The Influence of Gamma Radiation on Different Gelatin Nanofibers and Gelatins.

Gelatin nanofibers are known as wound-healing biomaterials due to their high biocompatible, biodegradable, and non-antigenic properties compared to synthetic-polymer-fabricated nanofibers. The influence of gamma radiation doses on the structure of gelatin nanofiber dressings compared to gelatin of their origin is little known, although it is very important for the production of stable bioactive products. Different-origin gelatins were extracted from bovine and donkey hides, rabbit skins, and fish scales and used for fabrication of nanofibers through electrospinning of gelatin solutions in acetic acid. Nanofibers with sizes ranging from 73.50 nm to 230.46 nm were successfully prepared, thus showing the potential of different-origin gelatin by-products valorization as a lower-cost alternative to native collagen. The gelatin nanofibers together with their origin gelatins were treated with 10, 20, and 25 kGy gamma radiation doses and investigated for their structural stability through chemiluminescence and FTIR spectroscopy. Chemiluminescence analysis showed a stable behavior of gelatin nanofibers and gelatins up to 200 °C and increased chemiluminescent emission intensities for nanofibers treated with gamma radiation, at temperatures above 200 °C, compared to irradiated gelatins and non-irradiated nanofibers and gelatins. The electron paramagnetic (EPR) signals of DMPO adduct allowed for the identification of long-life HO● radicals only for bovine and donkey gelatin nanofibers treated with a 20 kGy gamma radiation dose. Microbial contamination with aerobic microorganisms, yeasts, filamentous fungi, Staphylococcus aureus, Escherichia coli, and Candida albicans of gelatin nanofibers treated with 10 kGy gamma radiation was under the limits required for pharmaceutical and topic formulations. Minor shifts of FTIR bands were observed at irradiation, indicating the preservation of secondary structure and stable properties of different-origin gelatin nanofibers.

Germination Study of Some Protein-Based Gels Obtained from By-Products from the Leather Industry on Tomato and Pepper Seeds.

This study aimed to evaluate the biostimulant effects of three protein-based gels, GHC 1-B (20% gelatin (GPU-B) obtained by thermal hydrolysis from residual untanned leather and 80% collagen hydrolysates (HCE-B) obtained by alkaline-enzymatic hydrolysis from residual bovine-tanned leather), GHC 2-B (40% keratin hydrolysate (HKU-B) obtained by alkaline-enzymatic hydrolysis from sheep wool + 40% HCE-B + 20% GPU-B), and GHC 3-B (20% GPU-B + 80% hydrolyzed collagen (HPU-B) obtained by thermal and enzymatic hydrolysis from residual untanned leather). A germination study was carried out on pepper and tomato seeds at concentrations of 1%, 3%, and 10%. As a result of the study, it was found that all three protein-based gels showed a stimulatory effect on the tomato seeds at a 1% concentration, where the Gi (germination index) was ˂100%. The GHC 2-B variant had the highest stimulatory effect (Gi-190.23%). Pepper seeds have proven to be more sensitive to the gel's composition. The concentration at which it proved to be non-inhibitory (Gi-88.29%) was 1% in the case of GHC 2-B. It was found that the presence of hydrolyzed keratin in the composition can be a plus compared to the other two protein gels tested due to its composition, which is richer in phytonutrient compounds (e.g., sulfur molecules).

Fish Scale Gelatin Nanofibers with Helichrysum italicum and Lavandula latifolia Essential Oils for Bioactive Wound-Healing Dressings.

Essential oils are valuable alternatives to synthetic antibiotics that have the potential to avoid the pathogen resistance side effects generated by leather. Helichrysum italicum and Lavandula latifolia essential oils combined with fish scale gelatin were electrospun using a coaxial technique to design new bioactive materials for skin wound dressings fabrication. Fish scale gelatins were extracted from carp fish scales using two variants of the same method, with and without ethylenediaminetetraacetic acid (EDTA). Both variants showed very good electrospinning properties when dissolved in acetic acid solvent. Fish scale gelatin nanofibers with Helichrysum italicum and Lavandula latifolia essential oil emulsions ensured low microbial load (under 100 CFU/g of total number of aerobic microorganisms and total number of yeasts and filamentous fungi) and the absence of Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 10536, and Candida albicans ATCC 1023 as compared to fish scale gelatin without essential oils, which recommends them for pharmaceutical or topical applications. A scratch-test performed on human dermal fibroblasts proved that the biomaterials contributing to the wound healing process included fish scale gelatin nanofibers without EDTA (0.5% and 1%), fish scale gelatin nanofibers without EDTA and Lavandula latifolia essential oil emulsion (1%), fish scale gelatin nanofibers with EDTA (0.6%), and fish scale gelatin nanofibers with EDTA with Helichrysum italicum essential oil emulsion (1% and 2%).

