Yong-Gang Zhang

Sonochemical synthesis of hydroxyapatite nanoflowers using creatine phosphate disodium salt as an organic phosphorus source and their application in protein adsorption

In this paper, the one-step rapid synthesis of hydroxyapatite nanoflowers (HAFs) using creatine phosphate disodium salt as an organic phosphorus source by the sonochemical method is reported. The HAFs with diameters of about 300 nm are formed by self-assembly of hydroxyapatite nanosheets with thicknesses of less than 10 nm. The as-prepared samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET) nitrogen sorptometry, X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and inductively coupled plasma (ICP) optical emission spectroscopy. The MTT tests show that the as-prepared HAFs exhibit essentially inappreciable toxicity to MC-3T3 osteoblast cells, indicating that the HAFs have an excellent cytocompatibility. Moreover, the as-prepared HAFs show a relatively high protein adsorption ability when using hemoglobin (Hb) as a model protein. Thus, the as-prepared HAFs are promising for applications in various biomedical fields such as protein/drug delivery.

Templated solvothermal synthesis of magnesium silicate hollow nanospheres with ultrahigh specific surface area and their application in high-performance protein adsorption and drug delivery

Magnesium silicate nanostructured biomaterials with good biocompatibility and high adsorption capacity for drugs and proteins are promising for applications in various biomedical fields. However, the applications of magnesium silicate nanostructured biomaterials in anticancer drug delivery and protein adsorption have rarely been reported so far. Herein, we report a facile strategy for the synthesis of magnesium silicate hollow nanospheres (MSHNSs) by a classical Stöber method and a template based solvothermal process. The as-prepared MSHNSs have an ultrahigh specific surface area of 585.6 m2 g-1, ultrahigh hemoglobin (Hb) protein adsorption capacity (1262 mg g-1) and high doxorubicin (DOX) drug loading capacity (559 mg g-1). Moreover, the as-prepared MSHNS/DOX drug delivery system exhibits sustained and pH-responsive drug release performance. Compared with free DOX, the MSHNS/DOX drug delivery system exhibits higher anticancer activity in vitro, and thus it is promising for applications in anticancer treatment.

Ultralong Hydroxyapatite Nanowires-Based Paper Co-Loaded with Silver Nanoparticles and Antibiotic for Long-Term Antibacterial Benefit

Hydroxyapatite is a kind of biocompatible, environmentally friendly, and versatile inorganic biomaterial. Herein, the preparation of ultralong hydroxyapatite nanowires (HAPNWs)-based antibacterial paper co-loaded with silver nanoparticles (AgNPs) and antibiotic is reported. HAPNWs are used to prepare AgNPs in situ using an aqueous solution containing AgNO3 under the sunlight without added reducing agent at room temperature. Subsequently, ciprofloxacin (CIP) as an antibiotic is loaded on the HAPNWs@AgNPs. The resultant HAPNWs@AgNPs-CIP paper possesses several unique properties, including high flexibility, high Brunauer-Emmett-Teller (BET) specific surface area (47.9 m2 g-1), high drug loading capacity (447.4 mg g-1), good biocompatibility, sustained and pH-responsive drug release behavior (5.40-6.75% of Ag+ ions and 37.7-76.4% of CIP molecules at pH values of 7.4-4.5 at day 8, respectively), and reusable recycling. In the antibacterial tests against Escherichia coli and Staphylococcus aureus, the HAPNWs@AgNPs-CIP paper exhibits large diameters of inhibition zones and low minimum inhibitory concentrations (30 and 40 μg mL-1), revealing the high antibacterial activity. Besides, the consecutive agar diffusion tests (8 cycles), long-term stability tests (over 56 days), and continuous contamination tests (5 cycles) demonstrate the excellent recycling performance and long-term antibacterial activity of the HAPNWs@AgNPs-CIP paper. These results indicate a promising potential of the HAPNWs@AgNPs-CIP bactericidal paper for tackling public health issues related to bacterial infections.

