganglion, are key to understanding the mechanism underlying postoperative pain. Nav1.7, in particular, of which mutations in the encoding gene ( SCN9A) can determine whether pain occurs, has aroused most attention. Previous studies have shown that Nav1.7 in dorsal root ganglion is critical for the development of inflammatory pain and some neuropathic pain. However, the expression of Nav1.7 in the dorsal root ganglion after surgery and its role in postoperative pain hypersensitivity remain unclear. Therefore, in this study, in order to gain a better understanding of the role of dorsal root ganglion Nav1.7 in pain hypersensitivity following operation, we dynamically examined the pain-related behavior and expression of Nav1.7 in L4-L6 dorsal root ganglion before and after plantar incision in rats (an acute postoperative pain model). After plantar incision, the mechanical and thermal pain threshold decreased significantly, the cumulative pain score was increased significantly, meanwhile quantitative polymerase chain reaction and Western blotting results showed that expression of Nav1.7 in L4-L6 dorsal root ganglion was enhanced significantly. After pretreatment using SCN9A-RNAi-LV delivered via an intrathecal tube, immunohistochemistry showed that increased expression of Nav1.7 in L4-L6 dorsal root ganglion after plantar incision was inhibited, as also confirmed by quantitative polymerase chain reaction and Western blotting. Moreover, pain hypersensitivity was alleviated. These results suggested that Nav1.7 of L4-L6 dorsal root ganglion plays an important role in the development of pain hypersensitivity after plantar incision.

A variant in the SCN10A enhancer may affect human mechanical pain sensitivity.

Expression of Nav1.8, encoded by SCN10A, can affect pain transmission and thus mediate the human pain phenotype. In the current study, we assessed whether the variant rs6801957, located in the SCN10A enhancer region, may have the potential to affect human pain. Through dual-luciferase reporter assays in 293T cells, we found that the SCN10A enhancer A (Enh-A) increased the activity of the SCN10A promoter ( P < 0.05). Additionally, in a cohort of 309 healthy women, mutant rs6801957 A/A was found to have a significant association with decreased human experimental mechanical pain sensitivity ( P < 0.05). We then found that mutant genotype A/A suppressed the increased effect of Enh-A compared with wild-type G/G ( P < 0.05). The association between rs6801957 and human experimental mechanical pain sensitivity was further validated in a larger cohort of 1005 women ( P < 0.05). In conclusion, these results demonstrated that the variant rs6801957 and Enh-A may affect SCN10A gene expression and play an important role in human mechanical pain sensitivity.

Preparation of well-distributed titania nanopillar arrays on Ti6Al4V surface by induction heating for enhancing osteogenic differentiation of stem cells.

Great effort has recently been devoted to the preparation of nanoscale surfaces on titanium-based implants to achieve clinically fast osteoinduction and osseointegration, which relies on the unique characteristics of the nanostructure. In this work, we used induction heating treatment (IHT) as a rapid oxidation method to fabricate a porous nanoscale oxide layer on the Ti6Al4V surface for better medical application. Well-distributed vertical nanopillars were yielded by IHT for 20-35 s on the alloy surface. The composition of the oxides contained rutile/anatase TiO2 and a small amount of Al2O3 between the TiO2 grain boundaries (GBs). This technology resulted in a reduction and subsequent increase of surface roughness of 26-32 nm when upregulating the heating time, followed by the successive enhancement of the thickness, wettability and adhesion strength of the oxidation layer to the matrix. The surface hardness also distinctly rose to 554 HV in the IHT-35 s group compared with the 350 HV of bare Ti6Al4V. The massive small-angle GBs in the bare alloy promoted the formation of nanosized oxide crystallites. The grain refinement and deformation texture reduction further improved the mechanical properties of the matrix after IHT. Moreover, in vitro experiments on a mesenchymal stem cell (BMSC) culture derived from human bone marrow for 1-7 days indicated that the nanoscale layers did not cause cytotoxicity, and facilitated cell differentiation in osteoblasts by enhancing the gene and osteogenesis-related protein expressions after 1-3 weeks of culturing. The increase of the IHT time slightly advanced the BMSC proliferation and differentiation, especially during long-term culture. Our findings provide strong evidence that IHT oxidation technology is a novel nanosurface modification technology, which is potentially promising for further clinical development.

