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1.
Trajnostni biokompozitni materiali iz naravnih polimerov in njihova neporušna karakterizacija z optotermičnimi tehnikami
Mladen Franko, other performed works

Abstract: Predstavljene so osnove zelene sinteze novih biokompozitnih materialov iz kombinacij celuloze s hitosanom ali keratinom in sporopoleninom ter njihove protimikrobne lastnosti in adsorpcijske sposobnosti za čiščenje vode. Pomembna lastnost biokompozitov z vidika njihove uporabnosti je tudi poroznost, ki jo lahko določamo neporušno in nekontaktno s tehniko optotermičnega odlkona. Ta omogoča določevanje toplotne difuzivnosti materialov ter preko nje poroznosti, kot tudi globinske porazdelitve v material vgrajenih snovi, ki izboljšujejo njegove lastnosti.
Keywords: Biokompoziti, celuloza, hitosan, keratin sporopolenin, toplotna difuzivnost, poroznost, optotermična spektrometrija
Published in RUNG: 11.05.2023; Views: 1688; Downloads: 0
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2.
Synthesis of bio-composite sustainable materials and their applications in environmental technology
Mladen Franko, published scientific conference contribution abstract (invited lecture)

Abstract: Organic wastes such as wood, hair, feathers, exoskeletons of crustaceans and molluscs or even water melon rind represent some examples of valuable and abundant sources of natural polymers such as cellulose, keratin and chitin, which were already extensively exploited for preparation of novel bio-composite materials. Application of green chemistry approaches for their synthesis makes such bio-composites really sustainable materials with several interesting properties for different applications, including those in environmental technology. In this review, synthesis of novel bio-composites based on cellulose (CEL), chitosan (CS - chemically modified chitin) or keratin (KER) and their potential for application in environmental technology will be presented. The synthesis is based on dissolution of bio-polymers in ionic liquids. This is the crucial step in the synthesis of such materials, which at the same time makes the process completely recyclable with regard to the solvents. The tensile strength is regulated by the proportion of CEL in the material, while higher proportions of CS were shown to add to the adsorptive and antimicrobial activity of the material [1]. Antimicrobial activity was also observed for CEL:KER materials and was further improved by decorating the bio-composites with silver or gold nanoparticles [2]. Our research has shown high potential for application of synthesised bio-composites in environmental technologies including removal of toxins or killing of pathogens in water. It was demonstrated that CEL:CS composites can remove up to 96 mg of microcystin per gram of composite, which is almost 5 times higher than best known adsorbent for microcystin [1]. On the other hand CEL:KER composites with incorporated Ag0 nanoparticles have shown up to 6 logs of reduction in the number of bacteria (99.9999% growth reduction) of bacteria such as E. coli which is a frequently encountered pathogen in wastewaters [2]. [1] TRAN, C. D., DURI, S., DELNERI, A., FRANKO, M. (2013), Chitosan-cellulose composite materials: preparation, characterization and application for removal of microcystin, Journal of hazardous materials. 252/253, p 355-366 [2] TRAN, C. D., PROSENC, F., FRANKO, M., BENZI, G. (2016, One-pot synthesis of biocompatible silver nanoparticle composites from cellulose and keratin: characterization and antimicrobial activity, ACS applied materials & interfaces. 8, p 34791-34801
Keywords: Trajnostni materiali, biokompoziti, celuloza, hitosan, keratin, sporopolenin, mikrocistin
Published in RUNG: 06.12.2022; Views: 2739; Downloads: 0
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3.
Facile synthesis, structure, biocompatibility and antimicrobial property of gold nanoparticle composites from cellulose and keratin
Chieu D. Tran, Franja Prosenc, Mladen Franko, 2018, original scientific article

Abstract: A novel, one-pot method was developed to synthesize gold nanoparticle composite from cellulose (CEL), wool keratin (KER) and chloroauric acid. Two ionic liquids, butylmethylimmidazolium chloride and ethylmethylimmidazolium bis(trifluoromethylsulfonyl)imide were used to dissolve CEL, KER and HAuCl4. X-ray diffraction and X-ray photoelectron results show that Au3+ was completely reduced to Au0NPs with size of (5.5 ± 1) nm directly in the composite with NaBH4. Spectroscopy and imaging results indicate that CEL and KER remained chemically intact and were homogeneously distributed in the com- posites with Au0NPs. Encapsulating Au0NPs into [CEL+KER] composite made the composite fully biocom- patible and their bactericidal capabilities were increased by the antibacterial activity of Au0NPs. Specifically, the [CEL+KER+Au0NPs] composite exhibited up to 97% and 98% reduction in growth of antibi- otic resistant bacteria such as vancomycin resistant Enterococcus faecalis and methicillin resistant Staphylococcus aureus, and was not cytotoxic to human fibroblasts. While [CEL+KER] composite is known to possess some antibacterial activity, the enhanced antibacterial observed here was due solely to added Au0NPs. These results together with our previous finding that [CEL+KER] composites can be used for con- trolled delivery of drugs clearly indicate that the [CEL+KER+Au0NPs] composites possess all required properties for successful use as dressing to treat chronic ulcerous infected wounds.
Keywords: Ionic liquid Green Sustainable Polysaccharide Keratin Wound dressing Gold nanoparticles Antibiotic-resistant bacteria
Published in RUNG: 27.09.2017; Views: 4645; Downloads: 0
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4.
TOXIC CHEMICALS AND TOXINS IN THE ENVIRONMENT AND TECHNOLOGIES FOR THEIR DETECTION AND REMOVAL
Mladen Franko, invited lecture at foreign university

