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Aloe vera-derived Ag-doped TiO2 nanoparticles immobilized by chitosan films for photo(electro)catalytic and antimicrobial functions
(Elsevier, 2025) Kaba, İbrahim; Bozkurt, Rabia Nur; Altıner Kurt, Eda; Kerkez Kuyumcu, Özge; Koca, Atıf
In this study, as an environmentally friendly and sustainable approach, TiO2 nanoparticles (TiO2 NPs) were prepared by green synthesis method using deep eutectic solvent (DES, ChCl/glycerol (1:2)) based Aloe vera leaves extract obtained by Soxhlet extraction. The DES system functioned concurrently as a green solvent and a functional medium, while the bioactive chemicals in the Aloe vera leaves extract operated as natural reducing and stabilizing agents. The produced TiO2 NPs were doped with silver (Ag) at molar ratios of 0.25, 0.50, and 0.75, and immobilized on a chitosan matrix (Ag/TiO2-CS) to facilitate recovery from the reaction media. The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), photoluminescence (PL) spectroscopy, scanning electron microscopy-energy dispersive X ray analysis (SEM-EDX) and X-ray photoelectron spectroscopy (XPS). Characterization validated the TiO2 phase, effective Ag incorporation, diminished band gap energy (from 3.34 eV to 2.83 eV), and uniform nanoparticle distribution. PL measurements confirmed that Ag doping reduces carrier charge recombination. The 0.50Ag/ TiO2-CS film displayed the best photocatalytic degradation efficiency for malachite green (93.3 %) under solar irradiation and exhibited a higher photocurrent response relative to undoped TiO2. Moreover, antimicrobial assays demonstrated that 0.50 and 0.75 Ag/TiO2 NPs exhibited significant suppression of S. aureus and E. coli, with low minimum inhibitory concentrations (MIC) (0.40–0.20 µg/mL) and minimum bactericidal concentra tions (MBC), signifying robust bactericidal efficacy. The findings indicate that DES-assisted Aloe vera-mediated synthesis provides an economical and scalable method for producing multifunctional nanocomposites with considerable potential in environmental remediation and biomedical fields.
Coordination-driven assembly of alginate networks: From egg-box structures to bioactive delivery applications
(MDPI Publishing, 2026) Toprakçı, İrem; Kurtulbaş, Ebru; Bozkurt, Rabia Nur; Şahin, Selin
Alginate is a biodegradable and renewable natural polysaccharide that has been extensively investigated for the design of macromolecular delivery systems. This review presents an overview of alginate-based microparticles regarding the relationship between molecular structure, gelation behavior, and functional performance. The impacts of main structural parameters (mannuronic to guluronic acid (M/G) ratio, molecular weight, and block distribution) are discussed comprehensively. Particular attention is given to Ca2+-mediated ionic gelation, including egg-box junction zone formation and the development of three dimensional hydrogel networks. Different production strategies such as external and internal gelation, emulsification, and microfluidic approaches are evaluated in terms of their impact on particle morphology and network homogeneity. In addition, the effects of formulation and process parameters on encapsulation efficiency, mechanical stability, and mass transfer behavior are analyzed. Furthermore, release mechanisms are discussed in relation to network structure and polymer-solute interactions. The environmental significance of alginate-based systems is also emphasized as sustainable alternatives to synthetic polymeric carriers.