Large valley polarization in monolayer MoTe2 on a magnetic substrate.

On the basis of valley degree of freedom, there would be immense potential application in valleytronics. Introducing magnetism into triangular or hexagonal lattices is a promising route to realize valley polarization, which is indispensable for applying the valley degree of freedom. In this study, we explored valley polarization by depositing a heterostructure of a MoTe2 monolayer on the (0 0 1) surface of an antiferromagnetic RbMnCl3 substrate. First principles-calculations showed that due to proximity-induced Zeeman effects, the MoTe2 monolayer was drastically magnetized by the topmost Mn layer in the substrate and a very large valley splitting (about 109 meV) was achieved. Using an effective Hamiltonian model, the effect of the competition of the spin-orbit coupling (SOC) and exchange field in the system on the valley polarization was also investigated. The magnitude of the valley splitting was found to be limited by the smaller SOC value and the induced exchange field, providing information on the enhancement of the valley polarization. A device rudiment with an anomalous valley Hall effect is proposed.

A SCN10A SNP biases human pain sensitivity.

BACKGROUND: Nav1.8 sodium channels, encoded by SCN10A, are preferentially expressed in nociceptive neurons and play an important role in human pain. Although rare gain-of-function variants in SCN10A have been identified in individuals with painful peripheral neuropathies, whether more common variants in SCN10A can have an effect at the channel level and at the dorsal root ganglion, neuronal level leading to a pain disorder or an altered normal pain threshold has not been determined. RESULTS: Candidate single nucleotide polymorphism association approach together with experimental pain testing in human subjects was used to explore possible common SCN10A missense variants that might affect human pain sensitivity. We demonstrated an association between rs6795970 (G > A; p.Ala1073Val) and higher thresholds for mechanical pain in a discovery cohort (496 subjects) and confirmed it in a larger replication cohort (1005 female subjects). Functional assessments showed that although the minor allele shifts channel activation by -4.3 mV, a proexcitatory attribute, it accelerates inactivation, an antiexcitatory attribute, with the net effect being reduced repetitive firing of dorsal root ganglion neurons, consistent with lower mechanical pain sensitivity. CONCLUSIONS: At the association and mechanistic levels, the SCN10A single nucleotide polymorphism rs6795970 biases human pain sensitivity.

FXR blocks the growth of liver cancer cells through inhibiting mTOR-s6K pathway.

The nuclear receptor Farnesoid X Receptor (FXR) is likely a tumor suppressor in liver tissue but its molecular mechanism of suppression is not well understood. In this study, the gene expression profile of human liver cancer cells was investigated by microarray. Bioinformatics analysis of these data revealed that FXR might regulate the mTOR/S6K signaling pathway. This was confirmed by altering the expression level of FXR in liver cancer cells. Overexpression of FXR prevented the growth of cells and induced cell cycle arrest, which was enhanced by the mTOR/S6K inhibitor rapamycin. FXR upregulation also intensified the inhibition of cell growth by rapamycin. Downregulation of FXR produced the opposite effect. Finally, we found that ectopic expression of FXR in SK-Hep-1 xenografts inhibits tumor growth and reduces expression of the phosphorylated protein S6K. Taken together, our data provide the first evidence that FXR suppresses proliferation of human liver cancer cells via the inhibition of the mTOR/S6K signaling pathway. FXR expression can be used as a biomarker of personalized mTOR inhibitor treatment assessment for liver cancer patients.

A Liquid Metal-Based Temperature-Responsive Low-Toxic Smart Coating for Anti-Biofouling Applications in Marine Engineering.