Ultralong Hydroxyapatite Nanowire/Collagen Biopaper with High Flexibility, Improved Mechanical Properties and Excellent Cellular Attachment.

Highly flexible hydroxyapatite/collagen (HAP/Col) composite membranes are regarded to be significant for guided bone regeneration application owing to their similar chemical composition to that of natural bone, excellent bioactivity and good osteoconductivity. However, the mechanical strength of the HAP/Col composite membranes is usually weak, which leads to difficult surgical operations and low mechanical stability during the bone healing process. Herein, highly flexible ultralong hydroxyapatite nanowires/collagen (UHANWs/Col) composite biopaper sheets with weight fractions of UHANWs ranging from 0 to 100 % are facilely synthesized. The UHANWs are able to weave with each other to construct a three-dimensional fabric structure in the collagen matrix, providing a strong interaction between UHANWs and an intermolecular force between UHANWs and the collagen matrix. The as-prepared UHANWs/Col composite biopaper exhibits improved mechanical properties and high flexibility. More importantly, the as-prepared highly flexible 70 wt % UHANWs/Col composite biopaper exhibits an excellent cytocompatibility and outstanding cellular attachment performance as compared with the pure collagen and 70 wt % HAP nanorods/Col membranes. In consideration of its superior mechanical properties and outstanding cellular attachment performance, the as-prepared UHANWs/Col composite biopaper is promising for applications in various biomedical fields such as guided bone regeneration.

Preparation and enhanced mechanical properties of hybrid hydrogels comprising ultralong hydroxyapatite nanowires and sodium alginate

Hydrogels with 3-dimentional cross-linked structures are widely used in various biomedical fields such as bone repair scaffolds, drug carriers and biosensors. However, the applications of hydrogels are usually restricted because of their poor mechanical properties. Currently, nanocomposites, double network systems, hydrophobic association, macromolecules, and nanoparticles are commonly adopted as cross-linking agents to enhance mechanical properties of hydrogels. In this work, ultralong hydroxyapatite nanowires (HANWs) with lengths of several hundred microns are prepared and used to enhance the mechanical properties of sodium alginate (SA)-based hydrogels. Using divalent calcium ions as the cross-linking agent, the hybrid HANWs/SA hydrogels containing various percentages of HANWs are obtained. The as-prepared HANWs/SA hybrid hydrogels have a porous structure with pore sizes ranging from about 200 to 500μm. The mechanical properties of SA hydrogels can be significantly improved by incorporating HANWs. The maximum compressive modulus (E50%) and tensile Youngs modulus of the hybrid hydrogel (HANWs/SA=2:1) are as high as 0.123MPa and 0.994MPa, which are about 162% and 614% those of the pure SA hydrogel, respectively. Due to the enhanced mechanical properties and high biocompatibility, the as-prepared HANWs/SA hybrid hydrogels have promising applications in various biomedical fields such as bone defect repair.

Binary Strengthening and Toughening of MXene/Cellulose Nanofiber Composite Paper with Nacre-Inspired Structure and Superior Electromagnetic Interference Shielding Properties

With the growing popularity of electrical communication equipment, high-performance electromagnetic interference (EMI) shielding materials are widely used to deal with radiation pollution. However, the large thickness and poor mechanical properties of many EMI shielding materials usually limit their applications. In this study, ultrathin and highly flexible Ti3C2T x (d-Ti3C2T x, MXene)/cellulose nanofiber (CNF) composite paper with a nacre-like lamellar structure is fabricated via a vacuum-filtration-induced self-assembly process. By the interaction between one-dimensional (1D) CNFs and two-dimensional (2D) d-Ti3C2T x MXene, the binary strengthening and toughening of the nacre-like d-Ti3C2T x/CNF composite paper has been successfully achieved, leading to high tensile strength (up to 135.4 MPa) and fracture strain (up to 16.7%), as well as excellent folding endurance (up to 14 260 times). Moreover, the d-Ti3C2T x/CNF composite paper exhibits high electrical conductivity (up to 739.4 S m-1) and excellent specific EMI shielding efficiency (up to 2647 dB cm2 g-1) at an ultrathin thickness (minimum thickness 47 μm). The nacre-inspired strategy in this study offers a promising approach for the design and preparation of the strong integrated and flexible MXene/CNF composite paper, which may be applied in various fields such as flexible wearable devices, weapon equipment, and robot joints.

