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Papers by Tache Andreia

Chemical Papers, doi:10.2478/s11696-014-0559-1, Mar 1, 2014

Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with w... more Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with wine and subjected to thermal alteration at constant elevated temperature ((60 ± 2)◦C) in darkness for 12 weeks. This work sought to characterise the samples thereby obtained from chemical and mineralogical perspectives using scanning electron microscopy and an energy-dispersive X-ray microanalysis system (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and capillary electrophoresis (CE) with UV detection as an alternative to chromatographic methods, due to its good resolution, automation, simplicity, high speed, low consumption of chemicals and short time required for sample preparation. The capillary electrophoresis method was used for the detection of five wine biomarkers: succinic acid, malic acid, tartaric acid, citric acid and lactic acid. In general, it was noted that the fine-grained ceramic assortment retained the organic material better than the coarser-grained ceramics...

Chemical Papers, doi:10.2478/s11696-014-0559-1, Mar 1, 2014

Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with w... more Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with wine and subjected to thermal alteration at constant elevated temperature ((60 ± 2)◦C) in darkness for 12 weeks. This work sought to characterise the samples thereby obtained from chemical and mineralogical perspectives using scanning electron microscopy and an energy-dispersive X-ray microanalysis system (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and capillary electrophoresis (CE) with UV detection as an alternative to chromatographic methods, due to its good resolution, automation, simplicity, high speed, low consumption of chemicals and short time required for sample preparation. The capillary electrophoresis method was used for the detection of five wine biomarkers: succinic acid, malic acid, tartaric acid, citric acid and lactic acid. In general, it was noted that the fine-grained ceramic assortment retained the organic material better than the coarser-grained ceramics...

A novel aptamer and surface plasmon resonance (SPR)-based sensor was developed for the label-free... more A novel aptamer and surface plasmon resonance (SPR)-based sensor was developed for the label-free detection of lysozyme. The aptasensor is characterised by a detection limit of 1 μg mL−1 and a linear range of 5–50 μg mL−1. As an application, we examined the usefulness of the aptasensor for monitoring the early stages of the aggregation of lysozyme. It was surprisingly found that, despite a significant decrease in monomer content during aggregation, the response of the aptasensor for protein solutions aged for 12 hours was similar to that for the fresh protein. To correlate the results obtained with the aptasensor with the composition of lysozyme solutions at various time points, we examined them in detail by atomic force microscopy (AFM), thioflavin T fluorescence, size-exclusion chromatography (SEC) and Matrix Assisted Laser Desorption Ionisation Time of Flight Mass Spectrometry (MALDI-TOF-MS). All methods together indicated that during the initial hours of aggregation, the protein solutions contained small lysozyme oligomers (mainly dimers) and decreasing amounts of monomers. Our results thus suggest that the aptamer also recognizes lysozyme dimers/oligomers. A higher non-specific binding was observed for the aggregated lysozyme at the surface of the aptasensor as compared to the native protein. This was attributed to the hydrophobic patches which are exposed by the unfolded lysozyme and/or oligomer species, allowing for different adsorption and organisation at the surface of the aptasensor. This hypothesis is supported by square wave voltammetry (SWV) studies using solutions of aggregated lysozyme. A higher electrochemical signal due to the direct oxidation of tyrosine/tryptophan residues was observed for aged protein solutions as compared to the fresh solution, indicative of an increased number of such exposed electroactive residues and of overall increased surface hydrophobicity of the protein. Our work presents a label-free lysozyme aptasensor that is useful not only for the detection of the protein monomer but also for observing the onset of aggregation. The approach can be extended to other proteins which are prone to aggregation.

