Novel multifunctional delivery system for chondrocytes and articular cartilage based on carbon quantum dots

The development of multicolor carbon dots and their applications in the field of anti-counterfeiting

The diversity of photoluminescence emission of multicolor carbon dots (mCDs) greatly broadens their application field. Counterfeiting is a problem that has serious consequences for individuals and society. The fluorescent ink based on mCDs has been developed due to their low toxicity and good resistance to photobleaching in the field of anti-counterfeiting. In the background, the preparation strategies of mCDs were discussed in detail, including top-down method and bottom-up method. The common carbon sources for the preparation of mCDs were further summarized, such as phenylenediamine class, amino-substituted naphthalene class, dihydroxyhenzene and benzoquinone class, biomass, and other common carbon sources. Furthermore, in order to understand the structure of CDs, this paper focused on the classification and common characterization techniques of CDs. In addition, the application of mCDs as fluorescent ink in the field of anti-counterfeiting was classified by simple anti-counterfeiting and good multiple anti-counterfeiting. Finally, the paper offered insight into the future development prospects of CDs-based fluorescent ink based on the current development trends.

A pH-responsive novel delivery system utilizing carbon quantum dots loaded with PT2385 for targeted inhibition of HIF-2α in the treatment of osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a progressive joint disorder marked by the degradation of cartilage. Elevated concentrations of hypoxia-inducible factor-2α (HIF-2α) are intricately linked to the pathological development of OA. PT2385 has demonstrated effective inhibition of HIF-2α, thereby potentially impeding the initial advancement of OA. Nevertheless, challenges persist, including limited penetration into the deeper layers of cartilage, issues related to charge rejection, and a heightened rate of clearance from the joint. These constraints necessitate further consideration and exploration.

METHODS

It has been demonstrated that PT2385 exhibits efficient inhibition of HIF-2α expression, thereby contributing to the delay in the progression of osteoarthritis. The pH-responsive attributes of carbon quantum dots, specifically those employing m-phenylenediamine (m-CQDs) coated with bovine serum albumin (BSA), have been systematically evaluated. In both in vitro settings involving cartilage explants and in vivo experiments, the efficacy of BSA-m-CQDs-PT2385 (BCP) has been confirmed in facilitating the transport of PT2385 to the middle and deep layers of cartilage. Furthermore, the BCP system demonstrates controlled drug release contingent upon alterations in environmental pH.

RESULTS

While the use of PT2385 alone provides protective effects on chondrocytes within an inflamed environment, there exists an opportunity for further enhancement in its efficacy when administered via intra-articular injection. The BCP formulation, characterized by appropriate particle size and charge, facilitates seamless penetration into cartilage tissue. Additionally, BCP demonstrates the capability to release drugs in response to changes in environmental pH. In vitro experiments reveal that BCP effectively inhibits Hif-2α expression and catabolic factors in chondrocytes. Notably, cartilage explants and in vivo experiments indicate that BCP surpasses PT2385 alone in inhibiting the expression of HIF-2α and matrix metalloproteinase 13, particularly in the middle and deep layers.

CONCLUSIONS

The BCP drug delivery system exhibits selective release of PT2385 in response to pH changes occurring during the progression of osteoarthritis (OA), thereby inhibiting HIF-2α expression deep within the cartilage. The use of BCP significantly augments the capacity of PT2385 to retard both cartilage degeneration and the progression of osteoarthritis. Consequently, BCP as an innovative approach utilizing m-CQDs to deliver PT2385 into articular cartilage, shows potential for treating osteoarthritis.This strategy opens new avenues for osteoarthritis treatment.