Ultralong hydroxyapatite microtubes: solvothermal synthesis and application in drug loading and sustained drug release

In this work, monodisperse single-crystalline ultralong hydroxyapatite (HAP) microtubes have been successfully synthesized using a reaction system containing CaCl2, NaOH, (NaPO3)6, oleic acid, water and ethanol by a solvothermal method. The formation mechanism of HAP microtubes and the effects of solvothermal temperature, pH value, Ca/P molar ratio, and volume ratio of solvents on the product have been investigated. Due to the unique tubular structure, the as-prepared ultralong HAP microtubes exhibit high biocompatibility and superior properties in drug loading and sustained drug release. The as-prepared HAP microtubes are promising for applications in various biomedical fields such as drug/gene delivery and bone defect repair.

A novel composite scaffold comprising ultralong hydroxyapatite microtubes and chitosan: preparation and application in drug delivery

In this work, a novel ultralong hydroxyapatite microtube (HMT)-chitosan (CHS) composite scaffold has been successfully prepared. The mechanical properties of the HMT-CHS composite scaffold is greatly improved compared with the CHS-hydroxyapatite nanorod scaffold and the pure chitosan scaffold. By using gentamicin sulfate (GS) as the model drug, the GS-loaded HMT-CHS composite scaffold has a high drug loading capacity, sustained drug release behavior and high antibacterial activity. The as-prepared HMT-CHS composite scaffold has promising applications in various fields such as drug delivery and bone defect repair.

Biocompatible, Ultralight, Strong Hydroxyapatite Networks Based on Hydroxyapatite Microtubes with Excellent Permeability and Ultralow Thermal Conductivity

In the past decade, ultralight materials such as aerogels have become one of the hottest research topics owing to their unique properties. However, most reported ultralight materials are bioinert. In this work, by using biocompatible, monodisperse, single-crystalline hydroxyapatite (HAP) microtubes as the building blocks, ultralight, strong, highly porous, three-dimensional (3-D) HAP networks have been successfully fabricated through a facile freeze-drying method and subsequent sintering at 1300 °C for 2 h. The as-prepared ultralight, strong, highly porous 3-D HAP microtube networks exhibit superior properties, such as ultrahigh porosity (89% to 96%), low density (94.1 to 347.1 mg/cm3), high compressive strength that can withstand more than 6400 times of their own weight without any fracture and is higher than aerogels with similar densities, and ultralow thermal conductivity (0.05 W/mK). Owing to their high porosity, ultralight, and good mechanical properties and high biocompatibility, the HAP microtube networks reported herein are promising for applications in various fields.

Dopamine-modified highly porous hydroxyapatite microtube networks with efficient near-infrared photothermal effect, enhanced protein adsorption and mineralization performance.

In the last decade, the porous hydroxyapatite (HAP) scaffold has been investigated for the application in tissue engineering owing to its good bioactivity and high biocompatibility. In this work, the dopamine-modified highly porous hydroxyapatite microtube three-dimensional (3-D) networks with efficient near-infrared photothermal effect, enhanced protein adsorption and mineralization performance have been prepared through a facile method. The dopamine-modified highly porous HAP networks exhibit ultrahigh porosity (90.6%), uniform pore distribution, interconnected pore structure and outstanding mechanical properties. After being modified with dopamine, the protein adsorption amount, cell attachment performance, and mineralization ability of the dopamine-modified highly porous HAP network can be greatly improved. In addition, the as-prepared dopamine-modified highly porous HAP networks exhibit good biocompatibility, excellent near-infrared photothermal effect, and good mechanical properties. The experimental results indicate that the dopamine-modified highly porous HAP networks are promising for various applications.