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1.
Polymers (Basel) ; 16(4)2024 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-38399844

RESUMO

(1) Background: A widespread problem in oral health is cavities produced by cariogenic bacteria that consume fermentable carbohydrates and lower pH to 5.5-6.5, thus extracting Ca2+ and phosphate ions (PO43-) from teeth. Dental restorative materials based on polymers are used to fill the gaps in damaged teeth, but their properties are different from those of dental enamel. Therefore, a question is raised about the similarity between dental composites and natural teeth in terms of density and hardness. (2) Methods: We have used Raman spectroscopy and density and microhardness measurements to compare physical characteristics of several restorative dental composites at different polymerization intervals. (3) Results: XRVHerculite®, Optishade®, and VertiseFlow® showed the very different characteristics of the physical properties following four polymerization intervals. Of the three composites, OptiShade showed the highest polymerization rate. (4) Conclusions: Only fully polymerized composites can be used in teeth restoring, because incomplete polymerization would result in cracks, pitting, and lead finally to failure.

2.
Foods ; 12(15)2023 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-37569178

RESUMO

We successfully prepared a non-enzymatic sensor based on a graphene-thiophene composite for histamine detection. The self-assembling properties of the thiophene onto Au support and the high electrical conductivity of graphene encouraged the choice of this type of composite. The composite was deposited via electrochemical polymerization onto the Au layer of a screen-printed microelectrode. The electropolymerization and electrochemical detection of histamine were both achieved by cyclic voltammetry. Two types of electrolytes were used for the electrochemical detection: (a) phosphate buffer solution (PBS), which showed low-intensity redox peaks for histamine; and (b) trichloroacetic acid (TCA) 0.01 M, which showed improved results over PBS and did not damage the microelectrode. For the concentration range of 100-200 mg/kg, the sensor shows a linear regression pattern for the oxidation peak fitted on the equation Ipa = 123.412 + 0.49933 ×x, with R2 = 0.94178. The lowest limit of detection was calculated to be 13.8 mg/kg and the limit of quantification was calculated at 46 mg/kg. These results are important since by monitoring the amount of histamine in a food product, early onset of spoilage can be easily detected, thus reducing foodborne poisoning and food waste (by recycling products that are still edible).

3.
Artigo em Inglês | MEDLINE | ID: mdl-36981696

RESUMO

(1) Background: In oral surgery, bone regeneration is achieved through various types of bone grafts or bone substitutes and its success is usually analyzed by micro-computed tomography and histomorphometry. The aim of this study was to evaluate the usefulness of Raman spectroscopy as an alternative to other techniques for bone quality evaluation during a standard oral surgery procedure. (2) Methods: The preliminary evaluation of bone augmentation during maxillary sinus floor elevation oral surgery was performed by Raman spectroscopy for several (five) patients during and after the surgery and the results were compared with postoperative data from histomorphometry, EDX and SEM analysis. (3) Results: After analyzing all the results for the bone samples according to the four methods (Raman, EDX, SEM and Histology) that were used in our study, the obtained result of the investigation provided a good augmentation process for three of the patients and partly successful augmentation process for two of the patients. The primary evaluation using Raman spectroscopy (in vivo and ex vivo investigation) was confirmed by histological results, thus having a first step for validation of Raman as a new method of imaging for dentistry. (4) Conclusions: Our results show that Raman spectroscopy could provide fast and reliable insight on bone condition during augmentation of the maxillary sinus floor. We emphasize the advantages and drawbacks of the proposed techniques as its accuracy could increase by performing larger size clinical trials. Using the Raman mapping, the method can serve as an alternative to histology.


Assuntos
Levantamento do Assoalho do Seio Maxilar , Humanos , Levantamento do Assoalho do Seio Maxilar/métodos , Seio Maxilar/diagnóstico por imagem , Seio Maxilar/cirurgia , Microtomografia por Raio-X , Análise Espectral Raman , Transplante Ósseo/métodos
4.
Diagnostics (Basel) ; 14(1)2023 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-38201375