Quantum dots for bone tissue engineering

In confronting the global prevalence of bone-related disorders, bone tissue engineering (BTE) has developed into a critical discipline, seeking innovative materials to revolutionize treatment paradigms. Quantum dots (QDs), nanoscale semiconductor particles with tunable optical properties, are at the cutting edge of improving bone regeneration. This comprehensive review delves into the multifaceted roles that QDs play within the realm of BTE, emphasizing their potential to not only revolutionize imaging but also to osteogenesis, drug delivery, antimicrobial strategies and phototherapy. The customizable nature of QDs, attributed to their size-dependent optical and electronic properties, has been leveraged to develop precise imaging modalities, enabling the visualization of bone growth and scaffold integration at an unprecedented resolution. Their nanoscopic scale facilitates targeted drug delivery systems, ensuring the localized release of therapeutics. QDs also possess the potential to combat infections at bone defect sites, preventing and improving bacterial infections. Additionally, they can be used in phototherapy to stimulate important bone repair processes and work well with the immune system to improve the overall healing environment. In combination with current trendy artificial intelligence (AI) technology, the development of bone organoids can also be combined with QDs. While QDs demonstrate considerable promise in BTE, the transition from laboratory research to clinical application is fraught with challenges. Concerns regarding the biocompatibility, long-term stability of QDs within the biological environment, and the cost-effectiveness of their production pose significant hurdles to their clinical adoption. This review summarizes the potential of QDs in BTE and highlights the challenges that lie ahead. By overcoming these obstacles, more effective, efficient, and personalized bone regeneration strategies will emerge, offering new hope for patients suffering from debilitating bone diseases.

Biomechanical properties of articular cartilage in different regions and sites of the knee joint: acquisition of osteochondral allografts

Osteochondral allograft (OCA) transplantation involves grafting of natural hyaline cartilage and supporting subchondral bone into the cartilage defect area to restore its biomechanical and tissue structure. However, differences in biomechanical properties and donor-host matching may impair the integration of articular cartilage (AC). This study analyzed the biomechanical properties of the AC in different regions of different sites of the knee joint and provided a novel approach to OCA transplantation. Intact stifle joints from skeletally mature pigs were collected from a local abattoir less than 8 h after slaughter. OCAs were collected from different regions of the joints. The patella and the tibial plateau were divided into medial and lateral regions, while the trochlea and femoral condyle were divided into six regions. The OCAs were analyzed and compared for Young's modulus, the compressive modulus, and cartilage thickness. Young's modulus, cartilage thickness, and compressive modulus of OCA were significantly different in different regions of the joints. A negative correlation was observed between Young's modulus and the proportion of the subchondral bone (r =  - 0.4241, P < 0.0001). Cartilage thickness was positively correlated with Young's modulus (r = 0.4473, P < 0.0001) and the compressive modulus (r = 0.3678, P < 0.0001). During OCA transplantation, OCAs should be transplanted in the same regions, or at the closest possible regions to maintain consistency of the biomechanical properties and cartilage thickness of the donor and recipient, to ensure smooth integration with the surrounding tissue. A 7 mm depth achieved a higher Young's modulus, and may represent the ideal length.

Regulating Chondro-Bone Metabolism for Treatment of Osteoarthritis via High-Permeability Micro/Nano Hydrogel Microspheres

Destruction of cartilage due to the abnormal remodeling of subchondral bone (SB) leads to osteoarthritis (OA), and restoring chondro-bone metabolic homeostasis is the key to the treatment of OA. However, traditional intra-articular injections for the treatment of OA cannot directly break through the cartilage barrier to reach SB. In this study, the hydrothermal method is used to synthesize ultra-small size (≈5 nm) selenium-doped carbon quantum dots (Se-CQDs, SC), which conjugated with triphenylphosphine (TPP) to create TPP-Se-CQDs (SCT). Further, SCT is dynamically complexed with hyaluronic acid modified with aldehyde and methacrylic anhydride (AHAMA) to construct highly permeable micro/nano hydrogel microspheres (SCT@AHAMA) for restoring chondro-bone metabolic homeostasis. In vitro experiments confirmed that the selenium atoms scavenged reactive oxygen species (ROS) from the mitochondria of mononuclear macrophages, inhibited osteoclast differentiation and function, and suppressed early chondrocyte apoptosis to maintain a balance between cartilage matrix synthesis and catabolism. In vivo experiments further demonstrated that the delivery system inhibited osteoclastogenesis and H-vessel invasion, thereby regulating the initiation and process of abnormal bone remodeling and inhibiting cartilage degeneration in SB. In conclusion, the micro/nano hydrogel microspheres based on ultra-small quantum dots facilitate the efficient penetration of articular SB and regulate chondro-bone metabolism for OA treatment.

