Composited silk fibroins ensured adhesion stability and magnetic controllability of Fe3O4-nanoparticle coating on implant for biofilm treatment.

Magnetic propulsion of nano-/micro-robots is an effective way to treat implant-associated infections by physically destroying biofilm structures to enhance antibiotic killing. However, it is hard to precisely control the propulsion in vivo. Magnetic-nanoparticle coating that can be magnetically pulled off does not need precise control, but the requirement of adhesion stability on an implant surface restricts its magnetic responsiveness. Moreover, whether the coating has been fully pulled-off or not is hard to ensure in real-time in vivo. Herein, composited silk fibroins (SFMA) are optimized to stabilize Fe3O4 nanoparticles on a titanium surface in a dry environment; while in an aqueous environment, the binding force of SFMA on titanium is significantly reduced due to hydrophilic interaction, making the coating magnetically controllable by an externally-used magnet but still stable in the absence of a magnet. The maximum working distance of the magnet can be calculated using magnetomechanical simulation in which the yielding magnetic traction force is strong enough to pull Fe3O4 nanoparticles off the surface. The pulling-off removes the biofilms that formed on the coating and enhances antibiotic killing both in vitro and in a rat sub-cutaneous implant model by up to 100 fold. This work contributes to the practical knowledge of magnetic propulsion for biofilm treatment.

Engineering Large-Scale Self-Mineralizing Bone Organoids with Bone Matrix-Inspired Hydroxyapatite Hybrid Bioinks.

Addressing large bone defects remains a significant challenge owing to the inherent limitations in self-healing capabilities, resulting in prolonged recovery and suboptimal regeneration. Although current clinical solutions are available, they have notable shortcomings, necessitating more efficacious approaches to bone regeneration. Organoids derived from stem cells show great potential in this field; however, the development of bone organoids has been hindered by specific demands, including the need for robust mechanical support provided by scaffolds and hybrid extracellular matrices (ECM). In this context, bioprinting technologies have emerged as powerful means of replicating the complex architecture of bone tissue. The research focused on the fabrication of a highly intricate bone ECM analog using a novel bioink composed of gelatin methacrylate/alginate methacrylate/hydroxyapatite (GelMA/AlgMA/HAP). Bioprinted scaffolds facilitate the long-term cultivation and progressive maturation of extensive bioprinted bone organoids, foster multicellular differentiation, and offer valuable insights into the initial stages of bone formation. The intrinsic self-mineralizing quality of the bioink closely emulates the properties of natural bone, empowering organoids with enhanced bone repair for both in vitro and in vivo applications. This trailblazing investigation propels the field of bone tissue engineering and holds significant promise for its translation into practical applications.

AI energized hydrogel design, optimization and application in biomedicine.

Traditional hydrogel design and optimization methods usually rely on repeated experiments, which is time-consuming and expensive, resulting in a slow-moving of advanced hydrogel development. With the rapid development of artificial intelligence (AI) technology and increasing material data, AI-energized design and optimization of hydrogels for biomedical applications has emerged as a revolutionary breakthrough in materials science. This review begins by outlining the history of AI and the potential advantages of using AI in the design and optimization of hydrogels, such as prediction and optimization of properties, multi-attribute optimization, high-throughput screening, automated material discovery, optimizing experimental design, and etc. Then, we focus on the various applications of hydrogels supported by AI technology in biomedicine, including drug delivery, bio-inks for advanced manufacturing, tissue repair, and biosensors, so as to provide a clear and comprehensive understanding of researchers in this field. Finally, we discuss the future directions and prospects, and provide a new perspective for the research and development of novel hydrogel materials for biomedical applications.

Heterogeneous DNA hydrogel loaded with Apt02 modified tetrahedral framework nucleic acid accelerated critical-size bone defect repair.

