C60 fullerene loaded hydroxyapatite-chitosan beads as a promising system for prolonged drug release

Towards sustainable microplastic cleanup: Al/Fe ionotropic chitosan hydrogels for efficient PET removal

Chitosan (CHI) was modified with iron and aluminum salts to create ionotropic beads, Fe-CHI and Al-CHI, for the removal of polyethylene terephthalate microplastics (PET-MP) from water. Infrared spectroscopy revealed reduced hydrogen bonding associated with N-H vibration of CHI (3500-3100 cm-1) due to the interaction with the metal ions, and absorption peaks between 500 and 916 cm⁻1 predominantly due to metal-oxygen stretching vibrations. The swelling behavior of the beads increased with temperature but decreased as pH and metal doping concentration increased. Conductivity and PET-MP removal efficiency improved with higher metal ion concentrations, with Al-CHI exhibiting greater swelling and conductivity compared to Fe-CHI. The highest efficiency for MP remediation was recorded at low pH levels. MP adsorption decreased with rising temperatures and varied with pH changes due to protonation and deprotonation reactions of CHI, along with the various cationic and anionic species formed by the metals. At pH 7, MP removal by Fe-CHI beads declined as the doping concentration increased, attributed to specific Fe species that emerged at this pH. The zeta potential measurements showed that both the beads and the MP were in an unstable range at low pH but shifted towards stability at higher pH levels. Re-adsorption efficiencies exceeded 70% for both low and high-doped Fe-CHI and Al-CHI beads when tested with ~ 40 MP/mL of MP suspension over three different cycles. Overall, the use of ionotropic CHI beads offers a promising, eco-friendly method for effectively reducing PET-MPs in water.

3D chitosan/hydroxyapatite scaffolds containing mesoporous SiO2-HA particles: A new step to healing bone defects

Biocompatible scaffolds with high mechanical strengths that contain biodegradable components could boost bone regeneration compared with nondegradable bone repair materials. In this study, porous chitosan (CS)/hydroxyapatite (HA) scaffolds containing mesoporous SiO2-HA particles were fabricated through the freeze-drying process. According to field emission scanning electron microscopy (FESEM) results, combining mesoporous SiO2-HA particles in CS/HA scaffolds led to a uniform porous structure. It decreased pore sizes from 320 ± 1.1 μm to 145 ± 1.4 μm. Moreover, the compressive strength value of this scaffold was 25 ± 1.2 MPa. The in-vitro approaches exhibited good sarcoma osteogenic cell line (SAOS-2) adhesion, spreading, and proliferation, indicating that the scaffolds provided a suitable environment for cell cultivation. Also, in-vivo analyses in implanted defect sites of rats proved that the CS/HA/mesoporous SiO2-HA scaffolds could promote bone regeneration via enhancing osteoconduction and meliorating the expression of osteogenesis gene to 19.31 (about 5-fold higher compared to the control group) by exposing them to the bone-like precursors. Further, this scaffold's new bone formation percentage was equal to 90 % after 21 days post-surgery. Therefore, incorporating mesoporous SiO2-HA particles into CS/HA scaffolds can suggest a new future tissue engineering and regeneration strategy.

Incorporating mesoporous SiO2-HA particles into chitosan/hydroxyapatite scaffolds: A comprehensive evaluation of bioactivity and biocompatibility

In this work, composite scaffolds with various composition ratios of chitosan (CS), hydroxyapatite (HA), and mesoporous SiO2 particles co-synthesized with hydroxyapatite (SiO2-HA) were fabricated via the freeze-drying method for bone tissue engineering applications. Morphological studies showed that adding mesoporous particles resulted in a structure with a more uniformly porous geometry, subsequently leading to reduced biodegradation rates and water absorption in the scaffolds. The bioactivity results showed the introduction of mesoporous particles notably enhanced the coverage of the scaffold surface with apatite films. Moreover, biocompatibility assessments using sarcoma osteogenic cell line (SAOS-2) highlighted mesoporous particles' positive impact on cell adhesion and growth. The fluorescence images showed spindle-shaped cells with a greater number and normal cell nuclei for the scaffolds containing mesoporous SiO2-HA particles. The MTT cytotoxicity results indicated that the scaffolds containing mesoporous particles showed approximately 25 % higher cell survival more than single chitosan-based ones. What is more, the mesoporous-containing scaffolds occurred to have the best alkaline phosphatase test (ALP) activity among all scaffolds. It is important to add that CS/HA/mesoporous SiO2-HA scaffolds including SAOS-2 cells showed no sign of either early or late apoptosis. These findings affirm the potential of CS/HA/mesoporous SiO2-HA scaffolds as promising implants for bone tissue engineering.