Titanium alloys have been widely used in marine engineering fields. However, because of high biocompatibility, they are vulnerable to biofouling. In this work, based on the micro-arc oxidation technology and spontaneous galvanic replacement reaction, a temperature-responsive low-toxic smart coating consisting of liquid metal particles is designed to control the release of Ga3+, Cu2+, and Cu1+ ions in different temperatures. This technology can ensure the full release of active ingredients within the target temperature range, intelligently maintaining the excellent anti-biofouling performance, while saving active ingredients. After being immersed in culture media with Sulfate-Reducing Bacteria (SRB) for 14 days at 10, 20, and 30 °C, at the optimal activity temperature of 30 °C for SRB, the best sample releases the highest amounts of Ga3+, Cu2+, and Cu1+ ions, demonstrating a 99.9% bactericidal rate. When the temperature decreases to 10 °C, the activity level of SRB is very low, and the smart coating can also reduce the released ions correspondingly, still with a 97.3% bactericidal rate. The remarkable anti-biofouling performance is attributed to the physical damage and lethal ions interaction. Furthermore, the best sample exhibits good corrosion resistance. This work presents a design route for smart anti-biofouling coatings for temperature-responsive.

Scavenging and release of REE and HFSE by Na-metasomatism in magmatic-hydrothermal systems.

Exploitable or potentially exploitable deposits of critical metals, such as rare-earth (REE) and high-field-strength elements (HFSE), are commonly associated with alkaline or peralkaline igneous rocks. However, the origin, transport and concentration of these metals in peralkaline systems remains poorly understood. This study presents the results of a mineralogical and geochemical investigation of the Na-metasomatism of alkali amphiboles and clinopyroxenes from a barren peralkaline granite pluton in NE China, to assess the remobilization and redistribution of REE and HFSE during magmatic-hydrothermal evolution. Alkali amphiboles and aegirine-augites from the peralkaline granites show evolutionary trends from sodic-calcic to sodic compositions, with increasing REE and HFSE concentrations as a function of increasing Na-index [Na#, defined as molar Na/(Na+Ca) ratios]. The Na-amphiboles (i.e., arfvedsonite) and aegirine-augites can be subsequently altered, or breakdown, to form hydrothermal aegirine during late- or post-magmatic alteration. Representative compositions analyzed by in-situ LA-ICPMS show that the primary aegirine-augites have high and variable REE (2194-3627 ppm) and HFSE (4194-16,862 ppm) contents, suggesting that these critical metals can be scavenged by alkali amphiboles and aegirine-augites. Compared to the primary aegirine-augites, the presentative early replacement aegirine (Aeg-I, Na# = 0.91-0.94) has notably lower REE (1484-1972) and HFSE (4351-5621) contents. In contrast, the late hydrothermal aegirine (Aeg-II, Na# = 0.92-0.96) has significantly lower REE (317-456 ppm) and HFSE (6.44-72.2 ppm) contents. Given that the increasing Na# from aegirine-augites to hydrothermal aegirines likely resulted from Na-metasomatism, a scavenging-release model can explain the remobilization of REE and HFSE in peralkaline granitic systems. The scavenging and release of REE and HFSE by Na-metasomatism provides key insights into the genesis of globally significant REE and HFSE deposits. The high Na-index of the hydrothermal aegirine might be useful as a geochemical indicator in the exploration for these critical-metals.

Efficacy and safety of patient-controlled intravenous analgesia after APS team standardized postoperative pain management: A 6-year experience of an acute pain service in 107802 Chinese patients.