Segmental bone defects, stemming from trauma, infection, and tumors, pose formidable clinical challenges. Traditional bone repair materials, such as autologous and allogeneic bone grafts, grapple with limitations including source scarcity and immune rejection risks. The advent of nucleic acid nanotechnology, particularly the use of DNA hydrogels in tissue engineering, presents a promising solution, attributed to their biocompatibility, biodegradability, and programmability. However, these hydrogels, typically hindered by high gelation temperatures (∼46 °C) and high construction costs, limit cell encapsulation and broader application. Our research introduces a novel polymer-modified DNA hydrogel, developed using nucleic acid nanotechnology, which gels at a more biocompatible temperature of 37 °C and is cost-effective. This hydrogel then incorporates tetrahedral Framework Nucleic Acid (tFNA) to enhance osteogenic mineralization. Furthermore, considering the modifiability of tFNA, we modified its chains with Aptamer02 (Apt02), an aptamer known to foster angiogenesis. This dual approach significantly accelerates osteogenic differentiation in bone marrow stromal cells (BMSCs) and angiogenesis in human umbilical vein endothelial cells (HUVECs), with cell sequencing confirming their targeting efficacy, respectively. In vivo experiments in rats with critical-size cranial bone defects demonstrate their effectiveness in enhancing new bone formation. This innovation not only offers a viable solution for repairing segmental bone defects but also opens avenues for future advancements in bone organoids construction, marking a significant advancement in tissue engineering and regenerative medicine.

Boosting cartilage repair with silk fibroin-DNA hydrogel-based cartilage organoid precursor.

Osteoarthritis (OA), a common degenerative disease, is characterized by high disability and imposes substantial economic impacts on individuals and society. Current clinical treatments remain inadequate for effectively managing OA. Organoids, miniature 3D tissue structures from directed differentiation of stem or progenitor cells, mimic native organ structures and functions. They are useful for drug testing and serve as active grafts for organ repair. However, organoid construction requires extracellular matrix-like 3D scaffolds for cellular growth. Hydrogel microspheres, with tunable physical and chemical properties, show promise in cartilage tissue engineering by replicating the natural microenvironment. Building on prior work on SF-DNA dual-network hydrogels for cartilage regeneration, we developed a novel RGD-SF-DNA hydrogel microsphere (RSD-MS) via a microfluidic system by integrating photopolymerization with self-assembly techniques and then modified with Pep-RGDfKA. The RSD-MSs exhibited uniform size, porous surface, and optimal swelling and degradation properties. In vitro studies demonstrated that RSD-MSs enhanced bone marrow mesenchymal stem cells (BMSCs) proliferation, adhesion, and chondrogenic differentiation. Transcriptomic analysis showed RSD-MSs induced chondrogenesis mainly through integrin-mediated adhesion pathways and glycosaminoglycan biosynthesis. Moreover, in vivo studies showed that seeding BMSCs onto RSD-MSs to create cartilage organoid precursors (COPs) significantly enhanced cartilage regeneration. In conclusion, RSD-MS was an ideal candidate for the construction and long-term cultivation of cartilage organoids, offering an innovative strategy and material choice for cartilage regeneration and tissue engineering.

Novel Synthesis Approach for Natural Tea Polyphenol-Integrated Hydroxyapatite.

Hydroxyapatite (HAP) has garnered considerable interest in biomedical engineering for its diverse applications. Yet, the synthesis of HAP integrated with functional natural organic components remains an area ripe for exploration. This study innovatively utilizes the versatile properties of tea polyphenol (TP) to synthesize HAP nanomaterials with superior crystallinity and distinct morphologies, notably rod-like structures, via a chemical deposition process in a nitrogen atmosphere. This method ensures an enhanced integration of TP, as confirmed by thermogravimetric (TGA) analysis and a variety of microscopy techniques, which also reveal the dependence of TP content and crystallinity on the synthesis method employed. The research significantly impacts the field by demonstrating how synthesis conditions can alter material properties. It leads the way in employing TP-modified nano-HAP particles for biomedical applications. The findings of this study are crucial as they open avenues for the future development of tailored HAP nanomaterials, aiming at specific medical applications and advancements in nanotechnology.