Multifunctional Carbon Dots for Biomedical Applications: Diagnosis, Therapy, and Theranostic

Designing suitable nanomaterials is an ideal strategy to enable early diagnosis and effective treatment of diseases. Carbon dots (CDs) are luminescent carbonaceous nanoparticles that have attracted considerable attention. Through facile synthesis, they process properties including tunable light emission, low toxicity, and light energy transformation, leading to diverse applications as optically functional materials in biomedical fields. Recently, their potentials have been further explored, such as enzyme-like activity and ability to promote osteogenic differentiation. Through refined synthesizing strategies carbon dots, a rich treasure trove for new discoveries, stand a chance to guide significant development in biomedical applications. In this review, the authors start with a brief introduction to CDs. By presenting mechanisms and examples, the authors focus on how they can be used in diagnosing and treating diseases, including bioimaging failure of tissues and cells, biosensing various pathogenic factors and biomarkers, tissue defect repair, anti-inflammation, antibacterial and antiviral, and novel oncology treatment. The introduction of the application of integrated diagnosis and treatment follows closely behind. Furthermore, the challenges and future directions of CDs are discussed. The authors hope this review will provide critical perspectives to inspire new discoveries on CDs and prompt their advances in biomedical applications.

Injectable hydrogels for cartilage and bone tissue regeneration: A review

Annually, millions of patients suffer from irreversible injury owing to the loss or failure of an organ or tissue caused by accident, aging, or disease. The combination of injectable hydrogels and the science of stem cells have emerged to address this persistent issue in society by generating minimally invasive treatments to augment tissue function. Hydrogels are composed of a cross-linked network of polymers that exhibit a high-water retention capacity, thereby mimicking the wet environment of native cells. Due to their inherent mechanical softness, hydrogels can be used as needle-injectable stem cell carrier materials to mend tissue defects. Hydrogels are made of different natural or synthetic polymers, displaying a broad portfolio of eligible properties, which include biocompatibility, low cytotoxicity, shear-thinning properties as well as tunable biological and physicochemical properties. Presently, novel ongoing developments and native-like hydrogels are increasingly being used broadly to improve the quality of life of those with disabling tissue-related diseases. The present review outlines various future and in-vitro applications of injectable hydrogel-based biomaterials, focusing on the newest ongoing developments of in-situ forming injectable hydrogels for bone and cartilage tissue engineering purposes.

Duplex-immunoassay of ovarian cancer biomarker CA125 and HE4 based carbon dot decorated dendritic mesoporous silica nanoparticles

Fluorescent lateral flow immunoassay (FLFIA) is widely used mainly because of its low cost and instant detection. Its limit of detection (LOD) is closely related to fluorescence signals, and the development of fluorescence signals with fine performance remains a challenge. In this work, dendritic mesoporous silica nanoparticles (DMSNs) were used as fine carriers due to their large pore size and stable performance. We successfully synthesized carbon dots (CDs) with a 560 nm maximum emission wavelength (CD₅₆₀) by the hydrothermal method. A new type of fluorescence signal for FLFIA was observed by loading CD₅₆₀ on DMSNs through the Si-O bond which is denoted as DMSNs@CD₅₆₀. Applying DMSNs@CD₅₆₀ to the FLFIA can eliminate the influence of interfacial background blue fluorescence thus improving its detection sensitivity. The formed DMSNs@CD₅₆₀-FLFIA achieved high sensitivity detection of ovarian cancer biomarkers carbohydrate antigen 125 (CA125) and human epididymal protein 4 (HE4). The LOD of CA125 is 0.5 U mL^-1 and the correlation coefficient R² = 0.985, and the LOD of HE4 reaches 0.05 ng mL^-1 and the correlation coefficient R² = 0.981. The DMSNs@CD₅₆₀-FLFIA is sensitive and efficient providing a new method for the early diagnosis of ovarian cancer.