Physico-Chemical Changes Induced by Gamma Irradiation on Some Structural Protein Extracts.

In this study, the effect of gamma irradiation (10 kGy) on proteins extracted from animal hide, scales, and wool was evidenced by calorimetric (µDSC) and spectroscopic (IR, circular dichroism, and EPR) methods. Keratin was obtained from sheep wool, collagen and bovine gelatin from bovine hide, and fish gelatin from fish scales. The µDSC experiments evidenced that gamma irradiation influences the thermal stability of these proteins differently. The thermal stability of keratin decreases, while a resistance to thermal denaturation was noticed for collagen and gelatins after gamma irradiation. The analysis of the IR spectra demonstrated that gamma irradiation determines changes in the vibrational modes of the amide groups that are associated with protein denaturation, most meaningfully in the case of keratin. As evidenced by circular dichroism for all proteins considered, exposure to gamma radiation produces changes in the secondary structure that are more significant than those produced by UV irradiation. Riboflavin has different effects on the secondary structure of the investigated proteins, a stabilizing effect for keratin and fish gelatin and a destabilizing effect for bovine gelatin, observed in both irradiated and non-irradiated samples. The EPR spectroscopy evidences the presence, in the gamma-irradiated samples, of free radicals centered on oxygen, and the increase in their EPR signals over time due to the presence of riboflavin.

Innovative Protein Gel Treatments to Improve the Quality of Tomato Fruit.

This study aims to establish the effect of biostimulatory protein gels on the quality of tomato. One of the most consumed vegetables, tomato (Lycopersicon esculentum Mill.) is a rich source of healthy constituents. Two variants of protein gels based on bovine gelatin and keratin hydrolysates obtained from leather industry byproducts were used for periodical application on the tomato plant roots in the early stage of vegetation. The gels were characterized by classical physicochemical methods and protein secondary structure was obtained by FTIR band deconvolution. After ripening, tomato was analyzed regarding its content of quality indicators (sugars and organic acids) and antioxidants (lycopene, ß-carotene, vitamin C, polyphenols). The results emphasized the positive effects of the protein gels on the quality parameters of tomato fruit. An increase of 10% of dry matter and of 30% (in average) in the total soluble sugars was noted after biostimulant application. Also, lycopene and vitamin C recorded higher values (by 1.44 and 1.29 times, respectively), while ß-carotene showed no significant changes. The biostimulant activity of protein gels was correlated with their amino acid composition. Plant biostimulants are considered an ecological alternative to conventional treatments for improving plant growth, and also contributing to reduce the intake of chemical fertilizers.

Collagen and Keratin Hydrolysates to Delay the Setting of Gypsum Plaster.

Leather and wool waste represent a high concern due to the low level of valorization and circular economy demands for upcycling of biomass resources. Both biomasses can be easily processed as protein hydrolysates and used as functional additives due to the amphiphilic and tunable properties of collagen and keratin proteins. The chemical, physical, and structural investigations of collagen and keratin hydrolysate properties showed that the chelating abilities due to carboxylic groups can be exploited for gypsum retardant additives. The molecular weights and amino acid compositions of three different hydrolysates showed only slight influences on the setting time of gypsum; all three proteins delayed the setting time of gypsum between 60 and 120 min, as compared to the commercial plaster with a 30 min setting time. Higher molecular weight and more carboxylic active groups showed slight improvements in the setting time of mortars. The improved properties of keratin hydrolysate as compared to low molecular collagen hydrolysate were attributed to foaming and conductive properties. The mechanism of mortar setting delaying through calcium ions complexation by protein hydrolysates was shown by electric conductivity evolution of plasters with and without protein additives over time, supported by foaming properties, amino acid, and functional groups' composition. Lower bending strength values for the higher concentration of proteins do not reduce the potential to use the protein hydrolysates as retardant additives in mortar fabrication.

