Improvement of Drug-Loading Properties of Hydroxyapatite Particles Using Triethylamine as a Capping Agent: A Novel Approach

Green synthesis of nanohydroxyapatite with Elaeagnus angustifolia L. extract as a metronidazole nanocarrier for in vitro pulpitis model treatment

The aim of this study is to introduce a dental capping agent for the treatment of pulp inflammation (pulpitis). Nanohydroxyapatite with Elaeagnus angustifolia L. extract (nHAEA) loaded with metronidazole (nHAEA@MTZ) was synthesized and evaluated using a lipopolysaccharide (LPS) in vitro model of pulpitis. nHAEA was synthesized through sol-gel method and analyzed using Scanning Electron Microscopy, Transmission Electron Microscopy, and Brunauer Emmett Teller. Inflammation in human dental pulp stem cells (HDPSCs) induced by LPS. A scratch test assessed cell migration, RT PCR measured cytokines levels, and Alizarin red staining quantified odontogenesis. The nHAEA nanorods were 17-23 nm wide and 93-146 nm length, with an average pore diameter of 27/312 nm, and a surface area of 210.89 m2/g. MTZ loading content with controlled release, suggesting suitability for therapeutic applications. nHAEA@MTZ did not affect the odontogenic abilities of HDPSCs more than nHAEA. However, it was observed that nHAEA@MTZ demonstrated a more pronounced anti-inflammatory effect. HDPSCs treated with nanoparticles exhibited improved migration compared to other groups. These findings demonstrated that nHAEA@MTZ could be an effective material for pulp capping and may be more effective than nHAEA in reducing inflammation and activating HDPSCs to enhance pulp repair after pulp damage.

Synthesis and evaluation of nanosystem containing chondroitinase ABCI based on hydroxyapatite

The bacterial enzyme chondroitinase ABCI (chABCI), which has been isolated from Proteus Vulgaris, is crucial in the treatment of spinal cord injuries. However, due to its short lifespan, the maintenance and clinical application of this enzyme are very constrained. In this study, the immobilization of this enzyme on hydroxyapatite has been carried out and assessed with the aim of enhancing the characteristics and efficiency of chABCI. Hydroxyapatite particles (HAPs) are a potential candidate for drug-delivery carriers because of their excellent biocompatibility, shape controllability, and high adsorption. The use of the nanometer scale allows efficient access to the enzyme's substrate. It demonstrates important biological application capabilities in this way. Field emission gun-scanning electron microscopy (FEG-SEM), X-ray diffraction (XRD), infrared spectroscopy (FT-IR), in vitro release study, and cytotoxicity test were used to characterize the drug nanosystem's properties. According to the findings, electrostatic bindings was formed between charged groups of the enzyme and hydroxyapatite nanoparticles. The results also demonstrated that immobilized chABCI on hydroxyapatite has beneficial properties, such as more manageable drug release, minimal toxicity and side effects, and a high potential to enhance the efficacy of drug delivery and decrease the need for repeated injections.

Bioleaching and immobilizing of copper and zinc using endophytes coupled with biochar-hydroxyapatite: Bipolar remediation for heavy metals contaminated mining soils

Copper and zinc are toxic heavy metals in soils that require development of feasible strategies for remediation of contaminated soils around the mine areas. In this study, the processing conditions and mechanisms of immobilization and bioleaching for remediation of highly contaminated soils with heavy metals are investigated. Soil remediation is carried out using a bioleaching-immobilization bipolar method. The results show that LSE03 bacteria provide efficient leaching result and immobilization on Cu²⁺ and Zn²⁺. Among the bacterial metabolites, cis, cis-muconic acid and isovaleric acid play major roles in the bioleaching process. The bacterial extracellular polymeric substances are rich in a variety of organic acids that show a significant decrease in content after the adsorption process, indicating that all of these substances are involved in the binding of heavy metals. Characterization of the endophytes and immobilizing agents with FTIR, TEM-mapping, and XPS techniques reveal the ability of both bacteria and composites to adsorb Cu-Zn as well as the main functional groups of -OH, -COOH, -PO₄^3-, and -NH. According to the heavy metals species analyses, competitive adsorption experiments, and bioleaching desorption experiments, it is planned to carry out the bipolar remediation of contaminated soil through immobilization followed by bioleaching process. After bipolar remediation processing, 97.923% and 96.387% of available Cu and Zn are respectively removed. Soils fertility significantly increases in all cases. Our study provides a green, practical, and environmentally friendly treatment method for soils contaminated with high concentrations of heavy metals.