Effect of zinc oxide micro- and nanoparticles on cytotoxicity, antimicrobial activity and mechanical properties of apatite-polymer osteoplastic material

This work is devoted to the comparison of the physical and biological properties of synthesized osteoplastic composites with an experimentally determined content (375 μg/g) of the micro (ZnOMPs) and nano (ZnONPs) particles, immobilized in Hydroxyapatite-Alginate-Chitosan matrix (HA-Alg-CS). ZnONPs show pronounced antimicrobial activity against E.coli ATCC 25922 and S. aureus ATCC 25923, while ZnOMPs only in the CS presence. Composites containing ZnONPs/MPs do not have a toxic effect on bone-forming cells - osteoblasts, preserving their ability to biomineralization. ZnOMPs and ZnONPs to varying degrees, but significantly affect composites' swelling, porosity, shape stability, and prolong vitamin D3 release for 120h, compared to Control. Composites do not demonstrate unwanted "burst release." ZnONPs/MPs increase Youngs' modulus of the HA-Alg matrix, namely 348 → 419 MPa (ZnOMPs), 348 → 646 MPa (ZnONPs), and weaken the plastic (irreversible) deformations. The compressive strength of HA-Alg and HA-Alg/CS matrixes containing ZnONPs (178 MPa and 251 MPa, respectively) is in the range of values for native cortical bone (170-193 MPa). Biocompatibility and lack of toxic effect give both composites a perspective for osteoplastic application, but composites doped with ZnONPs are more attractive.

A potential hybrid nanocomposite of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and fullerene for bone tissue regeneration and sustained drug release against bone infections

Developing a multifunctional biomaterial for bone filling and local antibiotic therapy is a complex challenge for bone tissue engineering. Hybrid nanocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) with nanohydroxyapatite (nHA), fullerene (C60), and vancomycin (VC) were produced by injection. Fullerene was successfully impregnated with VC, as seen in FTIR. The crystallinity degree of PHBHV was slightly reduced in the presence of C60 and VC (64.3 versus 60.8 %), due to the plasticizing effect of these particles. It also resulted in a decrease in the glass transition temperature (Tg), observed by differential scanning calorimetry (DSC). Dense PHBHV/nHA/C60/VC had a flexural elastic modulus 29 % higher than PHBHV, as a result of the good interface between PHBHV, C60, and nHA - particles of high elastic modulus. Dense disks released 25.03 ± 4.27 % of VC for 14 days, which demonstrated its potential to be an alternative treatment to bone infections. Porous scaffolds of PHBHV/nHA/C60/VC were 3D printed with a porosity of 50 % and porous size of 467 ± 70 μm, and had compression elastic modulus of 0.022 GPa, being a promising material to trabecular bone replacement. The plasticizing effect of C60 improved the printability of the material. The hybrid nanocomposite was non-cytotoxic and showed good ability in adhering macrophage cells.

Self-Assembled Supramolecular Micelles Based on Multiple Hydrogen Bonding Motifs for the Encapsulation and Release of Fullerene

Living creatures involve several defense mechanisms, such as protecting enzymes to protect organs and cells from the invasion of free radicals. Developing antioxidant molecules and delivery systems to working with enzymes is vital. In this study, a supramolecular polymer PNI-U-DPy was used to encapsulate C₆₀, a well-known antioxidant that is hard to dissolve or disperse in the aqueous media. PNI-U-DPy exhibits characteristics similar to PNIPAM but could form micelles even when the environment temperature is lower than its LCST. The U-DPy moieties could utilize their strong complementary hydrogen bonding-interaction to create a physically crosslinked network within PNIPAM micelles, thus adjusting its LCST to a value near the physiological temperature. Morphological studies suggested that C₆₀ could be effectively loaded into PNI-U-DPy micelles with a high loading capacity (29.12%), and the resulting complex PNI-C₆₀ is stable and remains temperature responsive. A series of measurements under variable temperatures was carried out and showed that a controlled release process proceeded. Furthermore, PNI-C₆₀ exhibits hydroxyl radicals scavenging abilities at a low dosage and could even be adjusted by temperature. It can be admitted that the micelle system can be a valuable alternative for radical scavengers and may be delivered to the desired position with good dispersibility and thermo-responsivity. It is beneficial to the search progress of scientists for drug delivery systems for chemotherapeutic treatments and biomedical applications.

Incorporation of Fluorescent Fluorinated Methacrylate Nano-Sized Particles into Chitosan Matrix Formed as a Membranes or Beads

Fluorescent particles are of particular interest as probes and active agents for biomedical, pharmaceutical, and food applications. Here, we present two strategies for incorporation of core-shell acrylic fluorescent nanoparticles (NPs) with Rhodamine B (RhB) as a dye into a chitosan (CS) matrix. We selected two variants of NPsRhB immobilisation in a CS membrane and biopolymeric CS beads. Modification of the method for production of the biopolymer cover/transporter of nanoparticles allowed two series of hydrogels loaded with nanoparticles to be obtained with a similar concentration of the aqueous solution of the nanoparticles. Microscopic analysis showed that the NPs were nonuniformly distributed in millimetre-sized CS beads, as well as membranes, but the fluorescence signal was strong. The composition of CS layers loaded with nanoparticles (CS/NPsRhB) showed water vapour barrier properties, characterised by the contact angle of 71.8°. Finally, we incorporated NPsRhBCS beads into a gelatine matrix to check their stability. The results confirmed good stability of the NPsRhBCS complex system, and no dye leakage was observed from the beads and the membranes. The proposed complex system demonstrated promising potential for further use in bioimaging and, thus, for the development of advanced diagnostic tools.