This study aimed to assess the antioxidant compound effects on oxidisable substrates, using an ef... more This study aimed to assess the antioxidant compound effects on oxidisable substrates, using an effective bio-mimetic system based on human low density lipoproteins (LDL). Thermally generated radicals induce LDL oxidative changes to be identified and quantified. The bio-mimetic system thus developed responded linearly to radicals’ concentration over a range of 10−6-10−5 mol L−1. Cu2+ accentuates lipoperoxidation but, when rosmarinic acid was present, Cu2+ produced an unexpected effect, i.e. increased antioxidant efficiency against lipoperoxidation. Rosmarinic acid inhibits production of lipoperoxides by up to 30 % in the absence of Cu2+ and up to 70 % in its presence when the rosmarinic acid-to-Cu molar ratio is 1: 1.

The aim of this study was to prove the efficiency of the nanofiltration process for the concentra... more The aim of this study was to prove the efficiency of the nanofiltration process for the concentration of polyphenolic compounds from Geranium robertianum and Salvia officinalis extracts and to evaluate the extract's antioxidant activity. A lab-scale cross-flow set-up using flat-sheet configuration membrane was employed for all experiments. Two nanofiltration membranes have been used: SelRO MPF-36 (Koch membrane) and an organic-inorganic membrane (polysulfone with SBA-15-NH 2 ). When the organic-inorganic membranes were used in the nanofiltration process, the obtained concentrated extracts proved to have higher polyphenol and flavonoid rejections, in both cases (Geranium robertianum and Salvia officinalis). The obtained values were over 88 % DPPH inhibition, for concentrated extracts, using the DPPH method. The concentrated extracts obtained after nanofiltration NF2 (organic-inorganic membrane) had the strongest scavenging activity for all extracts and almost completely inhibited DPPH absorption (92.9 % for Geranium robertianum concentrated extract and 90.1 % for Salvia officinalis concentrated extract). These features turn the studied, concentrated extracts into a good source for further medicinal applications.

Matrix assisted laser desorption-ionization time of flight (MALDI-ToF) and infrared techniques we... more Matrix assisted laser desorption-ionization time of flight (MALDI-ToF) and infrared techniques were used to study oxidative modification of low density lipoproteins (LDL), considered to have the key role in biological process that initiates and accelerates the development of cardiovascular disease. The early identification of lipoperoxidation products creates the opportunity of the efficient prevention of eventual oxidative damages. MALDI analysis of LDL subjected to in vitro oxidation process initiated by 2,2-azobis(2-amidinopropane) dihydrochloride revealed that some fragments of lipoprotein changed the molecular weight by 16 and 32 Da due to the oxygen or hydroxyl groups attachment, and peroxide or hydroperoxide formation, while Fourier Transformed Infrared studies proved that lipoprotein changes its protein secondary conformation from predominantly α-helix in predominantly β-turn. The increase in free radicals concentration correlated to structural changes, and the presence of transitional metal ion, copper (II), in the oxidation process lead to an enhancing of the damaging effects of free radicals on lipoprotein substrate. It was shown that the toxic effects of oxidants are delayed by the presence of glutathione (10 mM), an endogenous antioxidant.

Low density lipoprotein self-assembled layers on gold support, proposed as model for oxidation st... more Low density lipoprotein self-assembled layers on gold support, proposed as model for oxidation studies, were subjected to oxidation processes using different oxidative agents: 2,2′-Azobis(2methylpropionamidine)dihydrochloride, atmospheric oxygen, and metal-induced oxidation. The freshly prepared and the oxidized layers were characterized by X ray photoelectron spectroscopy (XPS), Fourier-Transformed infrared spectroscopy, and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-ToF) mass spectrometry to discriminate the effects of oxidative reagents. Data obtained from FTIR and MALDI spectra proved the lipoperoxide formation subsequent to reactive oxygen species attack and the opportunity to use the model to discriminate between oxidation toxicity.