Designing a sustainable extraction platform using deep eutectic solvents: Valorization of sidr leaves into bioactive-rich fractions
(SAGE Publications, 2026) Şahin, Selin; Bozkurt, Rabia Nur; Kurtulbaş, Ebru; Toprakçı, İrem
Sidr (Ziziphus spina-christi L.) leaves are a potential source of phenolic bioactives exhibiting promising an tioxidant properties. A sustainable extraction system based on deep eutectic solvents (DESs) was developed for the recovery of bioactive-rich extract from Sidr leaves in the present study. Methods: Six DES systems prepared from glycerol with lactic acid or propionic acid were screened. Fourier transform infrared (FTIR) spectroscopy confirmed DES formation through shifts and broadening of characteristic bands associated with hydrogen bonding interactions. Glycerol:propionic acid (1:1) was selected as the most effective solvent by principal component analysis (PCA). Extraction parameters were optimized by Box- Behnken design using immersion time, water addition and sample mass as variables. Results: Total phenolic content (TPC) were between 10.10 mg-GAE/g-DM and 61.23 mg-GAE/g-DM, while rutin content varied from 4.69 mg/g to 32.50 mg/g. Water addition was the most influential factor for phenolic recovery. The optimized conditions were 30 min, 30% water addition and 0.948 g sample mass. Antioxidant activity correlated with TPC and total flavonoid content (TFC). Conclusion: Antioxidant capacity of the Sidr leaf extract is mostly contributed by phenolic matrix rather than an individual compound.
Elucidating deep eutectic solvent-mediated recovery of phenolic compounds from cubeb pepper (piper cubeba l.f.) and their antioxidant potential
(SAGE Publications, 2026) Bozkurt, Rabia Nur; Kurtulbaş, Ebru; Toprakçı, İrem; Topraksever, Nükte
Objective: Conventional extraction methods for phenolic recovery often rely on large amounts of organic solvents and may exhibit limited efficiency. This study aimed to develop and optimize a sustainable deep eutectic solvent (DES)-assisted automatic solvent extraction (ASE) process for the recovery of phenolic compounds from Piper cubeba L.f. fruits. Methods: Prepared DES systems were characterized by Fourier-transform infrared (FTIR) spectroscopy to confirm DES formation and investigate intermolecular hydrogen-bond interactions between their constituent components. Different DES systems were screened and compared using principal component analysis (PCA) to identify the most effective extraction medium. The selected DES system, lactic acid:ethylene glycol (2:1), was subsequently optimized using response surface methodology (RSM) based on a Box–Behnken design. Immersion time, water addition, and sample mass were evaluated as the main extraction variables. Results: The extraction parameters significantly influenced total phenolic content (TPC), antioxidant activity, and 2-hydroxycinnamic acid recovery. TPC values ranged from 25.55 to 71.54 mg-GAE/g-DM. Antioxidant activity varied between 17.41 and 32.90 mg-TEAC/g-DM for the DPPH assay and between 8.93 and 32.51 mg-TEAC/g-DM for the ABTS assay. The content of 2-hydroxycinnamic acid ranged from 5.95 to 26.12 mg/g-DM. Optimum extraction conditions were determined as 24.95 min immersion time, 52.55% water addition, and 0.70 g sample mass, with prediction errors below 2%. Conclusion: DES-assisted ASE enabled efficient phenolic recovery and accurate process optimization, demonstrating its potential as a sustainable alternative to conventional solvent-based extraction methods. The findings highlight the suitability of the lactic acid:ethylene glycol (2:1) DES system for enhancing the extraction of bioactive compounds from P. cubeba fruits and support its potential application in food, nutraceutical, pharmaceutical, and cosmetic formulations.
