Nurettin Sahiner

Using 2‐Hydroxypropyl beta‐cyclodextrin (2‐HP‐β‐CD), p(HP‐β‐CD) particles were prepared using divinyl sulfone (DVS) as crosslinker in microemulsion system with smooth surfaces with tens of micrometers size range. P(HP‐β‐CD) particles are negatively charged even at low pHs, for example, ζ = −2.5 mV at pH 2 and decreased with increase in solution pHs, for example, ζ = ~ −12.5 mV at pH 12. The prepared p(HP‐β‐CD) particles afforded a loading capacity of 89.5 ± 1.6 μg/mg of vancomycin, a relatively hydrophilic model drug, corresponding to a loading amount of 8.9% ± 0.2% and an encapsulation efficiency of 17.9% ± 0.4%. Also, 69.1 ± 2.4 μg/mg of vancomycin was released in 24 h, corresponds to 76.8% ± 1.9% of the loaded vancomycin amount. Vancomycin release from p(HP‐β‐CD) particles was best described by the first order kinetic model, which showed a high correlation coefficient ( R ² = 0.9904) and low sum of squares due to regression (SSR = 10.44) and Chi square ( χ ² = 0.36) values, indicating a concentration‐dependent mechanisms. Moreover, blood compatibility testing also demonstrated excellent compatibility, with a hemolysis index% (HI%) of 0.8% ± 0.06% and blood clotting index% (BCI%) of 87 ± 3, even at a concentration of 1000 μg/mL. Furthermore, cytotoxicity testing with L929 fibroblast cell further confirmed that the particles were non‐toxic and mitigated drug toxicity at high concentrations yielding approximately 80% ± 2% cell viability after 25 h of incubation.

Background/Objectives: Carbon dots (CDs) are fluorescent carbon-based nanomaterials attracting considerable attention recently because of their high photostability, tunable luminescence characteristics, low toxicity, and versatile surface chemistry. In this study, Hematoxylin (HT), a naturally occurring phenolic aromatic compound used as a histological staining dye, abundant in hydroxyl functional groups, was selected as a sustainable precursor for CD synthesis. The intrinsic fluorescence and favorable carbonization characteristics of HT are also value-added advantages for CDs. Methods: The use of citric acid (CA) during synthesis improves fluorescence behavior, colloidal stability, and biological performance of CDs. HT-based CDs prepared via the bottom-up synthesis method employing the hydrothermal technique as multifunctional fluorescent materials were also evaluated for potential bioimaging and light-activated antimicrobial applications. Results: The obtained HT-based CDs displayed good aqueous dispersion properties. HT CDs had a hydrodynamic diameter of 115 ± 1 nm and showed a fluorescence emission intensity of 5181 a.u. at λ_em = 329 nm when excited at λ_ex = 300 nm. In contrast, HT:CA CDs prepared at a 1:1 HT-CA weight ratio had a hydrodynamic diameter of 310 ± 19 nm and exhibited a significantly higher fluorescence emission intensity, e.g., 31,840 a.u. at λ_em = 332 nm when excited at λ_ex = 300 nm. Antioxidant studies of HT CDs and HT CDs using four different assays revealed that the antioxidant capacity of HT was partially retained and exhibited a concentration-dependent response. Notably, HT:CA CDs demonstrated significantly enhanced antimicrobial performance under UV-A irradiation compared to HT CDs, with bacterial cell viability calculated as 13 ± 4% for HT:CA CDs and 59 ± 2% for HT CDs. Moreover, HT CDs and HT:CA CDs demonstrated significantly enhanced cytocompatibility on the L929 fibroblast cell line, high cell viability up to 200 μg/mL, versus toxic HT molecules even at 100 μg/mL. Conclusions: HT-based CDs, particularly HT:CA CDs, demonstrated favorable fluorescence, antioxidant, antimicrobial, and cytocompatibility properties, supporting their potential application as multifunctional fluorescent materials for bioimaging and light-activated antimicrobial applications.