Fabrication and applications of bioactive chitosan-based organic-inorganic hybrid materials: A review

Organic-inorganic hybrid materials like bone, shells, and teeth can be found in nature, which are usually composed of biomacromolecules and nanoscale inorganic ingredients. Synergy of organic-inorganic components in hybrid materials render them outstanding and versatile performance. Chitosan is commonly used organic materials in bionic hybrid materials since its bioactive properties and could be controllable tailored by various means to meet complex conditions in different applications. Among these fabrication means, hybridization was favored for its convenience and efficiency. This review discusses three kinds of chitosan-based hybrid materials: hybridized with hydroxyapatite, calcium carbonate, and clay respectively, which are the representative of phosphate, carbonate, and hydrous aluminosilicates. Here, we reported the latest developments of the preparation methods, composition, structure and applications of these bioactive hybrid materials, especially in the biomedical field. Despite the great progress was made in bioactive organic-inorganic hybrid materials based on chitosan, some challenges and specific directions are still proposed for future development in this review.

N Basicity of Substituted Fullero[60]/[70]pyrrolidines According to DFT/TD-DFT Calculations and Chemical Thermodynamics

The basicity thermodynamic parameters of pyridyl/imidazole-substituted fullero[60]/[70]pyrrolidines with respect to N heteroatoms in dichloromethane, which are necessary both to deepen insight into aromaticity "neque levia" and to create supramolecular chemical structures for application, are obtained and discussed in this work. Because of the presence of a chromophore in the molecules, the acid-base reactions of three C₆₀ derivatives functionalized in different ways and one C₇₀ derivative are studied using spectrophotometric titration with trifluoroacetic acid. The dependence of the pK values determined using the data on Hammett's acidity functions, H₀, for a binary nonaqueous solvent on the molecule's chemical structure is shown. Density functional theory (DFT) and time-dependent DFT (TD-DFT) at the B3LYP/6-311G(d,p) level were used for the optimization of the fullerene derivative structures and modeling of their UV-vis spectra. The pK_BH⁺ values of substituted fullero[60]/[70]pyrrolidines are predicted by quantum-chemical calculations.

Hydroxyapatite-biopolymers-ZnO composite with sustained Ceftriaxone release as a drainage system for treatment of purulent cavities

Composite based on nano-sized hydroxyapatite (HA), zinc oxide (ZnO), chitosan (CS), alginate (Alg) with the function of sustained Ceftriaxone (CF) release was created as molecular sorption-aspiration drainage system (SADS), designed for the treatment of purulent cavities of various genesis, including peritonitis. ZnO stabilizes the composite structurally, reducing the swelling by 1.5 and porosity by 1.4 times. The absorption of tryptophan (Trp) by SADS for 72 h from aqueous solution is 80%, while from PBS - 50%. The content of ZnO (15,20%) slows the CF release by 1.6 times on the first day of SADS installation and reduces the likelihood of "burst" drug release. CF release exponent of ZnO-containing composites indicates the non-Fickian diffusion kinetics. 20%ZnO-containing composite is closest to zero-order kinetics. The reduction of the concentration of E. coli microbial cells for 43% in the presence of HA-nZnO-Alg/CS -based CADS and positive therapeutic pathomorphosis were observed in vivo.

Composites Based on Hydroxyapatite and Whey Protein Isolate for Applications in Bone Regeneration

Hydroxyapatite (HAp) is a bioactive ceramic with great potential for the regeneration of the skeletal system. However, its mechanical properties, especially its brittleness, limit its application. Therefore, in order to increase its ability to transmit stresses, it can be combined with a polymer phase, which increases its strength without eliminating the important aspect of bioactivity. The presented work focuses on obtaining organic-inorganic hydrogel materials based on whey protein isolate (WPI) reinforced with nano-HAp powder. The proportion of the ceramic phase was in the range of 0-15%. Firstly, a physicochemical analysis of the materials was performed using XRD, FT-IR and SEM. The hydrogel composites were subjected to swelling capacity measurements, potentiometric and conductivity analysis, and in vitro tests in four liquids: distilled water, Ringer's fluid, artificial saliva, and simulated body fluid (SBF). The incubation results demonstrated the successful formation of new layers of apatite as a result of the interaction with the fluids. Additionally, the influence of the materials on the metabolic activity according to ISO 10993-5:2009 was evaluated by identifying direct contact cytotoxicity towards L-929 mouse fibroblasts, which served as a reference. Moreover, the stimulation of monocytes by hydrogels via the induction of nuclear factor (NF)-κB was investigated. The WPI/HAp composite hydrogels presented in this study therefore show great potential for use as novel bone substitutes.

Study of the complexation of structurally modified curcumin with hydroxypropyl beta cyclodextrin and its effect on anticancer activity

This study aims at modifying curcumin to curcumin pyrazole and complexing it with HPβCD employing a simple protocol to improve curcumin's chemical–physical properties and biological activities.