Stanca (Colie) Maria
@certex.ro
Research and Development National Institute for Textiles and Leather, Division Leather and Footwear Research Institute
Scopus Publications
Scopus Publications
Maria Stanca, Elena Badea, Carmen Gaidau, Gabriela Elena Ionita, Noemi Proietti, Bogdan Lungu, Traian Zaharescu, and Ilaria Quaratesi
Elsevier BV
Carmen Gaidau, Maria Râpă, Gabriela Ionita, Ioana Rodica Stanculescu, Traian Zaharescu, Rodica-Roxana Constantinescu, Andrada Lazea-Stoyanova, and Maria Stanca
MDPI AG
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.
Gabriela Luta, Daniela Balan, Maria Stanca, Ovidiu Jerca, Stefana Jurcoane, Mihaela Niculescu, Carmen Gaidau, and Ioana Rodica Stanculescu
MDPI AG
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, β-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 β-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.
Stelica Cristea, Mihaela-Doina Niculescu, Alina Perisoara, Elena Ivan, Maria Stanca, Cosmin-Andrei Alexe, Bianca-Maria Tihauan, and Laura Olariu
MDPI AG
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).
Carmen Gaidau, Maria Râpă, Maria Stanca, Mariana-Luiza Tanase, Laura Olariu, Rodica Roxana Constantinescu, Andrada Lazea-Stoyanova, Cosmin-Andrei Alexe, and Madalina Tudorache
MDPI AG
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%).
Maria Stanca, Carmen Gaidau, Traian Zaharescu, George-Alin Balan, Iulia Matei, Aurica Precupas, Anca Ruxandra Leonties, and Gabriela Ionita
MDPI AG
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.
Daniela Balan, Gabriela Luţă, Maria Stanca, Ovidiu Jerca, Mihaela Niculescu, Carmen Gaidau, Stefana Jurcoane, and Antoaneta Mihalcea
MDPI AG
Protein hydrolysates are widely used in agricultural crops for improving plant nutrient uptake, growth, yield, and fruit quality. Tomato (Lycopersicon esculentum Mill.) is one of the most important vegetables consumed around the world both for its good taste and rich content in vitamins, minerals, lycopene, and β-carotene. The objective of the present study was to assess the effect of new stimulant products based on protein hydrolysates obtained from animal tissue by-products on tomato seedlings. Given the increased intake of amino acids, it is expected that this treatment will exert beneficial effects on the development of certain vigorous seedlings, representing the premise for obtaining superior tomato plants and the improvement of the production and quality of tomato fruit. Two variants of protein gels based on gelatin and keratin hydrolysates were obtained by processing bovine hide and wool and were used for periodical root applications on tomato seedlings cultivated in a greenhouse. During the experiment, the biometric characteristics of seedlings were measured weekly. The content of photosynthetic pigments, dry weight, sugars, and polyphenols were analyzed, and the antioxidant activity was assessed in the leaves. The research performed showed that applied biostimulant treatments increased the content of photosynthetic pigments by 10%, the content of sugars by 75%, and the content of polyphenols by 16% compared to the control untreated variant. Between the variants of protein gels tested, the best results were obtained by applying a mixture of bovine gelatin and keratin.
Constantin Voinitchi, Carmen Gaidau, Fanica Capatana Tudorie, Mihaela Niculescu, Maria Stanca, and Cosmin-Andrei Alexe
MDPI AG
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.
Daniela Bala, Iulia Matei, Gabriela Ionita, Dragos-Viorel Cosma, Marcela-Corina Rosu, Maria Stanca, Carmen Gaidau, Maria Baleanu, Marian Virgolici, and Ioana Stanculescu
MDPI AG
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.
Dan Eduard Mihaiescu, Daniela Istrati, Alina Moroșan, Maria Stanca, Bogdan Purcăreanu, Rodica Cristescu, Bogdan Ștefan Vasile, and Roxana Doina Trușca
MDPI AG
As a third-generation β-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.