Dual-network DNA-silk fibroin hydrogels with controllable surface rigidity for regulating chondrogenic differentiation.

Osteoarthritis (OA) is a common joint disease known for cartilage degeneration, leading to a substantial burden on individuals and society due to its high disability rate. However, current clinical treatments for cartilage defects remain unsatisfactory due to the unclear mechanisms underlying cartilage regeneration. Tissue engineering hydrogels have emerged as an attractive approach in cartilage repair. Recent research studies have indicated that stem cells can sense the mechanical strength of hydrogels, thereby regulating their differentiation fate. In this study, we present the groundbreaking construction of dual-network DNA-silk fibroin (SF) hydrogels with controllable surface rigidity. The supramolecular networks, formed through DNA base-pairing, induce the development of ß-sheet structures by constraining and aggregating SF molecules. Subsequently, SF was cross-linked via horseradish peroxidase (HRP)-mediated enzyme reactions to form the second network. Experimental results demonstrated a positive correlation between the surface rigidity of dual-network DNA-SF hydrogels and the DNA content. Interestingly, it was observed that dual-network DNA-SF hydrogels with moderate surface rigidity exhibited the highest effectiveness in facilitating the migration of bone marrow mesenchymal stem cells (BMSCs) and their chondrogenic differentiation. Transcriptome sequencing further confirmed that dual-network DNA-SF hydrogels primarily enhanced chondrogenic differentiation of BMSCs by upregulating the Wnt and TGF-ß signaling pathways while accelerating collagen II synthesis. Furthermore, in vivo studies revealed that dual-network DNA-SF hydrogels with moderate surface rigidity significantly accelerated cartilage regeneration. In summary, the dual-network DNA-SF hydrogels represent a promising and novel therapeutic strategy for cartilage regeneration.

Small Joint Organoids 3D Bioprinting: Construction Strategy and Application.

Osteoarthritis (OA) is a chronic disease that causes pain and disability in adults, affecting ≈300 million people worldwide. It is caused by damage to cartilage, including cellular inflammation and destruction of the extracellular matrix (ECM), leading to limited self-repairing ability due to the lack of blood vessels and nerves in the cartilage tissue. Organoid technology has emerged as a promising approach for cartilage repair, but constructing joint organoids with their complex structures and special mechanisms is still challenging. To overcome these boundaries, 3D bioprinting technology allows for the precise design of physiologically relevant joint organoids, including shape, structure, mechanical properties, cellular arrangement, and biological cues to mimic natural joint tissue. In this review, the authors will introduce the biological structure of joint tissues, summarize key procedures in 3D bioprinting for cartilage repair, and propose strategies for constructing joint organoids using 3D bioprinting. The authors also discuss the challenges of using joint organoids' approaches and perspectives on their future applications, opening opportunities to model joint tissues and response to joint disease treatment.

Bone-Targeted Exosomes: Strategies and Applications.

As the global population ages, bone-related diseases have increasingly become a major social problem threatening human health. Exosomes, as natural cell products, have been used to treat bone-related diseases due to their superior biocompatibility, biological barrier penetration, and therapeutic effects. Moreover, the modified exosomes exhibit strong bone-targeting capabilities that may improve efficacy and avoid systemic side effects, demonstrating promising translational potential. However, a review of bone-targeted exosomes is still lacking. Thus, the recently developed exosomes for bone-targeting applications in this review are focused. The biogenesis and bone-targeting regulatory functions of exosomes, the constructive strategies of modified exosomes to improve bone-targeting, and their therapeutic effects for bone-related diseases are introduced. By summarizing developments and challenges in bone-targeted exosomes, It is striven to shed light on the selection of exosome constructive strategies for different bone diseases and highlight their translational potential for future clinical orthopedics.

Selection and identification of a novel ssDNA aptamer targeting human skeletal muscle.