RESUMO

(1) Background: The intent of this survey was to investigate the quality of the alveolar bone by revealing the different phases for calcified tissues independent of the medical history of the patient in relation to periodontal disease by means of Raman spectroscopy and then to correlate the results by suggesting a possible mechanism for the medical impairment; (2) Methods: The investigation was mainly based on Raman spectroscopy that was performed in vivo during surgery for the selected group of patients. The targeted peaks for the Raman spectra were according to the reference compounds (e.g., calcium phosphates, other phosphates); (3) Results: The variation in the intensity of the spectrum correlated to the specific bone constituents' concentrations highlights the bone quality, while some compounds (such as pyrophosphate, PPi) are strongly related to the patient's medical status, and they provide information regarding a physiological process that occurred in the calcified tissues. Moreover, bone sample fluorescence is related to the collagen (Col) content, enabling a complete evaluation of bone quality, revealing the importance of collagen matrix acting as a load-bearing element for Calcium phosphate (CaP) deposition during the complex bone mineralization process; (4) Conclusions: We highlight that Raman spectroscopy can be considered a viable investigative method for in vivo and rapid bone quality valuation through oral health monitoring.

5.
iScience ; 26(12): 108563, 2023 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-38162018

RESUMO

We investigate the influence of the seed of measurement on the performance of a Szilard engine based on a two-mode Gaussian state evolving in a noisy channel. Quantum work is extracted by performing a positive operator-valued measurement (POVM) on one of the two modes, after which this mode reaches equilibrium with the environment. As the seed of measurement, we use a single-mode squeezed thermal state. We employ the Markovian Kossakowski-Lindblad master equation to determine the evolution in time of the considered open system and the quantum work is defined based on the Rényi entropy of order 2. We show that the extracted quantum work and information-work efficiency strongly depend on the characteristic parameters of the system (frequency, average thermal photons number, and squeezing), the noisy channel (temperature and squeezing of the bath), and the seed of measurement (average thermal photons number and strength of the measurement).

6.
Diagnostics (Basel) ; 12(11)2022 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-36359436

RESUMO

In this work, we study the sensing properties of multi-layer graphene combined with pyrrole in order to elaborate low-cost, high-sensitive material for cortisol detection. Graphene nanoplatelets and pyrrole were dispersed in a solution containing 1M HNO3 by using a powerful ultrasound probe for 10 min, then centrifuged for 30 min at 4000 rpm; polymerization was performed by cyclic voltammetry. The graphene-pyrrole composite was tested to ultra-low levels of cortisol in artificial saliva, consistent to the levels excreted in human salivary samples. The composite was further investigated by Raman spectroscopy and we modeled the interaction between the sensitive layer and cortisol using MarvinBeans software. It shows a good sensitivity for salivary values of cortisol cyclic voltammetry being able to detect a level down to 0.5 ng/mL cortisol.

7.
Diagnostics (Basel) ; 12(11)2022 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-36359522

RESUMO

In this study, we explore the "why?", and "how?", monitoring the pH of the fetal scalp is used, and show its limitations. In addition, we review the development of new devices based on the modern physics and nanomaterials serving this topic. Most of the works we found in our search have focused on improving the prognostic of fetal heart rate monitoring, because it is the "golden standard" in determining fetal distress. Although the best-known screening method, it can only provide limited information about the actual status of the fetus. The best predictive assessment, with the highest reproducibility, states that a normal fetal heart rate is indicative of a healthy baby. However, its excellent sensitivity is much reduced when identifying the actual "distress". This is when second-line monitoring methods come into play to guide the diagnostics and direct the obstetrician towards an action plan. Although a historic method, fetal scalp pH sampling is still under review as to its efficiency and place in the current obstetrics. Continuous surveillance of the fetal parameters is important, especially for the fetuses undergoing intrauterine growth restricted (IUGR). Since fetal scalp blood sampling is still under research and is a randomized controlled trial, which compares the relevance of pH and lactates to the obstetrical situation, the maternal-fetal medicine could greatly benefit from the introduction of engineered nanomedicines to the field.

8.
Diagnostics (Basel) ; 12(11)2022 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-36428822

RESUMO

Gout is a metabolic condition, common to animals and humans, issuing from the excessive accumulation of end products of proteins degradation. In this study, histopathological and cytological examinations, combined with Raman spectroscopy, have been performed to investigate tissue samples from reptiles, chickens, and humans, presenting lesions produced by uric acid accumulation. As a result of classic processing and staining techniques commonly used in the anatomopathological diagnosis, uric acid crystals lose their structural characteristics, thus making difficult a precise diagnostic. Therefore, complementary diagnostic methods, such as Raman spectroscopy, are needed. This study compares from several perspectives the above mentioned diagnostic methods, concluding that Raman spectroscopy provides highlights in the diagnosis of gout in humans and animals, also adding useful information to differential diagnosis of lesions.