Luminescence, Paramagnetic, and Electrochemical Properties of Copper Oxides-Decorated TiO2/Graphene Oxide Nanocomposites.

The properties of newly synthesized Cu2O/CuO-decorated TiO2/graphene oxide (GO) nanocomposites (NC) were analyzed aiming to obtain insight into their photocatalytic behavior and their various applications, including water remediation, self-cleaning surfaces, antibacterial materials, and electrochemical sensors. The physico-chemical methods of research were photoluminescence (PL), electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The solid samples evidenced an EPR signal that can be attributed to the oxygen-vacancy defects and copper ions in correlation with PL results. Free radicals generated before and after UV-Vis irradiation of powders and aqueous dispersions of Cu2O/CuO-decorated TiO2/GO nanocomposites were studied by EPR spectroscopy using two spin traps, DMPO (5,5-dimethyl-1-pyrroline-N-oxide) and CPH (1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine), to highlight the formation of hydroxyl and superoxide reactive oxygen species, respectively. The electrochemical characterization of the NC modified carbon-paste electrodes (CPE) was carried out by CV and DPV. As such, modified carbon-paste electrodes were prepared by mixing carbon paste with copper oxides-decorated TiO2/GO nanocomposites. We have shown that GO reduces the recombination process in TiO2 by immediate electron transfer from excited TiO2 to GO sheets. The results suggest that differences in the PL, respectively, EPR data and electrochemical behavior, are due to the different copper oxides and GO content, presenting new perspectives of materials functionalization.

Low Release Study of Cefotaxime by Functionalized Mesoporous Silica Nanomaterials.

As a third-generation ß-lactam antibiotic, cefotaxime shows a broad-spectrum with Gram-positive and Gram-negative bacteria activity and is included in WHO's essential drug list. In order to obtain new materials with sustained release properties, the present research focuses on the study of cefotaxime absorption and desorption from different functionalized mesoporous silica supports. The MCM-41-type nanostructured mesoporous silica support was synthesized by sol-gel technique using a tetraethyl orthosilicate (TEOS) route and cetyltrimethylammonium bromide (CTAB) as a surfactant, at room temperature and normal pressure. The obtained mesoporous material (MCM-41 class) was characterized through nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), N2 absorption-desorption (BET) and Fourier transform infrared spectroscopy (FT-IR), proving a good micro-structured homogeneity (SEM images), a high surface area (BET, 1029 m2/g) correlated with high silanolic activity (Q3/Q4 peak ratio from 29Si MAS-NMR), and an expected uniform hexagonal structure (2-3 nm, HRTEM). In order to non-destructively link the antibiotic compound on the solid phase, MCM-41 was further functionalized in two steps: with aminopropyl trimethoxysilane (APTMS) and glutaraldehyde (GA). Three cefotaxime-loaded materials were comparatively studied for low release capacity: the reference material with adsorbed cefotaxime on MCM-41, MCM-41/APS (aminopropyl silyl surface functionalization) adsorbed cefotaxime material, and APTMS-GA bounded MCM-41-cefotaxime material. The slow-release profiles were obtained by using an on-flow modified HPLC system. A significant improved release capacity was identified in the case of MCM-41/APS/GA-cefotaxime due to the covalent surface grafting of the biological active compound, recommending this class of materials as an effective carrier of bioactive compounds in wound dressing, anti-biofilm coatings, advanced drugs, and other related applications.

Bioactivity and Thermal Stability of Collagen-Chitosan Containing Lemongrass Essential Oil for Potential Medical Applications.

Bioactive collagen-chitosan-lemongrass (COL-CS-LG) membranes were prepared by casting method and analyzed for potential biomedical applications. For COL-CS-LG membranes, LG essential oil release, antioxidant properties, in vitro cytotoxicity and antimicrobial assessments were conducted, as well as free radical determination after gamma irradiation by chemiluminescence, and structural characteristics analysis through Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Differential Scanning Calorimetry (DSC). The evaluation of non-isothermal chemiluminescence after gamma radiation exposure to COL-CS-LG membranes revealed a slowing down of the oxidation process at temperatures exceeding 200 °C, in correlation with antioxidant activity. Antimicrobial properties and minimum inhibitory concentrations were found to be in correlation with cytotoxicity limits, offering the optimum composition for designing new biomaterials.

