Biodegradable Hydrogel Beads Combined with Calcium Phosphate Bone Cement for Bone Repair: In Vitro and In Vivo Characterization.

This study evaluated the in vitro characterizations of biodegradable hydrogel beads with calcium phosphate bone cement (CPC). Commercial fast-setting CPC and hydrogel beads were compared with 25%-volume hydrogel in CPC (C/0.25) in vivo. The histological behaviors and absorption rates of CPC only, hydrogel beads, and hydrogel/CPC composite were measured and compared at 4, 8, and 12 weeks. The results indicated that the C/0.25 composite can be molded and does not disintegrate when immersed in the solution, but this delays the phase transition of the CPC into the product in the early reaction process. The osteoprogenitor D1 cell affinity of the C/0.25 composite was equally competitive with that of the CPC-only. Adding hydrogel beads to CPC did not inhibit cell proliferation as well as differentiation of osteoprogenitor cells. In vivo histological evaluations did not indicate any significant difference in the CPC-only, hydrogel-only, and C/0.25 composite after 4 weeks of implantation; however, significantly less residue was observed in the C/0.25 composite relative to the CPC-only after 8 weeks. After 12 weeks of hydrogel beads implantation, the hydrogel degraded substantially, creating vacancies that were subsequently occupied by a large amount of soft tissue. New bone was formed in large quantities in the C/0.25; therefore, the C/0.25 composite is a promising option for a wide range of dental, craniofacial, and orthopedic applications.

In Vitro Evaluation of Calcium Phosphate Bone Cement Composite Hydrogel Beads of Cross-Linked Gelatin-Alginate with Gentamicin-Impregnated Porous Scaffold.

Calcium phosphate bone cement (CPC) is in the form of a paste, and its special advantage is that it can repair small and complex bone defects. In the case of open wounds, tissue debridement is necessary before tissue repair and the subsequent control of wound infection; therefore, CPC composite hydrogel beads containing antibiotics provide an excellent option to fill bone defects and deliver antibiotics locally for a long period. In this study, CPC was composited with the millimeter-sized spherical beads of cross-linked gelatin-alginate hydrogels at the different ratios of 0 (control), 12.5, 25, and 50 vol.%. The hydrogel was impregnated with gentamicin and characterized before compositing with CPC. The physicochemical properties, gentamicin release, antibacterial activity, biocompatibility, and mineralization of the CPC/hydrogel composites were characterized. The compressive strength of the CPC/hydrogel composites gradually decreased as the hydrogel content increased, and the compressive strength of composites containing gentamicin had the largest decrease. The working time and setting time of each group can be adjusted to 8 and 16 min, respectively, using a hardening solution to make the composite suitable for clinical use. The release of gentamicin before the hydrogel beads was composited with CPC varied greatly with immersion time. However, a stable controlled release effect was obtained in the CPC/gentamicin-impregnated hydrogel composite. The 50 vol.% hydrogel/CPC composite had the best antibacterial effect and no cytotoxicity but had reduced cell mineralization. Therefore, the optimal hydrogel beads content can be 25 vol.% to obtain a CPC/gentamicin-impregnated hydrogel composite with adequate strength, antibacterial activity, and bio-reactivity. This CPC/hydrogel containing gentamicin is expected to be used in clinical surgery in the future to accelerate bone regeneration and prevent prosthesis infection after surgery.

Effects of Gamma Radiation on the Sterility Assurance, Antibacterial Ability, and Biocompatibility of Impregnated Hydrogel Macrosphere Protein and Drug Release.

Devices and medicines used in the medical field must be sterile. Gamma (γ)-irradiation is commonly used for sterilization because its high rate of penetration ensures uniform sterilization. To confirm that hydrogel macrosphere carriers inherit excellent liquid absorption with no cytotoxicity after γ-irradiation sterilization, investigating whether the physiochemical properties of hydrogel macrospheres differ before and after sterilization is essential. The present study evaluated the influence of the recommended 25-kGy γ-irradiation dose on the physicochemical characteristics and in vitro release of bovine serum albumin and vancomycin (an antibiotic medication) from alginate/gelatin with a w/w ratio of 1/4 crosslinking gel macrospheres. Gel macrosphere properties before and after sterilization were compared according to optical and scanning electron microscopy, infrared spectroscopy analysis, the amino residual crosslinking index, water absorption, degradation, sterility assurance, in vitro drug release, antibacterial ability, and cytotoxicity. The crosslinking index was almost unchanged; however, the γ-irradiation caused in situ hydrogel debonding and recrosslinking, which led to a decrease in the water absorption and increase in the degradation rate of the macrospheres after immersion. The release of gel macrospheres carrying vancomycin did not significantly affect antibacterial ability or biocompatibility after γ-irradiation. Accordingly, we conclude that γ-irradiation is suitable for macrospherical formulation.