Graphitic carbon nitrides (g-C₃N₄) are well-known fluorescent nanosheets that are photoactive under the UV–visible light range and could generate reactive oxygen species (ROS) upon appropriate light exposure. Therefore, these materials are generally favored in diagnostic applications for bioimaging and light-activated treatments simultaneously, e.g., theranostic applications in cancer treatments. Here, the natural polymer, hyaluronic acid (HA), was physically crosslinked with trivalent metal ions such as Gd(III) or Fe(III) ions in the presence of boron (B)- or sulfur (S)-doped graphitic carbon nitride (g-C₃N₄) nanosheets to attain spherical light-sensitive g-C₃N₄@HA-M(III) (M: G(III) or Fe(III) ions) composite microparticles. The g-C₃N₄@HA-M(III) particles were in the 0.5–20 μm size range, which is injectable for possible intravenous administration. No significant toxicity was determined for g-C₃N₄@HA-Gd(III) particles up to 500 μg/mL concentration on L929 fibroblast cells; for example, g-C₃N₄@HA-Fe(III) particles could be used in vivo applications safely up to 100 μg/mL concentration with no toxicity. The g-C₃N₄-based materials exhibited strong fluorescence at λ_ex 380 nm, and S-doped g-C₃N₄@HA-Gd(III) particles provided the highest emission intensity for possible cell imaging applications as a diagnostic tool material. Especially, S-doped g-C₃N₄@HA-M(III) particles delivered photoinduced anticancer activity on SKMEL 30 skin cancer cells after 30 min of UV-A treatment at 6.88 mW/cm² irradiance and 12.38 J/cm fluence via the reactive oxygen species (ROS) production capability. In addition to the targeting ability of HA-M(III) particles, the photoinduced anticancer activity of g-C₃N₄@HA-M(III) particles, e.g., on SKMEL 30 melanoma cells, offer great alternatives to toxic chemo- or radiotherapy. Furthermore, HA-Gd(III)-based particles show the highest signal intensity with better proton relaxation times and the highest proton longitudinal relaxivity. Overall, HA-Gd/Fe(III) particles with heteroatom-doped g-C₃N₄ revealed excellent assets with enhanced MRI capabilities in addition to specific targeted cancer treatments and photoinduced therapy for multifaceted theranostic applications.

Hyaluronic acid (HA) is a high-molecular-weight glycosaminoglycan whose cross-linked hydrogels are widely used as injectable fillers; their controlled degradation is clinically important but, in practice, achievable only enzymatically with hyaluronidase. Here we compared the enzymatic, ultrasonic and photothermal degradation of a single cross-linked HA macromolecular network and characterised the resulting structural, thermal and chromatographic changes. A cross-linked HA hydrogel (Regenyal Idea, 25 mg/mL) was embedded in an ex vivo porcine skin matrix and treated in six groups: untreated control; hyaluronidase; microfocused ultrasound (7 MHz, 3 mm focal depth); and irradiation with 1064 nm Nd:YAG, diode or alexandrite lasers. Degradation was characterised by FT-IR spectroscopy, thermogravimetric analysis (TGA) and high-performance liquid chromatography (HPLC). FT-IR showed retention of the HA backbone with partial loss of the cross-linked network, while TGA revealed treatment-dependent decreases in thermal stability. By HPLC, hyaluronidase released the most soluble HA (58.2 ± 2.9% at day 1; ~88% plateau by day 2). Among the energy-based methods, only the 1064 nm Nd:YAG laser produced comparable degradation (57.3 ± 5.2%), whereas microfocused ultrasound, the diode and the alexandrite lasers released little soluble HA (3.2–5.3%). The wavelength dependence is consistent with a water-mediated photothermal scission of the HA chains. These findings identify long-pulsed 1064 nm irradiation as an effective non-enzymatic route to degrade the cross-linked hyaluronic acid macromolecule, with hyaluronidase remaining the reference standard.

Background/Objectives: Stem cells with the ability to differentiate into other cell types and self-renewal afford a powerful apparatus for the healthcare system to replace and rejuvenate damaged tissues and organs in the treatment of various diseases. For the last few decades, stem cell therapy (SCT) has evolved from being an experimental approach to a recognized clinical treatment. SCT and regenerative medicine have garnered tremendous attention and become prominent tools, especially in treating chronic and acute disease and addressing organ failures, and in their repair and replacement, which are directly associated with human health, life, and longevity. Methods: In this review, after providing a brief history and need for the SCT, the employed delivery techniques utilizing various biomaterials, as well as recent developments in nanotechnological methods, are presented. It is focused on the current literature for the recent progress of stem cell therapy and tissue engineering for the application fields in neurological, ophthalmological, cardiovascular, orthopedic, and oncology, followed by the challenges associated with their applications. Results: In addition to safety concerns, challenges such as uncontrollable differentiations, genetic and epigenetic instability, limited cell survival and integration, immunological rejections, scaling and manufacturing drawbacks, as well as unpredictable behaviors and clinical limitations were reviewed. Conclusions: Future aspects with respect to regenerative medicine and tissue engineering, gene editing and personalized therapies, immunomodulation and anti-inflammatory applications, as well as neuroregeneration and treatment of neurodegenerative disorders are reflected.