Skeletal muscle disorders have posed great threats to health. Selective delivery of drugs and oligonucleotides to skeletal muscle is challenging. Aptamers can improve targeting efficacy. In this study, for the first time, the human skeletal muscle-specific ssDNA aptamers (HSM01, etc.) were selected and identified with Systematic Evolution of Ligands by Exponential Enrichment (SELEX). The HSM01 ssDNA aptamer preferentially interacted with human skeletal muscle cells in vitro. The in vivo study using tree shrews showed that the HSM01 ssDNA aptamer specifically targeted human skeletal muscle cells. Furthermore, the ability of HSM01 ssDNA aptamer to target skeletal muscle cells was not affected by the formation of a disulfide bond with nanoliposomes in vitro or in vivo, suggesting a potential new approach for targeted drug delivery to skeletal muscles via liposomes. Therefore, this newly identified ssDNA aptamer and nanoliposome modification could be used for the treatment of human skeletal muscle diseases.

Construction of Local Drug Delivery System on Titanium-Based Implants to Improve Osseointegration.

Titanium and its alloys are the most widely applied orthopedic and dental implant materials due to their high biocompatibility, superior corrosion resistance, and outstanding mechanical properties. However, the lack of superior osseointegration remains the main obstacle to successful implantation. Previous traditional surface modification methods of titanium-based implants cannot fully meet the clinical needs of osseointegration. The construction of local drug delivery systems (e.g., antimicrobial drug delivery systems, anti-bone resorption drug delivery systems, etc.) on titanium-based implants has been proved to be an effective strategy to improve osseointegration. Meanwhile, these drug delivery systems can also be combined with traditional surface modification methods, such as anodic oxidation, acid etching, surface coating technology, etc., to achieve desirable and enhanced osseointegration. In this paper, we review the research progress of different local drug delivery systems using titanium-based implants and provide a theoretical basis for further research on drug delivery systems to promote bone-implant integration in the future.

Antimicrobial loading of nanotubular titanium surfaces favoring surface coverage by mammalian cells over bacterial colonization.

Titanium is frequently used for dental implants, percutaneous pins and screws or orthopedic joint prostheses. Implant surfaces can become peri-operatively contaminated by surgically introduced bacteria during implantation causing lack of surface coverage by mammalian cells and subsequent implant failure. Especially implants that have to function in a bacteria-laden environment such as dental implants or percutaneous pins, cannot be surgically implanted while being kept sterile. Accordingly, contaminating bacteria adhering to implant surfaces hamper successful surface coverage by mammalian cells required for long-term functioning. Here, nanotubular titanium surfaces were prepared and loaded with Ag nanoparticles or gentamicin with the aim of killing contaminating bacteria in order to favor surface coverage by mammalian cells. In mono-cultures, unloaded nanotubules did not cause bacterial killing, but loading of Ag nanoparticles or gentamicin reduced the number of adhering Staphylococcus aureus or Pseudomonas aeruginosa CFUs. A gentamicin-resistant Staphylococcus epidermidis was only killed upon loading with Ag nanoparticles. However, unlike low-level gentamicin loading, loading with Ag nanoparticles also caused tissue-cell death. In bi-cultures, low-level gentamicin-loading of nanotubular titanium surfaces effectively eradicated contaminating bacteria favoring surface coverage by mammalian cells. Thus, care must be taken in loading nanotubular titanium surfaces with Ag nanoparticles, while low-level gentamicin-loaded nanotubular titanium surfaces can be used as a local antibiotic delivery system to negate failure of titanium implants due to peri-operatively introduced, contaminating bacteria without hampering surface coverage by mammalian cells.

Safety Evaluation of Natural Drugs in Chronic Skeletal Disorders: A Literature Review of Clinical Trials in the Past 20 years.