A boronic acid modified binary matrix consisting of boron nitride and α-cyano-4-hydroxycinnamic acid for determination of cis-diols by MALDI-TOF MS.

A MALDI-TOF mass spectrometric method is described for the determination of small molecule compounds with cis-diol. It is based on the use of a binary matrix consisting of boron nitride (BN) and α-cyano-4-hydroxycinnamic acid that was modified with the derivatization reagent of (3-(acridin-9-ylamino)phenyl)boronic acid which can recognize cis-diols. The binary matrix is used for desorption/ionization (DI) in the positive ion mode. The mechanism leading to DI enhancement was investigated. The results imply that BN is beneficial for the DI because it induces an enhancement in the positive ion mode. The boronic acid-functionalized binary matrix was successfully applied to capture the glucose, shikimic acid and quinic acid. The method was applied to the determination of 3-chloro-1,2-propanediol in plant oil. Graphical abstract Schematic representation of a method for detecting the cis-diol compounds on matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) using the binary matrix of boron nitride (BN)/α-cyano-4-hydroxycinnamic acid (CHCA) that was modified with (3-(acridin-9-ylamino)phenyl) boronic acid (AYPBA).

Synthesis of tellurium nanosheet for use in matrix assisted laser desorption/ionization time-of-flight mass spectrometry of small molecules.

Two-dimensional tellurium nanosheets were prepared by a hydrothermal method and characterized by scanning electron microscopy, powder X-ray diffractometry, and UV-vis spectroscopy. The nanosheets were explored as a novel matrix for desorption/ionization of small molecules including nucleobases, fatty acids and amino acids by matrix assisted laser desorption/ionization time-of-flight mass spectrometry. The results show that the tellurium nanosheets have good UV light absorption, cause low matrix ion interference in the low-molecule-mass region, and have high desorption/ionization efficiency in the negative ion mode. Hence, they are a viable matrix for negative ion desorption/ionization in MALDI-TOF MS of small molecules. In order to investigate the desorption/ionization mechanisms, benzylpyridinium salt and bisphenol A were adopted as probes. The results show that both of the electronic transitions mechanism and laser-induced thermal mechanism play important roles in desorption/ionization process. Graphical abstract Two-dimensional tellurium (Te) nanosheet was synthesized by a hydrothermal method and explored as a novel matrix for desorption/ionization of small molecules by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

Interaction of progenitor bone cells with different surface modifications of titanium implant.

Changes in the physical and chemical properties of Ti surfaces can be attributed to cell performance, which improves surface biocompatibility. The cell proliferation, mineralization ability, and gene expression of progenitor bone cells (D1 cell) were compared on five different Ti surfaces, namely, mechanical grinding (M), electrochemical modification through potentiostatic anodization (ECH), sandblasting and acid etching (SLA), sandblasting, hydrogen peroxide treatment, and heating (SAOH), and sandblasting, alkali heating, and etching (SMART). SAOH treatment produced the most hydrophilic surface, whereas SLA produced the most hydrophobic surface. Cell activity indicated that SLA and SMART produced significantly rougher surfaces and promoted D1 cell attachment within 1 day of culturing, whereas SAOH treatment produced moderate roughness (Ra=1.26µm) and accelerated the D1 cell proliferation up to 7 days after culturing. The ECH surface significantly promoted alkaline phosphatase (ALP) expression and osteocalcin (OCN) secretion in the D1 cells compared with the other surface groups. The ECH and SMART-treated Ti surfaces resulted in maximum ALP and OCN expressions during the D1 cell culture. SLA, SAOH, and SMART substrate surfaces were rougher and exhibited better cell metabolic responses during the early stage of cell attachment, proliferation, and morphologic expressions within 1 day of D1 cell culture. The D1 cells cultured on the ECH and SMART substrates exhibited higher differentiation, and higher ALP and OCN expressions after 10 days of culture. Thus, the ECH and SMART treatments promote better ability of cell mineralization in vitro, which demonstrate their great potential for clinical use.