Cardiovascular disease affects millions of people around the world every year. Many disease conditions require repair or replacement of the damaged vessels. Atherosclerosis, aneurysms, traumatic injuries, complications after implanted stents, and other conditions may lead to the need for partial or total replacement of a small or large blood vessel. In this study, polyvinyl alcohol (PVA) was used as a biomaterial to construct sections of large artificial blood vessels, simulating portions of a large artery like the aorta or any of its main branches. Once constructed, the prepared blood vessels' mechanical properties were compared to those of sections of porcine aorta. Specifically, the PVA‐based artificial blood vessels (ABV) were evaluated for stiffness, elasticity, and breaking point in tensile strength tests. The effects of variations in PVA concentration and number of processing freeze–thaw cycles were evaluated. Besides the mechanical properties, the prepared blood vessels' biocompatibility was assessed by contacting them L929 mouse for 24 h and found biocompatible. Moreover, adsorption tests for α‐glucosidase enzyme, normally present in the blood, revealed that PVA‐based ABV did not significantly uptake this enzyme or affect its activity suggesting the ABV will not affect the concentration of the enzyme in blood as used as a replacement organ. Furthermore, the hemolysis and blood clotting tests affirmed that the prepared ABVs can be safely used without affecting the blood clotting mechanism. Additionally, Fe(II) ion chelating ability of the artificial blood further ensures that these materials do not compete or interfere with the oxygen carrying ability of the blood. The use of PVA as a potential material for artificial blood vessels could allow repair/replacement of seriously damaged blood vessels due to atherosclerosis and plaque complications, aneurysms, traumatic injury, and other vessel wall alterations. There is also high potential for further improvements leading to the development of novel hybrid systems aimed at the creation of new avenues for practical applications in healthcare.

Here, cryogels of cellulose derivatives, carboxymethylcellulose (CMC) with varying degrees of substitution (DS) of 0.7, 0.9, and 1.2 denoted as CMC ^0.7 , CMC ^0.9 , and CMC ^1.2 , and hydroxypropyl methylcellulose (HPMC) were prepared at cryogenic conditions, − 20 °C. The cryo-crosslinking reaction using divinylsulfone (DVS) as crosslinking at 100 mol% ratio cellulose-derivates (based on the repeating CMC and HPMC unit) is accomplished. The S–O peaks about 1100 and 1250 cm ⁻¹ wavelength in FT-IR spectra of cryogels and interconnected super pores in 50–500 µm size ranges from SEM images confirmed the chemical crosslinked CMC and HPCM cryogel synthesis. The DS of CMC influenced the swelling, degradation, and blood compatibility results of CMC-based cryogels. The CMC ^0.7 cryogel showed the highest swelling ratio%, 1991 ± 23% in PBS and highest hydrolytic degradation%, with 24 ± 4.8% weight loss within 7 days among all CMC-based cryogels. Additionally, all cellulose derivative cryogels were found to be hemocompatible with less than 3% hemolysis and more than 80% blood clotting index values and exhibited nontoxicity with more than 95% cell viability on L929 fibroblast even at high concentration, 1 mg/mL concentration. These findings indicate that these cryogels are excellent materials for tissue engineering and regenerative medicine as the porosity and degradation parameter can be readily controlled to promote cell proliferation and nutrient diffusion for different cells and tissues.

Nitrogen-doped carbon dots (CDs) were prepared from essential fluorescent amino acids, such as lysine (Lys), phenylalanine (Phe), tyrosine (Tyr), and trypt

The widespread use of herbicides such as paraquat and glyphosate is a serious environmental and health concern due to their persistence, mobility, and toxicity in aquatic ecosystems. Composites of alginic acid (Alg) are prepared with carbonaceous materials such as graphene oxide (GO), carbon particles (CPs), porous carbon particles (PCPs), carbon black (CB), and carbon nanotubes (CNTs) were synthesized and evaluated as sorbents for the removal of cationic herbicide paraquat and the anionic herbicide glyphosate. The resulting Alg-based beads are environmentally safe because of the materials used during their preparation, such as a biopolymer, Alg, carbonaceous substances (GO, CPs, PCPs, and CB) as composite moieties, and Ca(II) ions as cross-linkers. The Alg–bead composite possessed strong swelling ability ranging from 1700% to 2500%, which led to swollen beads of spherical shape and an average diameter of 3 mm, each containing 20% of carbonaceous materials. Amongst all Alg-based beads prepared for paraquat and glyphosate removal from the aquatic environment, the highest adsorption capacity was attained for Alg–porous carbon particle (Alg-PCP) composites. The Alg-PCP beads were capable of adsorbing 85.7 ± 2.9 mg/g and 31.6 ± 2.2 mg/g from 50 mL of 250 ppm solutions of paraquat and glyphosate, respectively. In contrast, bare Alg beads adsorbed only 39.7 ± 1.8 mg/g and 12.9 ± 1.7 mg/g, respectively. A 250 mg Alg-PCP bead composite achieved a 91% removal of paraquat from a 50 mL solution containing 250 ppm of paraquat. These results show that Alg–PCP can be used to mitigate herbicide contamination in water, protecting aquatic ecosystems and addressing associated environmental and health risks.