Maria Râpă, Traian Zaharescu, Laura Mihaela Stefan, Carmen Gaidău, Ioana Stănculescu, Rodica Roxana Constantinescu, and Maria Stanca
MDPI AG
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.
Laura Olariu, Brindusa Georgiana Dumitriu, Carmen Gaidau, Maria Stanca, Luiza Mariana Tanase, Manuela Diana Ene, Ioana-Rodica Stanculescu, and Cristina Tablet
MDPI AG
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 β1 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.
Mariana Daniela Berechet, Demetra Simion, Maria Stanca, and Cosmin Andrei Alexe
INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania
The amino acid composition in the hydrolysates of fish proves to be a most promising source of protein. Two extracts from fish by-products (P1, from the head and fins of sturgeon and P2, from the cartilage of sturgeon head and fins) were obtained as liquids that were dried at 40°C. Liquid extracts were characterized physico-chemically (dry matter 3.86% and 4.25%, protein content 1.44% and 3.25%), and particle size (247nm, 94% and 4148nm, 65% majority populations for P1 and P2) and zeta potential (-27.4mV and -15.8mV) were measured. The smaller particle size for the P1 extract led to its choice for treatments applied in the growth of corn seeds. Four samples of concentrations of 0.5%, 1%, and 1.5% and control concentrations were experimented, each on 25 corn seeds, observing the growth of plants over a period of 13 days. A 13% higher increase of the corn plants was obtained in the case of the sample treated with 1.5% fish protein extract, P1. Throughout the experiments, the P1 sample with 1.5% fish protein extract had higher increases than the control sample. These results suggest that extracts from the head by-products of sturgeon fish could be used in agriculture as a nutrient in the growth of corn plants.
Demetra Simion, Carmen Gaidău, Mariana Daniela Berechet, Maria Stanca, Cosmin Alexe, and Gabriela Păun
INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania
The aim of the paper is to obtain new byproducts based on surfactants (gemini – polymethylene-α, ω-bis (N, N-dialkyl-N-deoxy-d-glucitolammonium iodides or bolaform – demecarium bromide) and protein hydrolysates (keratin and collagen) with micro and macro nutrients for applications in agriculture. A method was developed to include micro and macronutrients in keratin and collagen hydrolysates, in order to obtain new byproducts-bioemulsions (stable because of surfactants), with final goal of application as a new class of root fertilizers for cereals (e.g., corn). The newly obtained byproducts (bioemulsions based on surfactants) were characterized by: dynamic light scattering measurements, contact angle, optical microscopy and microbiological tests against fungal attack of Fusarium spp. and Botrytis cinerea. Better results were obtained for gemini surfactant based on sugar – polymethylene-α, ω-bis (N, N-dialkyl-N-deoxy-d-glucitolammonium iodides) due to the properties such as: biodegradability, nontoxicity and adherence to surfaces. The new fertilizer created in this research – bioemulsions based on surfactants, can support the general structure of the grains as well as the chlorophyll content, increasing the growth yield. The fertilizer is indicated for any type of crops and soils, with recommended use as additional fertilizer for plants (cereals) in the vegetation and growth phases, with a maximum need for nutrients.
Demetra Simion, Carmen Gaidau, Mariana Daniela Berechet, Maria Stanca, and Rodica Roxana Constantinescu
INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania
The interaction of turmeric powder with five surfactants (isopropyl oleate, diester of sucrose, polymethylene-α, ω-bis (N, N-dialkyl-N-deoxy-d-glucitolammonium iodides, bis [2-butyl (sodium bis-thioacetate) sodium dicarboxylate 1,10 decanediyl] ester, demecarium bromide) and obtaining nanoemulsions, has been investigated by spectroscopy, dynamic light scattering, optical microscopy and microbiological tests. The modeling encapsulation of turmeric powder in nanoemulsions was carried out taking into account the following parameters: the concentration and type of surfactants, the ratio between turmeric and surfactant, micellar critical concentration, speed and time of stirring, temperature, pH, average diameter of particles, zeta potential, conductivity. The known antibacterial and anti-inflammatory properties of turmeric can be improved by dispersing it in nanoemulsions resulting in better functional efficacy. The specific factors in designing nanoemulsion systems that affect the chemical stability of the encapsulated turmeric are discussed. In order to enhance turmeric effectiveness and improve bioavailability, surfactant assemblies as the colloidal carriers with desired properties have been largely used. The interaction takes place above the critical concentrations of the surfactants, when the encapsulation/ solubilization of turmeric in the micelles occurs. In our research we have elaborated a method for including turmeric in surfactants, following the preparation parameters modeling with the final aim of developing enhanced antibacterial properties.
