A novel multifunctional NCQDs-based injectable self-crosslinking and in situ forming hydrogel as an innovative stimuli responsive smart drug delivery system for cancer therapy.

In this work, we offer an easy approach to develop a novel injectable, pH sensitive and in situ smart drug delivery system for use in cancer treatments. The developed hydrogels containing nitrogen doped carbon quantum dots (NCQD), doxorubicin (Dox) and hydroxyapatite (HA) were obtained by in situ self-crosslinking. Characterization of the synthesized nanomaterials, interactions between NCQD/Dox/HA hydrogel structure were carried out by TEM, FESEM, EDS, FTIR, XPS, XRD, Zeta potential, DLS, UV-Vis, SEM, gelation time, injectability and DIST measurements. In addition, antibacterial evaluation which was performed against Staphylococcus aureus realized that HA compound significantly increased the antibacterial activity of the hybrid hydrogel. The anticancer drug release to the tumor cell microenvironment with a pH of 5.5 was found to be higher compared to the release in the normal physiological range of pH 6.5 and 7.4. MTT and live/dead assays were also performed using L929 fibroblastic cell lines to investigate the cytotoxic behavior of NCQDs, and NCQDs/Dox/HA hydrogels. Furthermore, the NCQDs/Dox/HA hydrogel could transport Dox within a MCF-7 cancerous cell at specifically acidic pH. Additionally, imaging of cell line was observed using NCQDs and their use in imaging applications and multicolor features in the living cell system were evaluated. The overall study showed that in situ formed NCQDs/Dox/HA hydrogel represented a novel and multifunctional smart injectable controlled-release drug delivery system with great potential, which may be considered as an attractive minimal invasive smart material for future intelligent delivery of chemotherapeutic drug and disease therapy applications.

Biomimetic synthesis of Ag, Zn or Co doped HA and coating of Ag, Zn or Co doped HA/fMWCNT composite on functionalized Ti.

In this study a novel composite containing fMWCNT and Ag, Zn or Co doped hydroxyapatite (HA) and undoped HA successfully synthesized using biomimetic process and coated on the chemically silane functionalized Ti via facile surface functionalization and deposition approach through the covalent immobilization. In this approach, the properties of Ti pretreated with NaOH and APTES were examined before the composite coating. Functional groups with oxygen were created on the MWCNT surface by acidic treatment. The synthesized powders were characterized using SEM, XRD, EDS, TGA, FTIR, Raman. Surface energies were decreased from 46.03 mN/m (Ti) to 43,79 mN/m (Ti-/fMWCNT/Ag, Zn or Co doped HA). The contact angles of APTES, fMWCNT and undoped or doped HA containing Ti surfaces increased from 40.03 ±â€¯1.2 to 49.05 ±â€¯1.6°. The bond strengths between the coatings and Ti substrates were measured using an adhesive strength test which indicates that the crosslinking process increased the adhesion strength (from 14.6 ±â€¯0.9 to 19.8 ±â€¯1.2 MPa). The results indicated that the Ag+, Zn2+ or Co2+ added in prepared SBF medium have been located in the HA lattice structure at rate of 1.06, 1.86 and 1.78 at.%, respectively. The biocompatibility of the synthesized composites was evaluated using MTT assays in vitro and no negative effect was observed on cell viability. This work shows that the fMWCNT/Ag, Zn or Co doped HA coating promise for the potential implementation in biomaterial coating fields.

3D porous collagen/functionalized multiwalled carbon nanotube/chitosan/hydroxyapatite composite scaffolds for bone tissue engineering.

In this study, we describe new collagen/functionalized multiwalled carbon nanotube/chitosan/hydroxyapatite (Col/f-MWCNT/CS/HA) composite scaffolds which were fabricated by freezing (-40 °C at 0.9 °C/min) and lyophilization (48 h, 0 °C and 200 mtorr). The compressive stresses (from 523 to 1112 kPa), swelling (from 513.9 ±â€¯27 to 481.05 ±â€¯25%), porosity (from 98 ±â€¯0.15 to 95.7 ±â€¯0.1%), contact angle (from 87.8 to 76.7°) properties examined before and after biomineralization for comparison 3D porous Col, CS, Col/f-MWCNT and Col/f-MWCNT/CS scaffolds. Biomineralization was performed by biomimetic method in concentrated SBF (10 × SBF, at 37 °C and 6.5 pH). XRD, SEM, EDS, FTIR, TGA, Optical microscopy and BET results showed that compared to Col, CS and Col/f-MWCNT scaffolds, Col/f-MWCNT/CS scaffolds had higher in vitro bioactivity, large surface area (11.746 m2/g) and a good pore volume (0.026 cc/g), interconnected porous microstructure (with 20-350 µm pore size) and incorporates the advantageous properties of both Col, f-MWCNT, CS and HA. Finally, the methyl thiazolyl tetrazolium (MTT) assay was performed to evaluate scaffolds cytotoxicity which showed that Col/f-MWCNT/CS scaffolds have the best biocompatibility.

Microwave-assisted biomimetic synthesis of hydroxyapatite using different sources of calcium.

In this study, some properties of biomimetic synthesized hydroxyapatite by using different sources of calcium were investigated. Biomimetic synthesis of hydroxyapatite was carried out in microwave oven using 1.5 simulated body fluid (SBF) solution having different calcium sources with 800W power for 15min. As phosphorus source di-ammonium hydrogen phosphate ((NH4)2HPO4) while for each sample as a calcium sources calcium chloride (CaCl2), calcium nitrate tetra hydrate (Ca(NO3)2·4H2O) and calcium hydroxide (Ca(OH)2) were utilized, respectively. For comparison, precipitation process was also performed in only 1.5 SBF solution without calcium and phosphorus sources. The presence of phases in synthesized hydroxyapatite was confirmed by XRD. The crystallinity and crystalline size of the phases in as synthesized powders were also calculated by using XRD data. It was found that the unique phase is hydroxyapatite (HAp, Ca5(PO4)3(OH)) by using the calcium nitrate tetra hydrate and calcium hydroxide sources, while the dominant phases are tri-calcium phosphates (TCP) and HAp for CaCl2 source and 1.5SBF which does not contain any additional Ca source. SEM studies revealed that nano-hexagonal rods and nano-spherical hydroxyapatites could be synthesized by using this process. Energy-dispersive X-ray spectroscopy (EDS) analysis revealed that the Ca/P ratio near to be as 1.5 which is the value for HAp in bone. Raman and Fourier transform-infrared spectroscopy (FT-IR) results combined with the X-ray diffraction (XRD) indicates that dominantly the present of single phase is HAp. The crystal size and fraction crystallinity of as synthesized HAp powders were changed between 29.5 and 45.4nm and 0.53-2.37, respectively. Results showed that microwave assisted biomimetic synthesis is a promising method for obtaining HAp powders in shorter process time.