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Acest articol prezintă un nou instrument electroanalitic -electrod de aur modificat cu lipoprotei... more Acest articol prezintă un nou instrument electroanalitic -electrod de aur modificat cu lipoproteină umană de densitate mică -capabil să funcţionze ca un sistem biomimetic al răspunsului pereţilor celulari la stresul oxidativ indus prin atacul unor radicali liberi. Sunt prezentate rezultatele obţinute la aplicarea acestui instrument în evaluarea eficacităţii antioxidante a unor polifenoli în prevenirea lipoperoxidării. Aceşti polifenoliau fost ordonaţi în funcţie de eficienţa lor în prevenirea lipoperoxidării: acid cafeic >acid rosmarinic>acid clorogenic. This paper presents a new developed electro-analytical tool -gold modified electrode with low-density lipoprotein -able to mimic the biological response of cellular wall against the oxidative damage induced by free radicals attack. Results obtained when applying this tool in the assessment of the polyphenols antioxidative efficacy against lipoperoxidation are reported. These polyphenols have been ordered in function of their efficiency in preventing lipoprotein oxidation: Caffeic acid > Rosmarinic acid > Chlorogenic acid.

scientificbulletin.upb.ro

În lucrarea de faţă sunt prezentate rezultatele noastre experimentale privind biofuncţionalizarea... more În lucrarea de faţă sunt prezentate rezultatele noastre experimentale privind biofuncţionalizarea nanoparticulelor de siliciu (SiNP), utilizând un polymer biocompatibil-chitosanul. Procedura constă în două etape şi a fost dezvoltată pentru a ataşa eficient bioplimerul chitosan de suprafaţa nanoparticulelor de siliciu. Utilizând triethoxsililbutiraldehida, un compus al siliciului cu grup funcţional carboxil terminal, în locul altor silani cunoscuţi a redus timpul necesar pentru a ataşa acoperirea necesară. Analiza spectrelor FT-IR înregistrate pentru nanoparticulele de siliciu acoperite cu filmul biopolimeric a demonstrat prezenţa la suprafaţa acestora a grupărilor funcţionale -NH2 şi -OH disponibile pentru legarea ulterioară a unor medicamente utilizate în tratamentul cancerului. Filmul polimeric chitosan şi-a menţinut structura în stare nativă, pastrându-şi astfel proprietăţile de biocompatibilitate.

The development of the composite materials based on metallic complex has made a huge progress in ... more The development of the composite materials based on metallic complex has made a huge progress in the last years. These studies led to new synthesis procedures, capable of providing extended, stable wide pores structures, polymeric matrix and transitional metal ions in the polymeric matrix .

Book Chapters by Tache Andreia

www.intechopen.com, Infrared Spectroscopy – Materials Science, Engineering and Technology

Chemical Papers, doi:10.2478/s11696-014-0559-1, Mar 1, 2014

Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with w... more Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with wine and subjected to thermal alteration at constant elevated temperature ((60 ± 2)◦C) in darkness for 12 weeks. This work sought to characterise the samples thereby obtained from chemical and mineralogical perspectives using scanning electron microscopy and an energy-dispersive X-ray microanalysis system (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and capillary electrophoresis (CE) with UV detection as an alternative to chromatographic methods, due to its good resolution, automation, simplicity, high speed, low consumption of chemicals and short time required for sample preparation. The capillary electrophoresis method was used for the detection of five wine biomarkers: succinic acid, malic acid, tartaric acid, citric acid and lactic acid. In general, it was noted that the fine-grained ceramic assortment retained the organic material better than the coarser-grained ceramics...

Chemical Papers, doi:10.2478/s11696-014-0559-1, Mar 1, 2014

Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with w... more Experimentally developed ceramic pots, with two different sizes of grain, were half-filled with wine and subjected to thermal alteration at constant elevated temperature ((60 ± 2)◦C) in darkness for 12 weeks. This work sought to characterise the samples thereby obtained from chemical and mineralogical perspectives using scanning electron microscopy and an energy-dispersive X-ray microanalysis system (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and capillary electrophoresis (CE) with UV detection as an alternative to chromatographic methods, due to its good resolution, automation, simplicity, high speed, low consumption of chemicals and short time required for sample preparation. The capillary electrophoresis method was used for the detection of five wine biomarkers: succinic acid, malic acid, tartaric acid, citric acid and lactic acid. In general, it was noted that the fine-grained ceramic assortment retained the organic material better than the coarser-grained ceramics...