Mariana Daniela Berechet, Demetra Simion, Rodica Roxana Constantinescu, Maria Stanca, and Cosmin Andrei Alexe
INCDTP - Leather and Footwear Research Institute (ICPI), Bucharest, Romania
Ocimum basilicum L. is an aromatic plant in the family Lamiaceae with bioactive properties used since ancient times in traditional medicine. The active ingredients of basil essential oil can be used in perfumes, pharmaceuticals, medicine, cosmetics or spices. In this study, the essential oil of basil was obtained by hydrodistillation in the Clevenger continuous extractor. It was characterized by GC-MS and 53 constituent compounds were identified. The majority compounds were highlighted: linalool, 64,569%, p-allyl anisol, 5,163%, Eucalyptol, 3,745%, α-Cadinene, 3,510%. Kovats indices were calculated and FT-IR analysis was performed to confirm the specific constituent compounds. The essential oil of basil was microbiologically analyzed against Escherichia coli (ATCC 10536) Gram-negative bacteria and against Staphylococcus aureus (ATCC 6538) Gram-positive bacteria by diffusometric working method. Antibacterial activity was determined by measuring the diameter of the inhibition zone around the samples. Samples of filter paper and cotton fabric were used to simulate shoe lining and bandages. Basil essential oil has resistance against the tested strains, observing the increase of the inhibition zone with the increase of the amount of essential oil used in treatments (20 μL, 30 μL, 50 μL). The results showed that Ocimum basilicum L. may be a good candidate as a plant-derived antibacterial agent for medical footwear, wound dressings and other medical applications.
Demetra Simion, Carmen Gaidău, Gabriela Păun, Maria Stanca, and Daniela Berechet
Leather and Footwear Research Institute (INCDTP-ICPI)
New bioemulsions structured like “networks” were created by innovative technologies based on: elastin/zinc hydroxide/ (bolaamphiphiles mixture: bis [2-butyl (sodium bis-thioacetate) sodium dicarboxylate 1,10 decanediyl ester] and/or sucrose diester)/ acetic acid/water, for improved surface properties development with applications in leather industry. We used in this research two “bolaamphiphiles”. Bolaamphiphilic molecules contain a hydrophobic skeleton (e.g., one, two, or three alkyl chains, a steroid, or a porphyrin) and two water-soluble groups on both ends. The interaction of surfactants with biopolymers in aqueous medium results in the formation of different association structures. There are various morphologies of biopolymer-surfactant association complexes depending on the molecular structure of the biopolymer and surfactant, on the nature of interaction forces between solvents and surfactant or biopolymer. The innovation consists in the technologies for obtaining novel micro and nanostructured bioemulsions, and the compatibilisation with film forming polymers for leather surface finishing. Elastin/zinc hydroxide micro and nanocomposites have been stabilized with bolaamphiphilic surfactants mixture: bis [2-butyl (sodium bis-thioacetate) sodium dicarboxylate 1,10 decanediyl ester and sucrose diester in a 1:1 acetic acid/water ratio, to increase the uniformity of nanocomposites. Micro and nanostructured composites like “networks” developed as a result of biopolymer-surfactants interactions for elastin/zinc hydroxide/surfactants mixture couple in acetic acid/water system are reported by SEM microscopy and DLS analysis. A special class of micro and nanoarchitectures is represented by structures organized as “network” assemblies. The novel micro and nanocomposites can provide the hybrid film with increased resistance to rubbing and water, and to deformation. Environmentally-friendly substrates with smart multifunctional features can be obtained for various applications.