Keywords: Microcystin, MRI contrast agents, pesticides, biocomposites, keratin, chitosan
Published in RUNG: 01.03.2017; Views: 5162; Downloads: 0
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5.
One-pot synthesis of biocompatible silver nanoparticle composites from cellulose and keratin: characterization and antimicrobial activity
Chieu Ding Tran, Franja Prosenc, Mladen Franko, Gerald Benzi, 2016, original scientific article

Abstract: A novel, simple method was developed to synthesize biocompatible composites containing 50% cellulose (CEL) and 50% keratin (KER) and silver in the form of either ionic (Ag+) or Ag0 nanoparticle (Ag+NPs or Ag0NPs). In this method, butylmethylimmidazolium chloride ([BMIm+Cl-]), a simple ionic liquid, was used as the sole solvent and silver chloride was added to the [BMIm+Cl-] solution of [CEL+KER] during the dissolution process. The silver in the composites can be maintained as ionic silver (Ag+) or completely converted to metallic silver (Ag0) by reducing it with NaBH4. Results of spectroscopy (Fourier-transform infrared (FTIR), X-ray diffraction (XRD)) and imaging (scanning electron microscope (SEM)) measurements confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. Powder X-ray diffraction (XRD) and SEM results show that the silver in the [CEL+KER+Ag+] and [CEL+KER+Ag0] composites is homogeneously distributed throughout the composites in either Ag+ (in the form of Ag2O nanoparticles (NPs)) or Ag0NPs form with size of (9 ± 1) nm or (27 ± 2) nm, respectively. Both composites were found to exhibit excellent antibacterial activity against many bacteria including Escherichia coli, Staphylococus aureus, Pseudomonas aeruginosa, methicillin resistant Staphylococus aureus (MRSA), vancomycin resistant Enterococus faecalis (VRE). The antibacterial activity of both composites increases with the Ag+ or Ag0 content in the composites. More importantly, for the same bacteria and the same silver content, [CEL+KER+Ag0] composite exhibits relatively greater antimicrobial activity against bacteria compared to the corresponding [CEL+KER+Ag+] composite. Experimental results confirm that there was hardly any Ag0NPs release from the [CEL+KER+Ag0NPs] composite, and hence its antimicrobial activity and biocompatibility is due, not to any released Ag0NPs but rather entirely to the Ag0NPs embedded in the composite. Both Ag2ONPs or Ag0NPs were found to be toxic to human fibroblasts at higher concentration (>0.72 mmol), and that for the same silver content, [CEL+KER+Ag2ONPs] composite is relatively more toxic than [CEL+KER+Ag0NPs] composite. As expected, by lowering the Ag0NPs concentration to 0.48 mmol or less, the [CEL+KER+Ag0NPs] composite can be made biocompatible while still retaining its antimicrobial activity against bacteria such are E. coli, S. aureus, P. aeruginosa, MRSA, VRE. These results together with our previous finding that [CEL+KER] composites can be used for controlled delivery of drugs such as ciprofloxacin clearly indicate that the [CEL+KER+Ag0NPs] composite possess all required properties for successfully used as high performance dressing to treat chronic ulcerous infected wounds.
Keywords: Celulose, Keratin, Cmposites, Biocompatible, Ag nanoparticles, one-pot synthesis, Antibacterial, Antiviral
Published in RUNG: 28.11.2016; Views: 5376; Downloads: 0
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6.
Synthesis, Structure and Antimicrobial Property of Green Composites from Cellulose, Wool, Hair and Chicken Feather
Chieu Tran, Franja Prosenc, Mladen Franko, Gerald Benzi, 2016, original scientific article

Abstract: Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simple one-step process in which butylmethylimidazolium chloride (BMIm+Cl-), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm+Cl-] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of KER in wool, hair and feather produced pronounced differences in the conformation of their corresponding composites with wool has the highest α-helix content and feather has the lowest content. These results correlate well with mechanical and antimicrobial properties of the composites. Specifically, adding CEL into KER substantially improves mechanical strength of [CEL+KER] composites made from all three different sources, wool, hair and chicken feathers (i.e., [CEL+wool], [CEL+hair] and [CEL+feather]. Since mechanical strength is due to CEL, and CEL has only random structure, [CEL+feather] has, expectedly, the strongest mechanical property because feather has the lowest content of α-helix. Conversely, [CEL+wool] composite has the weakest mechanical strength because wool has the highest α-helix content. All three composites exhibit antibacterial activity against methicillin resistant S. aureus (MRSA). The antibacterial property is due not to CEL but to the protein and strongly depends on the type of the keratin, namely, the bactericidal effect is strongest for feather and weakest for wool. These results together with our previous finding that [CEL+KER] composites can control release of drug such as ciprofloxacin clearly indicate that these composites can potentially be used as wound dressing.
Keywords: Green synthesis, Ionic liquid, Keratin, Antibacteria, Wound dressing
Published in RUNG: 08.06.2016; Views: 4770; Downloads: 0
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