9.
Diagnostics (Basel) ; 12(8)2022 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-36010343

RESUMO

(1) Background: The treatment of dental cavities and restoration of tooth shape requires specialized materials with specific clinical properties, including being easy to model, light-cured, having a natural color, reduced shrinkage, a hardness similar to hydroxyapatite, and no leakage. The dimensional stability of resin composite materials is affected by polymerization shrinkage, degree of conversion (number of π carbon bonds converted into σ ones), thermal contraction and expansion, and interactions with an aqueous environment. (2) Methods: The materials used in our investigation were two composite resins with similar polymer matrices, but different filler (micro/nano filler). To evaluate the properties of samples, we employed the pycnometer technique (pycnometer from Paul Marienfeld Gmbh, Lauda-Königshofen, Germany), RAMAN spectroscopy technique (MiniRam Equipment from B&W Tek Inc., Plainsboro Township, NJ, USA; 785 nm laser source), SEM and EDX (FEI Inspect S.). (3) Results: The size of the filler plays an important role in the polymerization: for the pycnometric results, the larger particle filler (Sample 1) seems to undergo a rapid polymerization during the 45 s curing, while the nanoparticle filer (Sample 2) needs additional curing time to fully polymerize. This is related to a much larger porosity, as proved by SEM images. The lower degree of conversion, as obtained by Raman spectroscopy, in the same geometry means that the same volume is probed for both samples, but Sample 1 is more porous, which means less amount of polymer is probed for Sample 1. (4) Conclusions: For the two composites, we obtained a degree of conversion of 59% for Sample 1 and 93% for Sample 2, after 45 s of curing.

10.
Diagnostics (Basel) ; 12(3)2022 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-35328277

RESUMO

The aim of this study was to evaluate the quality of the bone, revealing the different phases for calcified tissues independent of the medical history of the patient in relation to periodontitis by means of in vivo Raman spectroscopy. Raman spectroscopy measurements were performed in vivo during surgery and then ex vivo for the harvested bone samples for the whole group of patients (ten patients). The specific peaks for the Raman spectrum were traced for reference compounds (e.g., calcium phosphates) and bone samples. The variation in the intensity of the spectrum in relation to the specific bone constituents' concentrations reflects the bone quality and can be strongly related with patient medical status (before dental surgery and after a healing period). Moreover, bone sample fluorescence is related to collagen content, enabling a complete evaluation of bone quality including a "quasi-quantification" of the healing process similar to the bone augmentation procedure. A complete evaluation of the processed spectra offers quantitative/qualitative information on the condition of the bone tissue. We conclude that Raman spectroscopy can be considered a viable investigation method for an in vivo and quick bone quality assessment during oral and periodontal surgery.

11.
Materials (Basel) ; 15(5)2022 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-35268873

RESUMO

Phosphate and tellurite glasses can be used in optics, optoelectronics, magneto-optics, and nuclear and medical fields. Two series of phosphate-tellurite glasses, (50-x)ZnO-10Al2O3-40P2O5-xTeO2 and (40-x)Li2O-10Al2O3-5TiO2-45P2O5-xTeO2 (x = 5, 10), were synthesized by a non-conventional wet-route, and the mechanical properties as key performance measures for their application in optoelectronics were investigated. X-ray Diffraction (XRD) measurements revealed the vitreous nature of the investigated materials. Instrumented indentation tests allowed the calculation of hardness (H) and Young's modulus (E) using the Oliver and Pharr model. The influence of increasing the TeO2 content, as well as the substitution of ZnO by Li2O-TiO2, on the variation of hardness, Young's modulus, penetration depth (PD), and fracture toughness (FT) was evaluated in both series. As a general trend, there is a decrease in the hardness and Young's modulus with increasing penetration depth. The addition of Li2O and TiO2 instead of ZnO leads to improved hardness and elastic modulus values. Regarding the H/E ratio, it was found that the samples with lower TeO2 content should be significantly more crack-resistant compared to the higher TeO2 content samples. The H3/E2 ratio, being lower than 0.01, revealed a poor resistance of these glasses to plastic deformation. At the same time, a decrease of the fracture toughness with increasing TeO2 content was noticed for each glass series. Based on dilatometry measurements, the thermal expansion coefficient as well as the characteristic temperatures of the glasses were measured. Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray analysis (FESEM-EDX) revealed a uniform distribution of the elements in the bulk samples. The mechanical properties of these vitreous materials are important in relation to their application as magneto-optical Faraday rotators in laser cavities.