Chronic skeletal disorders (CSDs), including degenerative diseases such as osteoporosis (OP) and autoimmune disorders, have become a leading cause of disability in an ageing society, with natural drugs being indispensable therapeutic options. The clinical safety evaluation (CSE) of natural drugs in CSDs has been given priority and has been intensively studied. To provide fundamental evidence for the clinical application of natural drugs in the elderly population, clinical studies of natural drugs in CSDs included in this review were selected from CNKI, Web of Science, PubMed, Science Direct and Google Scholar since 2001. Seventeen randomized controlled trials (RCTs) met our inclusion criteria: four articles were on OP, seven on osteoarthritis (OA), four on rheumatoid arthritis (RA) and two on gout. Common natural drugs used for the treatment of OP include Epimedium brevicornu Maxim [Berberidaceae], Dipsacus asper Wall ex DC [Caprifoliaceae] root, and Phalaenopsis cornu-cervi (Breda) Blume & Rchb. f[ Orchidaceae], which have been linked to several mild adverse reactions, such as skin rash, gastric dysfunction, abnormal urine, constipation and irritability. The safety of Hedera helix L [Araliaceae] extract, Boswellia serrata Roxb [Burseraceae] extract and extract from perna canaliculus was evaluated in OA and upper abdominal pain, and unstable movements were obsrerved as major side effects. Adverse events, including pneumonia, vomiting, diarrhoea and upper respiratory tract infection, were reported when RA was treated with Tripterygium wilfordii, Hook. F [Celastraceae][TwHF] polyglycosides and quercetin (Capsella bursa-pastoris (L.) Medik [Brassicaceae]). The present review aimed to summarize the CSE results of natural drugs in CSDs and could provide evidence-based information for clinicians.

Reactive Oxygen Species (ROS)-Responsive Biomaterials for the Treatment of Bone-Related Diseases.

Reactive oxygen species (ROS) are the key signaling molecules in many physiological signs of progress and are associated with almost all diseases, such as atherosclerosis, aging, and cancer. Bone is a specific connective tissue consisting of cells, fibers, and mineralized extracellular components, and its quality changes with aging and disease. Growing evidence indicated that overproduced ROS accumulation may disrupt cellular homeostasis in the progress of bone modeling and remodeling, leading to bone metabolic disease. Thus, ROS-responsive biomaterials have attracted great interest from many researchers as promising strategies to realize drug release or targeted therapy for bone-related diseases. Herein, we endeavor to introduce the role of ROS in the bone microenvironment, summarize the mechanism and development of ROS-responsive biomaterials, and their completion and potential for future therapy of bone-related diseases.

Natural polysaccharide-incorporated hydroxyapatite as size-changeable, nuclear-targeted nanocarrier for efficient cancer therapy.

Targeted delivery of anticancer drugs is one of the most promising methods for cancer therapy. However, barriers including complicated procedures, costly preparation, and toxic side effects have restricted the development of nuclear-targeted nanocarriers. Natural polysaccharides as extracellular matrix constituents or analogs play an important role in biomineralization. Herein, a simple, polysaccharide-intervened preparation of hydroxyapatite (HA) hybrid nanoparticles (NPs) with low crystallinity was used as a bio-safe carrier for targeting the delivery of doxorubicin (DOX) for efficient anticancer therapy. The poorly crystallized hybrid HA NPs were specifically taken up by cancer cells (HeLa cells), and subsequently, the abrupt degradation of HA nanoparticles would cause a change in the osmotic pressure, leading to the explosive death of cancer cells. Furthermore, the hybrid HA NPs were size changeable and capable of directly delivering the anti-cancer drug into the nucleus of cancer cells, thereby efficiently killing cancer cells. In addition, the HA/ALG NPs reduce the toxicity of DOX to L929 cells and cause little negative effect on normal tissue cells. The in vitro and in vivo experiments confirmed that the size-changeable HA-ALG/DOX could be a promising nuclear-targeted delivery nanocarrier for efficient cancer therapy.

Eradicating Infecting Bacteria while Maintaining Tissue Integration on Photothermal Nanoparticle-Coated Titanium Surfaces.