Bioactive Low Molecular Weight Keratin Hydrolysates for Improving Skin Wound Healing.

Keratin biomaterials with high molecular weights were intensively investigated but few are marketed due to complex methods of extraction and preparation and limited understanding of their influence on cells behavior. In this context the aim of this research was to elucidate decisive molecular factors for skin homeostasis restoration induced by two low molecular weight keratin hydrolysates extracted and conditioned through a simple and green method. Two keratin hydrolysates with molecular weights of 3758 and 12,400 Da were physico-chemically characterized and their structure was assessed by circular dichroism (CD) and FTIR spectroscopy in view of bioactive potential identification. Other investigations were focused on several molecular factors: α1, α2 and ß1 integrin mediated signals, cell cycle progression in pro-inflammatory conditions (TNFα/LPS stimulated keratinocytes and fibroblasts) and ICAM-1/VCAM-1 inhibition in human vascular endothelial cells. Flow cytometry techniques demonstrated a distinctive pattern of efficacy: keratin hydrolysates over-expressed α1 and α2 subunits, responsible for tight bounds between fibroblasts and collagen or laminin 1; both actives stimulated the epidermal turn-over and inhibited VCAM over-expression in pro-inflammatory conditions associated with bacterial infections. Our results offer mechanistic insights in wound healing signaling factors modulated by the two low molecular weight keratin hydrolysates which still preserve bioactive secondary structure.

Wool Keratin Hydrolysates for Bioactive Additives Preparation.

The aim of this paper was to select keratin hydrolysate with bioactive properties by using the enzymatic hydrolysis of wool. Different proteolytic enzymes such as Protamex, Esperase, and Valkerase were used to break keratin molecules in light of bioactive additive preparation. The enzymatic keratin hydrolysates were assessed in terms of the physico-chemical characteristics related to the content of dry substance, total nitrogen, keratin, ash, cysteic sulphur, and cysteine. The influence of enzymatic hydrolysis on molecular weight and amino acid composition was determined by gel permeation chromatography (GPC) and gas chromatography-mass spectrometry (GC-MS) analyses. Antimicrobial activity of keratin hydrolysates was analysed against Fusarium spp., a pathogenic fungus that can decrease the quality of plants. The bioactivity of enzymatic hydrolysates was tested on maize plants and allowed us to select the keratin hydrolysates processed with the Esperase and Valkerase enzymes. The ratio of organised structures of hydrolysate peptides was analysed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) deconvolution of the amide I band and may explain the difference in their bioactive behaviour. The most important modifications in the ATR spectra of maize leaves in correlation with the experimentally proven performance on maize development by plant length and chlorophyll index quantification were detailed. The potential of enzymatic hydrolysis to design additives with different bioactivity was shown in the case of plant growth stimulation.

Multifunctional Leather Surface Design by Using Carbon Nanotube-Based Composites.

This paper deals with original research in smart leather surface design for the development of multifunctional properties by using multi-walled carbon nanotube (MWCNT)-based nanocomposites. The conductive properties were demonstrated for both sheepskin and bovine leather surfaces for 0.5% MWCNTs in finishing nanocompositions with prospects for new material design intended for flexible electronics or multifunctional leathers. The photocatalytic properties of bovine leather surface treated with 0.5% MWCNTs were shown against an olive oil stain after visible light exposure and were attributed to reactive oxygen species generation and supported by contact angle measurements in dynamic conditions. The volatile organic compounds' decomposition and antibacterial tests confirmed the self-cleaning experimental conclusions. Ultraviolet protection factor had excellent values for leather surfaces treated with multi-walled carbon nanotube and the fastness resistance tests showed improved performance compared to control samples. Scanning electron microscopy with energy dispersive X-ray (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy analysis confirmed the influence of different leather surfaces on MWCNT dispersion with an effect on nanoparticle reactivity and efficiency in self-cleaning properties. Multifunctional leather surfaces were designed and demonstrated through MWCNT-based nanocomposite use under conventional finishing conditions.

