Citrus fruits processing results in the generation of huge amounts of citrus by-products, mainly peels, pulp, membranes, and seeds. Although they represent a major concern from both economical and ...environmental aspects, it is very important to emphasize that these by-products contain a rich source of value-added bioactive compounds with a wide spectrum of applications in the food, cosmetic, and pharmaceutical industries. The primary aim of this review is to highlight the great potential of isolated phytochemicals and extracts of individual citrus by-products with bioactive properties (e.g., antitumor, antimicrobial, antiviral, antidiabetic, antioxidant, and other beneficial activities with health-promoting abilities) and their potential in pharmaceutical, biomedical, and biological applications. This review on citrus by-products contains the following parts: structural and chemical characteristics; the utilization of citrus by-products; bioactivities of the present waxes and carotenoids, essential oils, pectins, and phenolic compounds; and citrus by-product formulations with enhanced biocactivities. A summary of the recent developments in applying citrus by-products for the treatment of different diseases and the protection of human health is also provided, emphasizing innovative methods for bioaccessibility enhancements (e.g., extract/component encapsulation, synthesis of biomass-derived nanoparticles, nanocarriers, or biofilm preparation). Based on the representative phytochemical groups, an evaluation of the recent studies of the past six years (from 2018 to 2023) reporting specific biological and health-promoting activities of citrus-based by-products is also provided. Finally, this review discusses advanced and modern approaches in pharmaceutical/biological formulations and drug delivery (e.g., carbon precursors for the preparation of nanoparticles with promising antimicrobial activity, the production of fluorescent nanoparticles with potential application as antitumor agents, and in cellular imaging). The recent studies implementing nanotechnology in food science and biotechnology could bring about new insights into providing innovative solutions for new pharmaceutical and medical discoveries.
In this study, an efficient utilization and valorization of mandarin peel (Citrus unshiu Marc. var. Kuno) was investigated using innovative and green extraction techniques. The first step of this ...study included the extraction and analysis of the volatile compounds by performing a supercritical CO2 (SC-CO2) extraction under different operating pressure conditions (100 and 300 bar). The analysis of volatile compounds of the obtained extracts was conducted by gas chromatography-mass spectrometry (GC-MS), and limonene was found to be the dominant volatile component (13.16% at 100 bar; 30.65% at 300 bar). After SC-CO2 treatment, the exhausted citrus peel waste enriched with bioactive compounds was subjected to subcritical water extraction (SWE) in a wide temperature range (130–220 °C) using different solvent-solid ratio (10–30 mL/g) in time periods from 5 to 15 min, in order to obtain bioflavonoids. Identification and quantification of present bioflavonoids was conducted by high-performance liquid chromatography with a with a diode array detector (HPLC), and hesperidin (0.16–15.07 mg/g) was determined as the most abundant flavanon in mandarin peel with other polyphenolic compounds that were possible by-products of thermal degradation. At higher temperatures, the presence of 5-hydroxymethylfurfural (5-HMF) and chlorogenic acid were detected. Antiradical activity and total phenolic content in the extracts were determined using spectrophotometric methods, while the process optimization was performed by response surface methodology (RSM).
The fluorescent carbon quantum dots (CQDs) represent an emerging subset of carbonaceous nanomaterials, recently becoming a powerful tool for biosensing, bioimaging, and drug and gene delivery. In ...general, carbon dots are defined as zero-dimensional (0D), spherical-like nanoparticles with <10 nm in size. Their unique chemical, optical, and electronic properties make CQDs versatile materials for a wide spectrum of applications, mainly for the sensing and biomedical purposes. Due to their good biocompatibility, water solubility, and relatively facile modification, these novel materials have attracted tremendous interest in recent years, which is especially important for nanotechnology and nanoscience expertise. The preparation of the biomass-derived CQDs has attracted growing interest recently due to their low-cost, renewable, and green biomass resources, presenting also the variability of possible modification for the enhancement of CQDs’ properties. This review is primarily focused on the recent developments in carbon dots and their application in the sensing of different chemical species within the last five years. Furthermore, special emphasis has been made regarding the green approaches for obtaining CQDs and nanomaterial characterization toward better understanding the mechanisms of photoluminescent behavior and sensing performance. In addition, some of the challenges and future outlooks in CQDs research have been briefly outlined.