Green recovery of phenolic-rich extracts from pineapple crowns using deep eutectic solvents: FTIR characterization and chemometric optimization
(MDPI Publishing, 2026) Ertaş, Ayşe Nur; Akkın, Zeynep Azra; Bozkurt, Rabia Nur; Toprakçı, İrem; Cadar, Oana; Şahin, Selin
This study presents an integrated green analytical strategy combining deep eutectic solvent (DES) screening, Fourier transform infrared spectroscopy (FTIR), principal component analysis (PCA), and Box–Behnken response surface optimization for the valorization of pineapple crowns, an underexplored agro-industrial by-product. An ultrasound-assisted extraction (UAE) method was developed using DESs to obtain phenolic-rich extracts from pineapple (Ananas comosus) crowns. Five DES formulations were characterized by FTIR to evaluate their characteristic vibrational features, while extraction performance was assessed using total phenolic content (TPC) and antioxidant activity determined by the DPPH assay. Among the tested solvents, glycerol/urea (1:1, molar ratio) exhibited the highest extraction performance based on TPC and antioxidant activity measurements. PCA was used as a complementary tool to visualize the relationships among the DES formulations. Following preliminary temperature screening, 50 ◦C was selected for the optimization experiments. The extraction conditions were optimized using a Box–Behnken design coupled with response surface methodology (BBD–RSM), while desirability function analysis was applied to identify the optimum extraction conditions. The predicted optimum conditions were a sample mass of 1.09 g, an extraction time of 24.75 min, and a water content of 38.21%, yielding predicted responses of 34.66 mg GAE/g air-dried sample (ADS) for TPC and 12.30 mg Trolox equivalent antioxidant capacity (TEAC)/g-ADS for antioxidant activity. Experimental confirmation at the optimum showed deviations below 2% between predicted and observed responses, supporting the adequacy of the models. The quadratic models showed high goodness of fit (R2 = 0.9871 for TPC, and R2 = 0.9906 for antioxidant activity). Overall, the integration of DES-based UAE, FTIR characterization, PCA, and chemometric optimization provides a sustainable analytical approach for producing phenolic-rich extracts from pineapple crown biomass.
Green synthesis of titanium dioxide nanoparticles using a deep eutectic solvent-based extract of Prunus spinosa L. for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid
(Elsevier, 2026) Bozkurt, Rabia Nur; Şahin, Selin; Cadar, Oana
In this study, polyphenol-rich extract obtained from Prunus spinosa L. fruit using choline chloride/lactic acid (1/ 1) deep eutectic solvent was used as reducing, stabilizing and capping agent in the green synthesis of TiO2 nanoparticles (TiO2-NPs). The extraction system using a homogenizer was optimized using the Response Surface Methodology (RSM). The conditions providing the highest efficiency for total phenolic content (40.885 mg-GAE/ g-FF) and antioxidant activity (86.22%) were determined as 46.179% (v/v) water ratio to DES, 1.478 g sample amount and 65.513 s extraction time. UV–Vis DRS, PL, SEM-EDX, HR-TEM-EDX, FTIR, XRD, DLS, and Zeta Potential analyses revealed that the TiO2-NPs had a band gap of 2.8 eV, a spherical morphology, nanosize, and high crystalline purity. Comparative DLS and zeta potential analyses of aqueous extract and DES-based systems showed that the DES-based environment yields smaller and more stable TiO2-NPs. Furthermore, TiO2-NPs showed notable antioxidant activity, with an IC50 value of 52.4 μg/mL. The TiO2-NPs were utilized as photo catalysts to degrade 2,4-dichlorophenoxyacetic acid (2,4-D). Photocatalytic tests showed the highest efficiency, achieving 66.9% degradation of an 80 mg/L 2.4-D solution with 50 mg of TiO2-NPs at pH 5.5 within 120 min. The photocatalyst remained stable after three cycles. A nanomaterial has been sustainably created using an extremely environmentally friendly method for photocatalytic pollutant destruction.
Green synthesis of zinc oxide nanoparticles including Rosehip (Rosa canina L.) seed extract: Evaluation of its characterization and bioactivity properties
(Wiley, 2024) Bozkurt, Rabia Nur; Şahin, Selin
The use of bioactive compounds in plants as reducing, stabilizing, and capping agents in nanoparticle manufacturing is an exceptionally eco-friendly approach. This work used rosehip seed extract, acquired by automatic solvent extraction, in the microwave-assisted green production of zinc oxide nanoparticles (ZnO NPs). The total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of the extracted materials and nanoparticles were assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The ideal synthesis parameters were established as 25 mL of extract, pH 12, 360 W of microwave power, and a metal salt concentration of 0.05 M for a duration of 7 minutes. The characterization of the ZnO NPs synthesized under these conditions was performed using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), dynamic light scattering (DLS), zeta potential measurements, and UV-Vis spectrophotometry. High-purity, nano-sized, antioxidant ZnO NPs were manufactured using an ecologically friendly, sustainable, and ecological technique.