New Nanofibers Based on Protein By-Products with Bioactive Potential for Tissue Engineering.

Concentrated collagen hydrolysate (HC10CC), rabbit collagen glue (RCG), and keratin hydrolysate (KH) were investigated in terms of their extraction from mammalian by-products and processing by electrospinning. The electrospun nanofibers were characterized by scanning electron microscopy coupled with the energy dispersive X-ray spectroscopy (SEM/EDS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC), and indentation tests. The cytotoxicity of the electrospun nanofibers was conducted on L929 fibroblast cells using MTT and LDH assays and cell morphology observations. The electrospun RCG and KH nanofibers morphology showed an average size of nanofibers ranging between 44 and 410 nm, while the electrospun HC10CC nanofibers exhibited higher sizes. The ATR-FTIR spectra performed both on extracted proteins and electrospun nanofibers showed that the triple helix structure of collagen is partially preserved. The results were in agreement with the circular dichroism analysis for protein extracts. Furthermore, the viscoelastic properties of electrospun KH nanofibers were superior to those of electrospun RCG nanofibers. Based on both in vitro quantitative and qualitative analysis, the electrospun nanofibers were not cytotoxic, inducing a healthy cellular response. The results of new electrospun protein-based nanofibers may be useful for further research on bioactive properties of these nanofibers for tissue engineering.

Bioactive Properties of Nanofibres Based on Concentrated Collagen Hydrolysate Loaded with Thyme and Oregano Essential Oils.

This research aimed to obtain biocompatible and antimicrobial nanofibres based on concentrated collagen hydrolysate loaded with thyme or oregano essential oils as a natural alternative to synthesis products. The essential oils were successfully incorporated using electrospinning process into collagen resulting nanofibres with diameter from 471 nm to 580 nm and porous structure. The presence of essential oils in collagen nanofibre mats was confirmed by Attenuated Total Reflectance -Fourier Transform Infrared Spectroscopy (ATR-FTIR), Ultraviolet-visible spectroscopy (UV-VIS) and antimicrobial activity. Scanning Electron Microscopy with Energy Dispersive Spectroscopy analyses allowed evaluating the morphology and constituent elements of the nanofibre networks. Microbiological tests performed against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans showed that the presence of essential oils supplemented the new collagen nanofibres with antimicrobial properties. The biocompatibility of collagen and collagen with essential oils was assessed by in vitro cultivation with NCTC clone 929 of fibroblastic cells and cell viability measurement. The results showed that the collagen and thyme or oregano oil composites have no cytotoxicity up to concentrations of 1000 µg·mL-1 and 500 µg mL-1, respectively. Optimization of electrospinning parameters has led to the obtaining of new collagen electrospun nanofibre mats loaded with essential oils with potential use for wound dressings, tissue engineering or protective clothing.

Hanes and Valea Vinului (Romania) closed mines Acid Mine Drainages (AMDs)--actual condition and passive treatment remediation proposal.

Acid Mine Drainages (AMDs) from Hanes and Valea Vinului (Romania) closed mines were considered for characterization and treatment using a local zeolitic volcanic tuff, ZVT, (Macicas, Cluj County, Romania). Water samples were collected from two locations, before and after discharging point in case of Hanes mine, and on three horizons in case of Valea Vinului mine. Physico-chemical (pH, total solid, heavy metal ions concentration) analyses showed that the environment is strongly affected by these AMD discharges even if the mines were closed years ago. Iron, manganese and zinc were the main pollutants identified in Hanes mine AMD, while zinc is the one mainly present in case of Valea Vinului AMD. A batch technique (no stirring) in which the ZVT was put in contact with the AMD sample was proposed as a passive remediation technique. ZVT successfully remove heavy metal ion from AMD. According to heavy metal ion concentrations, removal efficiencies are reaching 100%, varying as follows, Fe(2+)>Zn(2+)>Mn(2+). When the ZVT was compared with two cationic resins (strong, SAR and weak acid, WAR) the following series was depicted, SAR>ZVT>WAR.