A novel aptamer and surface plasmon resonance (SPR)-based sensor was developed for the label-free... more A novel aptamer and surface plasmon resonance (SPR)-based sensor was developed for the label-free detection of lysozyme. The aptasensor is characterised by a detection limit of 1 μg mL−1 and a linear range of 5–50 μg mL−1. As an application, we examined the usefulness of the aptasensor for monitoring the early stages of the aggregation of lysozyme. It was surprisingly found that, despite a significant decrease in monomer content during aggregation, the response of the aptasensor for protein solutions aged for 12 hours was similar to that for the fresh protein. To correlate the results obtained with the aptasensor with the composition of lysozyme solutions at various time points, we examined them in detail by atomic force microscopy (AFM), thioflavin T fluorescence, size-exclusion chromatography (SEC) and Matrix Assisted Laser Desorption Ionisation Time of Flight Mass Spectrometry (MALDI-TOF-MS). All methods together indicated that during the initial hours of aggregation, the protein solutions contained small lysozyme oligomers (mainly dimers) and decreasing amounts of monomers. Our results thus suggest that the aptamer also recognizes lysozyme dimers/oligomers. A higher non-specific binding was observed for the aggregated lysozyme at the surface of the aptasensor as compared to the native protein. This was attributed to the hydrophobic patches which are exposed by the unfolded lysozyme and/or oligomer species, allowing for different adsorption and organisation at the surface of the aptasensor. This hypothesis is supported by square wave voltammetry (SWV) studies using solutions of aggregated lysozyme. A higher electrochemical signal due to the direct oxidation of tyrosine/tryptophan residues was observed for aged protein solutions as compared to the fresh solution, indicative of an increased number of such exposed electroactive residues and of overall increased surface hydrophobicity of the protein. Our work presents a label-free lysozyme aptasensor that is useful not only for the detection of the protein monomer but also for observing the onset of aggregation. The approach can be extended to other proteins which are prone to aggregation.

This study aimed to assess the antioxidant compound effects on oxidisable substrates, using an ef... more This study aimed to assess the antioxidant compound effects on oxidisable substrates, using an effective bio-mimetic system based on human low density lipoproteins (LDL). Thermally generated radicals induce LDL oxidative changes to be identified and quantified. The bio-mimetic system thus developed responded linearly to radicals’ concentration over a range of 10−6-10−5 mol L−1. Cu2+ accentuates lipoperoxidation but, when rosmarinic acid was present, Cu2+ produced an unexpected effect, i.e. increased antioxidant efficiency against lipoperoxidation. Rosmarinic acid inhibits production of lipoperoxides by up to 30 % in the absence of Cu2+ and up to 70 % in its presence when the rosmarinic acid-to-Cu molar ratio is 1: 1.

The aim of this study was to prove the efficiency of the nanofiltration process for the concentra... more The aim of this study was to prove the efficiency of the nanofiltration process for the concentration of polyphenolic compounds from Geranium robertianum and Salvia officinalis extracts and to evaluate the extract's antioxidant activity. A lab-scale cross-flow set-up using flat-sheet configuration membrane was employed for all experiments. Two nanofiltration membranes have been used: SelRO MPF-36 (Koch membrane) and an organic-inorganic membrane (polysulfone with SBA-15-NH 2 ). When the organic-inorganic membranes were used in the nanofiltration process, the obtained concentrated extracts proved to have higher polyphenol and flavonoid rejections, in both cases (Geranium robertianum and Salvia officinalis). The obtained values were over 88 % DPPH inhibition, for concentrated extracts, using the DPPH method. The concentrated extracts obtained after nanofiltration NF2 (organic-inorganic membrane) had the strongest scavenging activity for all extracts and almost completely inhibited DPPH absorption (92.9 % for Geranium robertianum concentrated extract and 90.1 % for Salvia officinalis concentrated extract). These features turn the studied, concentrated extracts into a good source for further medicinal applications.