12.
Diagnostics (Basel) ; 11(12)2021 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-34943587

RESUMO

OBJECTIVE: The aim of this study is to propose a standardized management of care for patients diagnosed with cesarean scar pregnancy (CSP). There are two types of CSP: Type 1 (on the scar) vs. type 2 (in the niche). To date there is no international standard to predict the extent of invasion or the optimal management of CSP. MATERIALS AND METHODS: We used intramuscular methotrexate injection followed by uterine artery embolization combined with suction evacuation as a conservative approach for the treatment of seven patients diagnosed with CSP. Our inclusion criteria, to be satisfied simultaneously, were established as follows: (1) patients with CSP; (2) early gestational age ≤ 9 weeks, and (3) written consent of the proposed treatment of the patient. RESULTS: This course of treatment produced a positive outcome in all cases. We did not have any complications (e.g., emergency hysterectomy, perforation of the uterine cavity, severe hemorrhage, or endometritis) during the procedures or in the follow-up. The most important predictors of successful management are early diagnosis of CSP and orientation of the invasive trophoblast opposite to the scar. CONCLUSIONS: The main finding from this series of cases is that associating systemic methotrexate and uterine artery embolization provides efficient and low-risk management of CSP. This treatment regime is adequate for both types of CSPs. We consider that early localization diagnosis of pregnancy following a cesarean delivery is mandatory for CSP morbidity prevention.

13.
Nanomaterials (Basel) ; 10(9)2020 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-32962165

RESUMO

This work investigates the structural, magnetic and magneto-optical properties of a new zinc phosphate-tellurite glass belonging to the 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing the starting reagents followed by suitable melting-stirring-quenching-annealing steps. Specific parameters such as density, average molecular mass, molar volume, oxygen packaging density, refractive index, molar refractivity, electronic polarizability, reflection loss, optical transmission, band gap and optical basicity have been reported together with thermal, magnetic and magneto-optical characteristics. Absorption bands appear in the blue and red visible region, while over 600 nm the glass becomes more transparent. FTIR and Raman spectra evidenced phosphate-tellurite vibration modes proving the P2O5 and TeO2 network forming role. Magnetic measurements reveal the diamagnetic character of the Te-doped glass with an additional weak ferromagnetic signal, specific to diluted ferromagnetic oxides. Positive Faraday rotation angle with monotonous decreasing value at increasing wavelength was evidenced from magneto-optical measurements. The final product is a composite material comprising of a non-crystalline vitreous phase and Te-based nanoclusters accompanied by oxygen vacancies. The metallic-like Te colloids are responsible for the dark reddish color of the glass whereas the accompanying oxygen vacancies might be responsible for the weak ferromagnetic signal persisting up to room temperature.

14.
Food Sci Technol Int ; 26(2): 113-122, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31461367

RESUMO

In this study, the quality of the local Romanian butters was investigated using the classical pycnometer and optic microscopy methods, combined with Raman spectroscopy. We used a pool of 10 samples with different characteristics, and analyzed them by the three aforementioned methods. Pycnometric measurements showed a direct correlation between the fat content and the density values of the samples. Raman spectroscopy validated the results from the pycnometric measurements and the optical microscopy and indicated several other properties, such as protein content, hydration, saturation level of the polycarbonate chains, as well as the total cis isomer content and the type of arrangement preferred by the aliphatic chains (polymorphic transition). The methods employed in the present study have a strong potential to become analytical tools for the food industry and food safety agencies in order to assess the quality of butters and margarines, in a fast and cost-effective manner.


Assuntos
Manteiga/análise , Análise Espectral Raman , Gorduras na Dieta/análise , Análise de Alimentos , Margarina/análise , Microscopia , Tamanho da Partícula , Análise de Componente Principal
15.
Mater Sci Eng C Mater Biol Appl ; 101: 120-137, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31029305