Green-synthesized CuO/Cu2O-supported g-C3N4 p–n junction photocatalyst for photo(electro)catalytic hydrogen evolution
(Elsevier, 2026) Kaba, İbrahim; Kılıç, Behris; Bozkurt, Rabia Nur; Koca, Atıf
In this study, an environmentally friendly CuO/Cu2O nanoparticle (NPs) production method was developed using waste rosehip seed plant extracts as reducing and stabilizing agents. Automatic solvent extraction (ASE) with a green 60% (v/v) ethanol/water solvent combination produced polyphenol-rich solutions for biogenic nanoparticle production. Green CuO/Cu2O NPs were loaded onto n-type graphitic carbon nitride (g-C3N4, CN) at 5%, 10%, and 15% weight percentages to form p-n heterojunction photocatalysts (5CuO/Cu2O@CN, 10CuO/Cu2O@CN, and 15CuO/Cu2O@CN). Structural and morphological analyses and material characterizations performed using XRD, FTIR, SEM-EDS, TEM, XPS, UV–vis DRS, Zeta Sizer, and DLS confirmed the successful formation and homogeneous distribution of CuO/Cu2O on the CN surface. Optical and photoelectrochemical characterizations revealed that the formation of p–n type junction significantly increased visible light absorption and supported efficient charge carrier dissociation. Photoelectrochemical (PEC) measurements yielded consistent results for photocatalytic hydrogen (H2) evolution, with a consistent H2 evolution relationship; pure CN produced 125 μmol g− 1 h− 1 H2, while the 10CuO/Cu2O@CN sample produced 937 μmol g− 1 h− 1 H2, increasing performance by approximately 7.5-fold. Furthermore, this study aimed to contribute to a more environmentally friendly and sustainable approach by using lactic acid as a sacrificial material to facilitate hole consumption. In addition to photocatalytic activity, the antioxidant properties of the photocatalysts were evaluated using 2,2-diphenyl-1-picrylhydrazil (DPPH) free radical scavenging method, and composition-dependent radical scavenging efficiencies were determined.
Investigation of photocatalytic degradation of methyl orange using zinc oxide-supported chitosan hydrogel beads
(Taylor & Francis, 2025) Kaba, İbrahim; Bozkurt, Rabia Nur; Kılıç, Behris
In this study, chitosan-based ZnO supported hydrogels (CZ–H) were synthesized to evaluatetheir photocatalytic degradation performance against methyl orange (MO) dye. The compos-ite hydrogels were characterized using X-ray Diffraction (XRD), UV–Vis DRS, ScanningElectron Microscopy (SEM-EDS), Thermogravimetric Analysis (TGA), and Fourier TransformInfrared Spectroscopy (FTIR). These characterization results confirmed the successful forma-tion of the CZ–H composite structure. The band gap of the composite was approximately2.77 eV, supporting enhanced photocatalytic activity. Photocatalytic experiments showedthat CZ–H removed 74% of MO within 60 min, compared to 42% for pure chitosan beads,with reaction rate constants of 0.0237 min−1 and 0.0113 min−1, respectively. Moreover, theCZ–H beads demonstrated good reusability with minimal loss in efficiency over multiplecycles. These findings highlight the potential of CZ–H as a stable, effective, and reusablephotocatalyst for the efficient removal of dyes from wastewater.