Carmen Gaidau, Maria Stanca, Mihaela-Doina Niculescu, Cosmin-Andrei Alexe, Marius Becheritu, Roxana Horoias, Cristian Cioineag, Maria Râpă, and Ioana Rodica Stanculescu
MDPI AG
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.
Maria Stanca, Carmen Gaidau, Cosmin-Andrei Alexe, Ioana Stanculescu, Silvana Vasilca, Andreea Matei, Demetra Simion, and Roxana-Rodica Constantinescu
MDPI AG
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.
Carmen Gaidau, Ioana Rodica Stanculescu, Maria Stanca, Mihalis Cutrubinis, Laura Trandafir, Mioara Alexandru, and Cosmin-Andrei Alexe
Elsevier BV
Abstract In this work bovine hides were treated with 25, 35 and 50 kGy in a Gamma Chamber 5000 self-shielded research irradiator and the influence of radiation dose on hide microbiological load, collagen crosslinking, interfibrillary substances solubility by shrinkage temperature and soluble nitrogen was evaluated in comparison with crude hide and sodium chloride treated hides (raw hides). Pilot level experiments were performed on large hide quantities in a SVST-Co-60/B Multipurpose Gamma Industrial Irradiator at 25 kGy as well as on semi processed leathers e.g. wet-blue, split wet-blue and crust. The evaluation of shrinkage temperature, microbiological load and physico-chemical and mechanical characteristics of gamma irradiated leathers showed that small modifications are induced by 25 kGy gamma irradiation. The scanning electron microscopy images of leather cross sections and Fourier Transform Infrared spectra confirmed minimum structural modifications at molecular level and not at microscopic level. Gamma irradiation allows conservation of high quantities of hides and leathers with impact on final product quality improvement, substantial infection reduction in abattoirs, raw material warehouses or tanneries shops, reduction of total dissolved solids by 40% and of chloride concentration by 78% from wastewaters.
L. Septar, C. Moale, C. Gavăt, V.A. Opriță, I. Caplan, M. Stanca, and G. Lămureanu
International Society for Horticultural Science (ISHS)
Ecaterina Matei, Carmen Gaidau, Maria Râpă, Laura Mihaela Stefan, Lia-Mara Ditu, Andra Mihaela Predescu, Maria Stanca, Mircea Cristian Pantilimon, Mariana Daniela Berechet, Cristian Predescu,et al.
MDPI AG
In this study, sodium alginate film (Alg) was coated with electrospun collagen glue (Col) extracted from rabbit skin waste, loaded with different commercial antimicrobial agents (chitosan, AG425K and ZnONPs) and investigated in terms of morphological, structural and biological properties. The coated nanostructures were characterized using scanning electron microscopy coupled with the energy-dispersive X-ray (SEM/EDS), Attenuated Total Reflectance Fourier-Transform Infrared spectroscopy (ATR FT-IR), and Atomic Force Microscopy (AFM) tests. The cytotoxicity was investigated on murine L929 fibroblasts using 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide salt (MTT) and lactate dehydrogenase (LDH) assays. Microbiological tests were performed against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Candida albicans ATCC 27853 standard strains. In vitro cell culture tests showed a good cytocompatibility of the coated nanostructured systems, except the sample loaded with ZnONPs, which exhibited a highly cytotoxic effect. Alg-Col-ZnONPs nanostructure inhibited the growth and multiplication of the Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 bacterial strains. The results of new coated nanostructures may be useful for the development of sustainable biomaterials in a circular economy, with bioactive properties for medical wound dressings.
C.A. Alexe, C. Gaidau, M. Stanca, A. Radu, M. Stroe, M. Baibarac, G. Mateescu, A. Mateescu, and I.R. Stanculescu
Elsevier BV