Carbon quantum dots (CQDs) have recently emerged as innovative theranostic nanomaterials, enabling fast and effective diagnosis and treatment. In this study, a facile hydrothermal approach for ...N-doped biomass-derived CQDs preparation from Citrus clementina peel and amino acids glycine (Gly) and arginine (Arg) has been presented. The gradual increase in the N-dopant (amino acids) nitrogen content increased the quantum yield of synthesized CQDs. The prepared CQDs exhibited good biocompatibility, stability in aqueous, and high ionic strength media, similar optical properties, while differences were observed regarding the structural and chemical diversity, and biological and antioxidant activity. The antiproliferative effect of CQD@Gly against pancreatic cancer cell lines (CFPAC-1) was observed. At the same time, CQD@Arg has demonstrated the highest quantum yield and antioxidant activity by DPPH scavenging radical method of 81.39 ± 0.39% and has been further used for the ion sensing and cellular imaging of cancer cells. The obtained results have demonstrated selective response toward Fe3+ detection, with linear response ranging from 7.0 µmol dm−3 to 50.0 µmol dm−3 with R2 = 0.9931 and limit of detection (LOD) of 4.57 ± 0.27 µmol dm−3. This research could be a good example of sustainable biomass waste utilization with potential for biomedical analysis and ion sensing applications.
Konzumacija svježih citrusa, ali i njihova prerada generiraju nusproizvode, kao što su kora, sjemenke, pulpa, kao i otpadne vode. Cilj ovog istraživanja je valorizacija agroindustrijskih nusproizvoda ...(kore citrusa) kao vrijedne sirovine za ekstrakciju polifenola primjenom inovativne netermalne metode ekstrakcije sa zelenim otapalom (voda). U ekstraktima je kvantificirano i identificirano ukupno šest fenolnih spojeva. Pri tome je promatran utjecaj vremena (od 5 do 15 min), frekvencije (od 40 do 100 Hz) i omjera kapljevito/kruto (od 200 do 400 ml g−1) na efikasnost procesa ekstrakcije (iskorištenje) i udio dominantnih fenolnih spojeva (hesperidina i narirutina). Uz pomoć metode odzivnih površina definirani su optimalni parametri promatranog procesa ekstrakcije za svaki od istraživanih odziva, i to za iskorištenje (285,93 ml g−1, 73,38 Hz i 14,84 min), za hesperidin (366,19 ml g−1, 97,56 Hz i 5,1 min) te za narirutin (200 ml g−1, 70 Hz i 15 min). Ekstrakcija potpomognuta visokonaponskim električnim pražnjenjem (HVED ekstrakcija) pokazala se pogodnom za ekstrakciju fenolnih spojeva, pri čemu je izbjegnuta uporaba organskih otapala.
The search for an efficient drug or inhibitor in the formation process of kidney stones has been a promising research topic towards reducing the risks of the formation of disease. However, several ...challenges have been faced in investigating the most common constituents of kidney stones, calcium oxalate and its hydrate forms (COM, COD and COT). This study focuses on the preparation and structural characterization (TG, XRD, FTIR, SEM) of calcium oxalate hydrates in the presence of gallic acid (GA) and by varying operating parameters such as temperature (25 °C, 36.5 °C and 48 °C), pH (5.6, 6.5 and 7.5) and amount of added GA (ranging from 100 mg to 1000 mg). Response surface methodology was applied in order to evaluate the effects of operating parameters in the formation of COM and COD, and for the process optimization towards maximizing their content in samples. The results indicated that GA inhibited the formation of COM (0–100%) and promoted the formation of COD (0 ≤ 99%), while a medium pH and the amount of added GA showed a significant effect in the process of COD formation. In order to investigate the interactions established in the formation process and the possible adsorption between GA and the formed crystals, electrochemical measurements were performed.
In this study, three different precipitation systems of increasing complexities were used to study formation of calcium oxalate hydrates under hyperoxaluria conditions. For this purpose, three ...different precipitation systems have been studied: (a) a simple system (a system containing constituent ions), (b) NaCl system (a system consisted of constituent ions and 0.3 mol dm
−3
NaCl), and (c) artificial urine system (a system containing constituent ions that are of the type and quantity mimicking real urine) at initial pH (pH
i
= 6.5) value, with and without added vitamin C. The vitamin C has been extensively tested for its ability to inhibit or promote the process of calcium oxalate precipitation or the formation of specific hydrate modification. In order to determine whether calcium oxalate crystallization could be affected by the presence of vitamin C in precipitation systems with increasing complexity, different amounts of vitamin C (in the mass range from 100 to 1000 mg) were added to the precipitation systems. The results indicated that in all investigated simple systems, calcium oxalate monohydrate (COM) is observed to be dominant precipitated hydrate phase, while in NaCl systems precipitation of COM and calcium oxalate trihydrate (COT) mixture occurrs, except in reference NaCl system (without addition of vitamin C) where COM precipitated exclusively. In reference artificial urine system, calcium oxalate dihydrate was observed to be dominant precipitated hydrate phase, while addition of vitamin C promoted precipitation of COT. Significant differences are mainly observed in crystal morphology and the content of individual hydrate phases. Electrochemical measurements have indicated the existence of electrostatic interactions between seed crystals and ascorbic acid, even at low masses of added vitamin C.