Phocatalytic dye degradation activities of chitosan film modified by green synthesized tio2 from aloe vera leaf extract
(Avestia Publishing, 2025) Kaba, İbrahim; Bozkurt, Rabia Nur; Kerkez Kuyumcu, Özge; Koca, Atıf
Recent research focuses on heterogeneous photocatalysis, an environmentally friendly and cost-effective method that uses solar energy to completely degrade pollutants without generating secondary waste. The focus is optimizing the properties of photocatalysts in terms of electronic structure, light absorption, and reduced recombination rate of photogenerated charges and easy separation of the photocatalyst from reaction media [1]. The potential for efficient, sustainable heterogeneous photocatalysis has been demonstrated by semiconductors such as TiO₂, ZnO, Fe₂O₃, CdS, CuS, and ZnS [2]. TiO₂ is regarded as one of the most effective photocatalysts. The usage of TiO₂ for the degradation of hazardous organic dyes in wastewater has significant potential. The separation of the photocatalyst from the reaction medium remains a significant challenge in photocatalytic applications. In particular, the recovery of TiO₂ after the degradation of organic dyes poses a considerable difficulty, as its fine particulate nature hampers efficient separation from the treated solution. One of the strategies in this regard is the immobilization of the photocatalyst by embedding it into a polymer matrix. This approach facilitates easier separation of the photocatalyst from the reaction medium [3]. Chitosan, a natural biopolymer widely used for its biodegradability and biocompatibility, is an attractive candidate for hydrogel development due to its functional groups that serve as cross-linking sites during hydrogel formation. It has also been combined with photocatalysts and utilized in numerous studies [4-6]. In this study, green-synthesized TiO₂-embedded chitosan films (Bio-TiO₂-CS films) prepared using aloe vera leaf extract offer the advantage of facile separation after the degradation process, as well as potential reusability following dye removal. As the goal of the study, it is believed that the obtained chitosan film hydrogels can be used as an effective bio-template material to disperse TiO2 nanostructures due to their three-dimensional porous structure and appropriate nanopore size distribution, and this feature has led us to investigate the simpler, recyclable, green approach, and biomaterial development of the use of Bio-TiO₂-CS Hydrogel Films in photocatalytic dye removal from water.
Structure-property relationships governing encapsulation and release of antibiotics from calcium–alginate hydrogels
(MDPI Publishing, 2026) Hebip, İbrahim; Toprakçı, İrem; Bozkurt, Rabia Nur; Kurtulbaş, Ebru; Şahin, Selin
Understanding mass transport of structurally different drugs within ionically crosslinked hydrogel networks remains an important challenge in polymer-based delivery systems. In this study, hydrophilic amoxicillin (AMOX) and amphiphilic doxycycline (DOX) were encapsulated into calcium–alginate beads, respectively. A three-factor and three-level Box AcademicEditor: AdinaMagdalena Musuc Received: 10June2026 Revised: 11July2026 Accepted: 14July2026 Published: 16 July 2026 Copyright: ©2026bytheauthors. Licensee MDPI,Basel,Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY)license. Behnken design was utilized to examine the influences of alginate concentration (2–5%, w/v), CaCl2 concentration (1–3%, w/v), and gelation time (15–45 min) on encapsulation efficiency (EE). EE exhibited considerable variability for both AMOX (10–86%) and DOX (10–63%). Optimal EE values were achieved at almost 3.5% alginate and 3% CaCl2. The optimized gelation times differed between AMOX (45 min) and DOX (15 min), which is likely associated with differences in their physicochemical properties, although additional intermediate gelation times could further refine the optimal conditions. ANOVA identified CaCl2 concentration and the quadratic effect of alginate as the most influential parameters. Furthermore, both models demonstrated robust predictive capability (R2 > 0.98). In vitro release experiments demonstrated minimal drug diffusion in simulated gastric fluid (SGF) and significantly accelerated release in simulated intestinal fluid (SIF). These findings indicate a pH-responsive release behavior under simulated gastrointestinal conditions. The release profile was best represented by Higuchi and Korsmeyer–Peppas kinetic models. SEM and optical microscopy revealed uniform spherical beads with drug-dependent microstructural differences: hydrophilic AMOX produced smoother, wrinkled surfaces, whereas amphiphilic DOX induced localized cracking and heterogeneous microdomains. Furthermore, DLS and zeta potential measurements of the released fractions indicated nanoscale particle populations (≈190–225 nm) with moderate negative surface charge (≈−21 mV), suggesting stable colloidal dispersion during intestinal-phase release.