Photothermal nanoparticles locally release heat when irradiated by near-infrared (NIR). Clinical applications initially involved tumor treatment, but currently extend toward bacterial infection control. Applications toward much smaller, micrometer-sized bacterial infections, however, bear the risk of collateral damage by dissipating heat into tissues surrounding an infection site. This can become a complication when photothermal nanoparticle coatings are clinically applied on biomaterial surfaces requiring tissue integration, such as titanium-made, bone-anchored dental implants. Dental implants can fail due to infection in the pocket formed between the implant screw and the surrounding soft tissue ("peri-implantitis"). We address the hitherto neglected potential complication of collateral tissue damage by evaluating photothermal, polydopamine nanoparticle (PDA-NP) coatings on titanium surfaces in different coculture models. NIR irradiation of PDA-NP-coated (200 µg/cm2) titanium surfaces with adhering Staphylococcus aureus killed staphylococci within an irradiation time window of around 3 min. Alternatively, when covered with human gingival fibroblasts, this irradiation time window maintained surface coverage by fibroblasts. Contaminating staphylococci on PDA-NP-coated titanium surfaces, as can be per-operatively introduced, reduced surface coverage by fibroblasts, and this could be prevented by NIR irradiation for 5 min or longer prior to allowing fibroblasts to adhere and grow. Negative impacts of early postoperative staphylococcal challenges to an existing fibroblast layer covering a coated surface were maximally prevented by 3 min NIR irradiation. Longer irradiation times caused collateral fibroblast damage. Late postoperative staphylococcal challenges to a protective keratinocyte layer covering a fibroblast layer required 10 min NIR irradiation for adverting a staphylococcal challenge. This is longer than foreseen from monoculture studies because of additional heat uptake by the keratinocyte layer. Summarizing, photothermal treatment of biomaterial-associated infection requires precise timing of NIR irradiation to prevent collateral damage to tissues surrounding the infection site.

Artificial Channels in an Infectious Biofilm Created by Magnetic Nanoparticles Enhanced Bacterial Killing by Antibiotics.

The poor penetrability of many biofilms contributes to the recalcitrance of infectious biofilms to antimicrobial treatment. Here, a new application for the use of magnetic nanoparticles in nanomedicine to create artificial channels in infectious biofilms to enhance antimicrobial penetration and bacterial killing is proposed. Staphylococcus aureus biofilms are exposed to magnetic-iron-oxide nanoparticles (MIONPs), while magnetically forcing MIONP movement through the biofilm. Confocal laser scanning microscopy demonstrates artificial channel digging perpendicular to the substratum surface. Artificial channel digging significantly (4-6-fold) enhances biofilm penetration and bacterial killing efficacy by gentamicin in two S. aureus strains with and without the ability to produce extracellular polymeric substances. Herewith, this work provides a simple, new, and easy way to enhance the eradication of infectious biofilms using MIONPs combined with clinically applied antibiotic therapies.

Keratinocytes protect soft-tissue integration of dental implant materials against bacterial challenges in a 3D-tissue infection model.