This work reports the preparation of amino acid-functionalized CQDs from citric acid by facile hydrothermal synthesis. The prepared N-doped CQDs exhibited excellent optical, physical, and chemical ...properties, and the differences were observed among the six different amino acids used as nitrogen dopants (Leu, Trp, Lys, Arg, Ala, His). Compared to the blank sample (without the addition of amino acids), N-doped CQDs have shown significantly higher quantum yield, also demonstrating the potential in metal ion sensing. The highest quantum yield of 36.45%, with a peak excitation/emission of 340/406 nm, was achieved using citric acid and amino acid Leu (CQD@Leu), treated at temperature of 180 °C during 9 h. The prepared samples were investigated toward metal ion selectivity (Ca2+, Cu2+, Fe3+, K+, Hg2+, Mg2+, Al3+, Mn2+, and Na+), and the CQD@Leu showed a selective and sensitive response upon the addition of Fe3+ ions. Therefore, CQD@Leu was selected for further investigation in Fe3+ detection in the model system and real well water samples. A developed model was described by a logistic function with a good coefficient of determination of R2 = 0.9982, while the linear range was determined in the concentration range from 0.3 mol dm−3 to 30 mol dm−3, with a determined limit of detection of LOD = 1.77 ± 0.01 mol dm−3 and limit of quantification of LOQ = 5.89 ± 0.04 mol dm−3. Furthermore, the results of the in vitro cytotoxicity test (MTT) with normal and tumor cell lines (MRC-5, HeLa, NCI-H358, and CaCo-2) clearly demonstrate the excellent biocompatibility of CQD@Leu.
Duhanski otpad je kruti otpad, a njegove vrste međusobno se razlikuju po granulaciji i mjestu izdvajanja u procesu proizvodnje. Cilj ovog rada bio je istražiti učinkovitost eutektičkih otapala u ...ekstrakciji bioaktivnih komponenti iz duhanskog industrijskog otpada (refabrikat, rebro i prašina). Ispitan je utjecaj procesnih parametara (vrijeme miješanja, temperatura i udio vode u otapalu) na svojstva samog ekstrakta (ukupne fenole, antiradikalnu aktivnost, udio klorogenske kiseline i rutina). Metodom odzivne površine određeni su optimalni parametri ekstrakcije (30 min, 70 °C, 29,99 % vode). Provedeno istraživanje ogleda se u maksimalnom iskorištavanju nusproizvoda duhanske industrije, a rezultira visokovrijednim ekstraktima koji se mogu implementirati u druge procese i proizvode.
Tobacco waste is a solid waste highly diverse in granulation and point of separation in the manufacturing process. The objective of this study was to investigate the efficacy of eutectic solvents in the extraction of bioactive compounds from tobacco waste. Influence of extraction parameters on the properties of the obtained extracts (total phenol, antioxidant activity, chlorogenic acid, and rutin) has been determined. Using response surface methodology, optimal parameters were defined (30 min, 70 °C, 29.99 % water). The meaning of the proposed research is reflected in the maximum utilization of the tobacco by-product in order to obtain extracts that can be implemented in other products and processes.
•Argon Ion Implantation on kapton is a more rigid and reliable technology.•Metal oxides such as zinc oxide add up to extend the conventional triboelectric series.•A simple vertical contact separate ...triboelectric nanogenerator is designed.•Biomechanical energy and powering low-power electronics is demonstrated.
The triboelectric nanogenerator (TENG) is a widely used energy-harvesting unit for self-power applications. The electrical output performance of the TENG could be significantly improved by ion implantation and explore new triboelectric materials beyond the conventional triboelectric series. In this present work, the phase pure hydrothermally synthesized ZnO particles, argon ion-implanted Kapton acted as a positive triboelectric layer while pure Kapton behaved as a negative triboelectric layer. The atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM) were performed to investigate the surface roughness and surface potential of the triboelectric materials utilized in vertical contact mode TENG (I-TENG, abbreviated further). The elemental mapping and X-ray photoelectron spectroscopy (XPS) results suggested successful Argon-ion implantation upon Kapton. Finally, the I-TENG device was subjected to various forces to systematically depict its electrical output responses and power up a wrist-watch and calculator.
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