Sustainable extraction of bioactive compounds: Engineering principles and technologies
(Wiley, 2026) Bozkurt, Rabia Nur; Kurtulbaş, Ebru; Toprakçı, İrem; Şahin, Selin
There is an increasing demand for sustainable extraction technologies capable of efficiently isolating bioactive compounds from complex food matrices due to the rising interest in nutraceutical products. Traditional extraction procedures that use conventional solvents have big problems (environmental impact, solvent toxicity, and high energy consumption). Green extraction technologies are safer and more environmentally friendly options following the rules of green chemistry. This review provides a comprehensive overview of green extraction strategies applied to food matrices. Their methods, benefits, and process efficiency are examined through the impact of food matrix structure on extraction performance. Special focus is placed on the use of food-grade and alternative solvents, which enhance extraction efficiency while providing safety and environmental sustainability. In conclusion, green extraction technologies contribute to waste valorization, whereas they facilitate the efficient manufacture of high-quality functional components. So, this approach makes them a feasible strategy for the sustainable recovery of nutraceutical compounds.
Sustainable synthesis of ZnO nanoparticles from melon (cucumis melo l.) by-products: RSM optimization, structural characterization, antioxidant activity, and photocatalytic performance
(Wiley, 2026) Bozkurt, Rabia Nur; Kaba, İbrahim; Kahraman, Yusuf Sezai; Altınkeser, Tuğçe
This study explores the eco-friendly synthesis of zinc oxide nanoparticles (ZnO-NPs) using polyphenol-rich extracts from melon (Cucumis melo L.) peel and seeds as naturalreducing and stabilizing agents. Optimization via response surface methodology (RSM) determined the ideal synthesis conditions at a 0.078 mol/L metal concentration, 14.73 mL extract, and pH 10.77. Characterization through XRD confirmed a hexagonal wurtzite crystal structure with an average size of 21.7 nm, while SEM and TEM imaging revealed predominantly spherical morphologies. UV–visible DRS analysis showed a 368 nm absorption edge with a calculated band gap of 3.21 eV. DLS measurements indicated a hydrodynamic diameter of 135.6 nm with a PDI of 0.206 and a zeta potential of −20.5 mV, confirming good colloidal stability. The resulting NPs exhibited strong antioxidant activity (IC50 = 40.7 µg/mL) and acted as effective heterogeneous photocatalysts for the degradation of organic dyes. Specifically, ZnO-NPs enabled the photodegradation of methyl orange (MO) and methylene blue (MB), achieving 63.56% degradation for 5 mg L−1 MO. These findings demonstrate that melon-waste-derived ZnO-NPs are sustainable and promising candidates for wastewater treatment and environmental remediation.
Tailoring natural solvents: Deep eutectic approach for recovering bioactives from Prunus Spinosa L.
(Wiley, 2025) Bozkurt, Rabia Nur; Falsafi, Seid Reza; Şahin, Selin
In this study, several choline chloride (ChCl)-based deep eutectic solvent (DES) combinations were prepared at different molarratios (1/1, 1/2, and 2/1) using amine (urea), polyols (ethylene glycol and glycerol), and carboxylic acids (lactic acid, formic acid,propionic acid, and acetic acid). The performances of the DESs in the homogeniser-assisted extraction of Prunus spinosa L.fresh fruit were compared depending on the total phenolic content (TPC), total anthocyanin content (TAC), and 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity (antioxidant activity [AA]) yields. Based on the findings of Tukey’s test formultiple comparisons, ChCl/formic acid (2/1) provided the best extraction efficiency with statistically significant differences(p < 0.05). Fourier-transform infrared spectroscopy was used to confirm the formation of the proposed DES. Furthermore, theproposed DES also showed better performance compared to conventional aqueous ethanol (60%, v/v) and water. Then, theselected DES (ChCl/formic acid, 2/1) was employed for the optimization study using the Box-Behnken Design of the responsesurface methodology. The optimum process conditions for the maximum yields of TPC (52.34 mg-GAE/g-FF), TAC (2.09 mg-cyn-3-glu/g-FF), and AA (89.21%) were found to be 50% (v/v) water in the DES, 0.833 g of material, and 69.906 s extractiontime.

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