RESUMO

The paper describes an innovative bio-design of some hybrid nanoarchitectures containing bioartificial membranes and silver nanoparticles phytogenerated by using a natural extract Caryophyllus aromaticus (cloves) that contains many bioactive compounds. Two kinds of liposomes with and without chlorophyll a (Chla) obtained through thin film hydration method were used to achieve bio-green-generated hybrids by a simple, cost effective bottom-up approach. The characteristic peaks of CE-nAg monitored by UV-Vis absorption have firstly demonstrated the biohybrids formation. The slightly blue shift and fluorescence quenching observed by fluorescence emission spectra highlighted the formation of hybrid systems by biointeraction between lipid vesicles and silver nanoparticles. The incorporation of silver nanoparticles in lipid vesicles resulted in significant changes of FT-IR spectra of liposomes, indicating a reorganization of biomimetic membranes. All the microscopic methods (SEM, AFM and TEM) confirmed the biosynthesis of "green" AgNPs together with associated biohybrids, their spherical and quasi-spherical shapes with nano-scaled size. By TEM assay it was shown that CE-nAg are surrounded by petal like cloud structures that consist of biopolymers like proteins or polysaccharides and other phytochemicals arising from clove extract. EDS spectra confirmed the formation of phyto-nanoAg and also the presence of silver in the biohybrids. In addition, Selected Area Electron Diffraction showed characteristic polycrystalline ring patterns for a cubic structure of the clove-generated AgNPs. The hybrid materials showed efficient physical stability,i.e. ξ value of -28.0 mV (for biohybrids without Chla, BH) and of -31.7 mV (for biohybrids labelled with Chla, Chla-BH), assured by strong electrostatic repulsive forces between particles. The "green" nano-silver particles (CE-nAg) showed remarkable antioxidant activity (AA = 90.2%). The biohybrids loaded with clove-AgNPs proved to be more effective, scavenging about 98.8% of free radicals (in case of Chla-BH), and of 92.6% (in case of BH). The antibacterial effectiveness showed that green AgNPs combine in a synergistic manner the antibacterial properties of clove extract with those of silver, resulting in an enhancement of inhibition diameter, by 20%. Chla-BH proved to be more potent against Escherichia coli, than BH, exhibiting an inhibition diameter of 42 mm. Regarding the in vitro cytotoxicity against tumour cells, the CE-nAg concentration significantly influenced the cell viability, i.e. IC50 was 3.6% (v/v) for HT-29 cells. Chla-BH was more effective against HT-29 cancer cells at the concentrations ranging from 0 to 18% (v/v), when the normal cells were not affected. Clove-generated AgNPs exhibited haemolytic activity against hRBCs, while the biohybrids were haemocompatible. The action mechanism on the two cell lines (mouse fibroblast L929 cells and human colorectal adenocarcinoma HT-29 cells) investigated by fluorescence microscopy demonstrated that CE-nAg killed almost all the cells (94%) through necrosis at a concentration of 33.4% (v/v). The treatment of HT-29 cells with BH resulted in: 71.5% viable cells, 19.5% apoptotic and only 9% necrotic cells, while in the case of Chla-BH treatment, only 77.5% cells were viable, 16% cells were apoptotic and 6.5% were necrotic. In this way, the developed silver-based nanoparticles can represent viable promoters to develop new biohybrids with improved features, e.g. antioxidant and antibacterial effectiveness, haemolytic activity and greater specificity towards tumour cells.


Assuntos
Materiais Biomiméticos/química , Química Verde/métodos , Membranas Artificiais , Nanopartículas Metálicas/química , Prata/química , Syzygium/química , Animais , Antibacterianos/farmacologia , Antioxidantes/farmacologia , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Forma Celular/efeitos dos fármacos , Escherichia coli/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Humanos , Lipossomos , Nanopartículas Metálicas/ultraestrutura , Camundongos , Testes de Sensibilidade Microbiana , Espectroscopia de Infravermelho com Transformada de Fourier
16.
Mater Sci Eng C Mater Biol Appl ; 39: 177-85, 2014 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-24863214

RESUMO

Noncovalent entities (consisting of liposomes, phyto-nanosilver and carbon nanotubes) with interesting properties were constructed by a "green" bottom-up method. Phytosynthesis of silver nanoparticles using the Mentha piperita extract combines the benefits of this herb with the interesting properties of silver. The obtained silver-based biohybrids showed antioxidant and antimicrobial properties that have been considerable improved in the presence of carbon nanotubes. Thus the eco-designed bioconstructs consisting of cholesterol-containing liposomes, phytonanosilver and carbon nanotubes exhibited high antioxidant activity (AA=90.8%) and have been shown to be strong biocides offering inhibition zone of 25mm against Escherichia coli and 23mm against Staphylococcus aureus and Enterococcus faecalis.