There are few studies on the impact of postoperative pain management (such as Acute Pain Service, APS) on the prognosis of patients, especially the research on large samples, even less data on Chinese patients. It is reported that only 25.12 % of hospitals in China have established APS or similar teams, and less than 10 % of them are responsible for the whole process of postoperative analgesia services. Tongji Hospital affiliated to Tongji Medical College of Huazhong University of Science and Technology has established a professional APS team led by anesthesiologists (TJ-APS), and has a standardized workflow and management system. Based on the TJ-APS standardized postoperative pain management, the incidence and adverse effects of postoperative pain in different types of surgical patients were analyzed. In total, 107,802 patients receiving intravenous PCA from the Tongji Hospital affiliated to Tongji Medical College of Huazhong University of Science and Technology were selected between January 2016 and December 2021, which were under TJ-APS standardized postoperative analgesia process, postoperative analgesia strategy based on the principle of "low opioid, multimodal, specialization and individualization", as well as regular ward rounds and 24-h on call on-duty system. We assessed the incidence and adverse effects of postoperative pain in different types of surgical patients. Based on the TJ-APS standardized postoperative pain management, the incidence of poor postoperative analgesia in patients with intravenous PCA is significantly lower than that reported in the current literature (20 %), and mainly occurs in biliary-pancreatic surgery, extrahepatic surgery and gastrointestinal surgery. The overall incidence of adverse effects was 5.52 %, of which nausea and vomiting was the highest, especially among gynecological tumors and gynecological patients, which were 10.75 % and 8.68 % respectively, but both were lower than the level reported in the current literature (20 %). This APS multimodal management and analgesia process can provide reference and guidance for PCA management of postoperative acute pain.

Ti3C2Tx MXene-Decorated 3D-Printed Ceramic Scaffolds for Enhancing Osteogenesis by Spatiotemporally Orchestrating Inflammatory and Bone Repair Responses.

Inflammatory responses play a central role in coordinating biomaterial-mediated tissue regeneration. However, precise modulation of dynamic variations in microenvironmental inflammation post-implantation remains challenging. In this study, the traditional ß-tricalcium phosphate-based scaffold is remodeled via ultrathin MXene-Ti3C2 decoration and Zn2+/Sr2+ ion-substitution, endowing the scaffold with excellent reactive oxygen species-scavenging ability, near-infrared responsivity, and enhanced mechanical properties. The induction of mild hyperthermia around the implant via periodic near-infrared irradiation facilitates spatiotemporal regulation of inflammatory cytokines secreted by a spectrum of macrophage phenotypes. The process initially amplifies the pro-inflammatory response, then accelerates M1-to-M2 macrophage polarization transition, yielding a satisfactory pattern of osteo-immunomodulation during the natural bone healing process. Later, sustained release of Zn2+/Sr2+ ions with gradual degradation of the 3D scaffold maintains the favorable reparative M2-dominated immunological microenvironment that supports new bone mineralization. Precise temporal immunoregulation of the bone healing process by the intelligent 3D scaffold enhances bone regeneration in a rat cranial defect model. This strategy paves the way for the application of ß-tricalcium phosphate-based materials to guide the dynamic inflammatory and bone tissue responses toward a favorable outcome, making clinical treatment more predictable and durable. The findings also demonstrate that near-infrared irradiation-derived mild hyperthermia is a promising method of immunomodulation.

Exosomes loaded a smart bilayer-hydrogel scaffold with ROS-scavenging and macrophage-reprogramming properties for repairing cartilage defect.

Enhancing the regeneration of cartilage defects remains challenging owing to limited innate self-healing as well as acute inflammation arising from the overexpression of reactive oxygen species (ROS) in post-traumatic microenvironments. Recently, stem cell-derived exosomes (Exos) have been developed as potential cell-free therapy for cartilage regeneration. Although this approach promotes chondrogenesis, it neglects the emerging inflammatory microenvironment. In this study, a smart bilayer-hydrogel dual-loaded with sodium diclofenac (DC), an anti-inflammatory drug, and Exos from bone marrow-derived mesenchymal stem cells was developed to mitigate initial-stage inflammation and promote late-stage stem-cell recruitment and chondrogenic differentiation. First, the upper-hydrogel composed of phenylboronic-acid-crosslinked polyvinyl alcohol degrades in response to elevated levels of ROS to release DC, which mitigates oxidative stress, thus reprogramming macrophages to the pro-healing state. Subsequently, Exos are slowly released from the lower-hydrogel composed of hyaluronic acid into an optimal microenvironment for the stimulation of chondrogenesis. Both in vitro and in vivo assays confirmed that the dual-loaded bilayer-hydrogel reduced post-traumatic inflammation and enhanced cartilage regeneration by effectively scavenging ROS and reprogramming macrophages. The proposed platform provides multi-staged therapy, which allows for the optimal harnessing of Exos as a therapeutic for cartilage regeneration.