The soft-tissue seal around dental implants protects the osseo-integrated screw against bacterial challenges. Surface properties of the implant material are crucial for implant survival against bacterial challenges, but there is no adequate in vitro model mimicking the soft-tissue seal around dental implants. Here, we set up a 3D-tissue model of the soft-tissue seal, in order to establish the roles of oral keratinocytes, gingival fibroblasts and materials surface properties in the protective seal. To this end, keratinocytes were grown on membrane filters in a transwell system, while fibroblasts were adhering to TiO2 surfaces underneath the membrane. In absence of keratinocytes on the membrane, fibroblasts growing on the TiO2 surface could not withstand challenges by commensal streptococci or pathogenic staphylococci. Keratinocytes growing on the membrane filters could withstand bacterial challenges, but tight junctions widened to allow invasion of bacteria to the underlying fibroblast layer in lower numbers than in absence of keratinocytes. The challenge of this bacterial invasion to the fibroblast layer on the TiO2 surface negatively affected tissue integration of the surface, demonstrating the protective barrier role of keratinocytes. Streptococci caused less damage to fibroblasts than staphylococci. Importantly, the protection offered by the soft-tissue seal appeared sensitive to surface properties of the implant material. Integration by fibroblasts of a hydrophobic silicone rubber surface was affected more upon bacterial challenges than integration of more hydrophilic hydroxyapatite or TiO2 surfaces. This differential response to different surface-chemistries makes the 3D-tissue infection model presented a useful tool in the development of new infection-resistant dental implant materials. STATEMENT OF SIGNIFICANCE: Failure rates of dental implants due to infection are surprisingly low, considering their functioning in the highly un-sterile oral cavity. This is attributed to the soft-tissue seal, protecting the osseo-integrated implant part against bacterial invasion. The seal consists of a layer of keratinocytes covering gingival fibroblasts, integrating the implant. Implant failure involves high patient discomfort and costs of replacing an infected implant, which necessitates development of improved, infection-resistant dental implant materials. New materials are often evaluated in mono-culture, examining bacterial adhesion or tissue interactions separately and neglecting the 3D-structure of the tissue seal. A 3D-tissue model allows to study new materials in a more relevant way, in which interactions between keratinocytes, gingival fibroblast, bacteria and materials surfaces are accounted for.

Tumor-targeted and nitric oxide-generated nanogels of keratin and hyaluronan for enhanced cancer therapy.

The development of safe and effective nano-drug delivery systems to deliver anticancer drugs to targeted cells and organs is crucial to enhance the therapeutic efficacy and overcome unwanted side effects of chemotherapy. Herein, we prepared CD44-targeted dual-stimuli responsive human hair keratin and hyaluronic acid nanogels (KHA-NGs) through a simple crosslinking method. KHA-NGs, which consisted of spheres 50 nm in diameter, were used as carriers to load the anticancer drug doxorubicin hydrochloride (DOX). The drug release, cellular uptake, cytotoxicity, and targeting ability of DOX-loaded KHA-NGs (DOX@KHA-NGs) were assessed in vitro and the anticancer effects were further evaluated in vivo. The DOX@KHA-NGs had a super-high drug loading capacity (54.1%, w/w) and were stable under physiological conditions (10 µM glutathione (GSH)), with the drug being rapidly released under a tumor cell microenvironment of trypsin and 10 mM GSH. Cellular uptake and in vitro cytotoxicity results indicated that DOX@KHA-NGs specifically targeted cancer cells and effectively inhibited their growth. Furthermore, KHA-NGs were capable of improving intracellular nitric oxide levels, which sensitizes the cells and enhances the anticancer efficacy of chemotherapeutic drugs. In vivo experiments showed that DOX@KHA-NGs had a better anti-tumor effect and lower side effects compared to free DOX. These results suggest that the bio-responsive KHA-NGs have potential applications for targeted cancer therapy.

Alginate-Mediated Mineralization for Ultrafine Hydroxyapatite Hybrid Nanoparticles.

The good bioactivity of hydroxyapatite (HA) makes it become a popular biomaterial, and so, the synthesis of HA has attracted much attention. However, a simple method to prepare well-dispersive and ultrafine HA nanoparticles (NPs) still needs to be explored. Here, needle-like hybrid HA NPs were synthesized in the presence of alginate (ALG) and the mechanism of ALG regulation on forming HA/ALG hybrid NPs was investigated. The size and crystallinity of HA/ALG NPs could be controlled simply by varying the amount of ALG. With a higher concentration of ALG, the size of HA/ALG NPs reduced and their dispersity was further improved. The assembly with ca. 3-6 nm thick nanoneedles was discernible in HA/ALG NPs. The results collected by Ca2+ concentration, pH, and conductometric measurements further provided the supportive data for ALG inhibition of calcium phosphate compound formation and thus modulation of HA crystallization. In addition, the good biocompatibility of synthesized HA/ALG NPs was indicated from the results of CCK-8 assays and CLSM observations after cultured with L929 cells. The needle-like HA NPs are promising for varied biomedical purposes, and their potential application as drug carriers would be further studied.