Assuntos
Anti-Infecciosos/química , Antioxidantes/química , Lipossomos/química , Mentha/química , Nanopartículas Metálicas/química , Nanotubos de Carbono/química , Escherichia coli/efeitos dos fármacos , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Prata/química , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus/efeitos dos fármacos
17.
Beilstein J Nanotechnol ; 5: 2316-25, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25551059

RESUMO

In the last decade, building biohybrid materials has gained considerable interest in the field of nanotechnology. This paper describes an original design for bionanoarchitectures with interesting properties and potential bioapplications. Multilamellar lipid vesicles (obtained by hydration of a dipalmitoyl phosphatidylcholine thin film) with and without cholesterol were labelled with a natural photopigment (chlorophyll a), which functioned as a sensor to detect modifications in the artificial lipid bilayers. These biomimetic membranes were used to build non-covalent structures with single-walled carbon nanotubes. Different biophysical methods were employed to characterize these biohybrids such as: UV-vis absorption and emission spectroscopy, zeta potential measurements, AFM and chemiluminescence techniques. The designed, carbon-based biohybrids exhibited good physical stability, good antioxidant and antimicrobial properties, and could be used as biocoating materials. As compared to the cholesterol-free samples, the cholesterol-containing hybrid structures demonstrated better stability (i.e., their zeta potential reached the value of -36.4 mV), more pronounced oxygen radical scavenging ability (affording an antioxidant activity of 73.25%) and enhanced biocidal ability, offering inhibition zones of 12.4, 11.3 and 10.2 mm in diameter, against Escherichia coli, Staphylococcus aureus and Enterococcus faecalis, respectively.

18.
J Mater Chem B ; 2(21): 3221-3231, 2014 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32261584

RESUMO

Cornelian silver-based architectures were achieved from liposomes, silver nanoparticles (AgNPs) and single-walled carbon nanotubes (SWCNTs) by a "green" bottom-up strategy. Liposomes were prepared by a thin film hydration method and labelled with a natural porphyrin extracted from spinach leaves, cholorophyll a (Chla). Due to its strong visible absorption and fluorescence emission, this phytopigment was used as a spectral sensor to monitor any possible changes occurring in lipid membranes caused by the action of various agents. An aqueous extract from Cornus mas L. fruits was used for AgNP phytosynthesis. Addition of appropriate amounts of phytonanosilver particles and SWCNTs to biomimetic membranes resulted in biohybrid material with good physical stability (ZP = -34 mV) and high antioxidant activity (AA = 97.8%). Moreover, they have been shown to be a strong biocide having diameters of inhibition zones of 18.3 mm, 23.8 mm and 21.6 mm against Escherichia coli ATCC 8738, Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212, respectively. Chla rapidly sensed the modifications that occurred in artificial lipid bilayers as a result of interactions with silver nanoparticles and carbon nanotube surfaces indicating the biohybrid formation, and these results were supported by AFM analysis. The bioconstructed hybrid material consisting of biomimetic membranes, phyto-nanosilver and SWCNTs could be applied as an antimicrobial and antioxidant coating.

19.
J Nanosci Nanotechnol ; 13(3): 2051-60, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23755645

RESUMO

This paper is aimed to describe a simple and rapid eco-friendly bottom-up approach for the preparation of antioxidant silver bionanostructures using a leaf extract from sage (Salvia officinalis L.). The bioreduction property of sage in the synthesis of silver nanoparticles was investigated by UV-VIS and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy. During their preparation, the particle size analysis was performed by using Dynamic Light Scattering technique. Ultrasonic irradiation was used to obtain sage silver nanoparticles. The morphology (size and shape) of the herbal silver nanoparticles was evaluated by Scanning Electron Microscopy that revealed the formation of spherical phytonanoparticles with size less than 80 nm. In order to increase their stability and their biocompatibility, the sage silver nanoparticles were introduced in two types of liposomes: soybean lecithin- and Chla-DPPC-lipid vesicles which were prepared by thin film hydration method. X-Ray Fluorescence analysis confirmed the silver presence in liposomes/sage-AgNPs biohybrids. The stability of liposomes/herbal AgNPs bioconstructs was checked by zeta potential measurements. The most stable biohybrids: Chla-DPPC/sage-AgNPs with zeta potential value of -34.2 mV, were characterized by Atomic Force Microscopy revealing the spherical and quasi-spherical shaped profiles of these nanobiohybrids with size less than 96 nm. The antioxidant activity of the silver bionanostructures was evaluated using chemiluminescence assay. The developed eco-friendly silver phytonanostructures based on lipid membranes, nanosilver and sage extract, manifest strong antioxidant properties (between 86.5% and 98.6%).


Assuntos
Antioxidantes/farmacologia , Lipossomos , Nanopartículas Metálicas , Salvia/química , Prata/química , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Folhas de Planta/química , Espectrometria por Raios X , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier
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