Light-enhanced transparent hydrogel for uric acid and glucose detection by four different analytical platforms

The lack of solid-phase media limits the portability of colorimetric sensing platforms. In this study, a series of transparent polyvinyl alcohol (PVA) hydrogels encapsulated antimony tin oxide nanoparticles (ATO NPs) and 3,3',5,5'-tetramethylbenzidine (TMB) were developed as the solid-phase sensing media for glucose and uric acid. Under the conditions of H₂O₂ and UV light, the hydrogel presented a multicatalytic ability (photo Fenton-like and peroxidase-like activities), which accelerated the oxidation of TMB, turning the hydrogel from colorless to blue and finally enhancing the detection signal. The plasticity of the hydrogel allowed it to be designed into various shapes (membrane, microsphere etc.) to adapt multiple detection platforms (a liquid/solid-phase UV spectrophotometer, a NanoPhotometer, and smartphone spectroscopy). The hydrogel sensing media exhibited excellent tunability and enhanced the photocatalytic ability. The proposed material was successfully applied to detect glucose and uric acids in real samples by four detection platforms to evaluate its practicability.

Fabrication of Porous Crystalline PLGA-PEG Induced by Swelling during the Recrystallization Annealing Process

Poly(lactide-co-glycolide) (PLGA) has been widely used as a scaffold material for tissue engineering owing to its biocompatibility, biodegradability, and biosafety. However, lactic acid (LA) produced during PLGA degradation is prone to inflammation, which is a shortcoming that must be avoided. To this end, crystalline PLGA-PEG was synthesized here for the first time. To make the crystalline PLGA-PEG more suitable for tissue engineering, porous crystalline PLGA-PEG was prepared via the swelling behavior during recrystallization annealing. The structure and properties of the porous crystalline PLGA-PEG were confirmed by SEM, POM, and XRD. Furthermore, the swelling behavior of different PEG molecular weights was studied, and the cell viability test and alkaline phosphatase activity test showed that PLGA-PEG has good biocompatibility. Such a porous crystalline PLGA-PEG will make PLGA have a broader application prospect in bone repair.

Glucose-Targeted Hydroxyapatite/Indocyanine Green Hybrid Nanoparticles for Collaborative Tumor Therapy

Nanoscale hydroxyapatite (nHA) is considered as a promising drug carrier or therapeutic agent against malignant tumors. But the strong agglomeration tendency and lack of active groups seriously hamper their usage in vivo. To address these issues, we fabricated an organic-inorganic hybrid nanosystem composed of poly(acrylic acid) (PAA), nHA, and indocyanine green (ICG), and further modified with glucose to give a targeting nanosystem (GA@HAP/ICG-NPs). These hybrid nanoparticles (∼90 nm) showed excellent storage and physiological stability assisted by PAA and had a sustained drug release in an acidic tumor environment. In vitro cell experiments confirmed that glucose-attached particles significantly promoted cellular uptake and increased intracellular ICG and Ca2+ concentrations by glucose transporter 1 (GLUT1)-mediated endocytosis. Subsequently, the excessive Ca2+ induced cell or organelle damage and ICG triggered photothermal and photodynamic effects (PTT/PDT) under laser irradiation, resulting in enhanced cell toxicity and apoptosis. In vivo tests revealed that the hybrid nanosystem possessed good hemocompatibility and biosafety, facilitating in vivo circulation and usage. NIR imaging further showed that tumor tissues had more drug accumulation, resulting in the highest tumor growth inhibition (87.89%). Overall, the glucose-targeted hybrid nanosystem was an effective platform for collaborative therapy and expected to be further used in clinical trials.

Photoluminescent Properties of Hydroxyapatite and Hydroxyapatite/Multi-Walled Carbon Nanotube Composites

Hydroxyapatite (HAp) and hydroxyapatite/multi-walled carbon nanotube (MWCNT) composites were obtained by the co-precipitation method, followed by ultrasound-assisted and microwave radiation and thermal treatment at 250 °C. X-ray diffraction (XRD) confirmed the presence of a hexagonal phase in all the samples, while Fourier-transform infrared (FTIR) spectroscopy elucidated the interaction between HAp and MWCNTs. The photoluminescent technique revealed that HAp and the composite with non-functionalized MWCNTs present a blue luminescence, while the composite with functionalized MWCNTs, under UV-vis radiation shows an intense white emission. These findings allowed presentation of a proposal for the use of HAp and HAp with functionalized MWCNTs as potential materials for optoelectronic and medical applications.