Matrix assisted laser desorption-ionization time of flight (MALDI-ToF) and infrared techniques we... more Matrix assisted laser desorption-ionization time of flight (MALDI-ToF) and infrared techniques were used to study oxidative modification of low density lipoproteins (LDL), considered to have the key role in biological process that initiates and accelerates the development of cardiovascular disease. The early identification of lipoperoxidation products creates the opportunity of the efficient prevention of eventual oxidative damages. MALDI analysis of LDL subjected to in vitro oxidation process initiated by 2,2-azobis(2-amidinopropane) dihydrochloride revealed that some fragments of lipoprotein changed the molecular weight by 16 and 32 Da due to the oxygen or hydroxyl groups attachment, and peroxide or hydroperoxide formation, while Fourier Transformed Infrared studies proved that lipoprotein changes its protein secondary conformation from predominantly α-helix in predominantly β-turn. The increase in free radicals concentration correlated to structural changes, and the presence of transitional metal ion, copper (II), in the oxidation process lead to an enhancing of the damaging effects of free radicals on lipoprotein substrate. It was shown that the toxic effects of oxidants are delayed by the presence of glutathione (10 mM), an endogenous antioxidant.

Low density lipoprotein self-assembled layers on gold support, proposed as model for oxidation st... more Low density lipoprotein self-assembled layers on gold support, proposed as model for oxidation studies, were subjected to oxidation processes using different oxidative agents: 2,2′-Azobis(2methylpropionamidine)dihydrochloride, atmospheric oxygen, and metal-induced oxidation. The freshly prepared and the oxidized layers were characterized by X ray photoelectron spectroscopy (XPS), Fourier-Transformed infrared spectroscopy, and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-ToF) mass spectrometry to discriminate the effects of oxidative reagents. Data obtained from FTIR and MALDI spectra proved the lipoperoxide formation subsequent to reactive oxygen species attack and the opportunity to use the model to discriminate between oxidation toxicity.

scientificbulletin.upb.ro

Acest articol prezintă un nou instrument electroanalitic -electrod de aur modificat cu lipoprotei... more Acest articol prezintă un nou instrument electroanalitic -electrod de aur modificat cu lipoproteină umană de densitate mică -capabil să funcţionze ca un sistem biomimetic al răspunsului pereţilor celulari la stresul oxidativ indus prin atacul unor radicali liberi. Sunt prezentate rezultatele obţinute la aplicarea acestui instrument în evaluarea eficacităţii antioxidante a unor polifenoli în prevenirea lipoperoxidării. Aceşti polifenoliau fost ordonaţi în funcţie de eficienţa lor în prevenirea lipoperoxidării: acid cafeic >acid rosmarinic>acid clorogenic. This paper presents a new developed electro-analytical tool -gold modified electrode with low-density lipoprotein -able to mimic the biological response of cellular wall against the oxidative damage induced by free radicals attack. Results obtained when applying this tool in the assessment of the polyphenols antioxidative efficacy against lipoperoxidation are reported. These polyphenols have been ordered in function of their efficiency in preventing lipoprotein oxidation: Caffeic acid > Rosmarinic acid > Chlorogenic acid.

scientificbulletin.upb.ro

În lucrarea de faţă sunt prezentate rezultatele noastre experimentale privind biofuncţionalizarea... more În lucrarea de faţă sunt prezentate rezultatele noastre experimentale privind biofuncţionalizarea nanoparticulelor de siliciu (SiNP), utilizând un polymer biocompatibil-chitosanul. Procedura constă în două etape şi a fost dezvoltată pentru a ataşa eficient bioplimerul chitosan de suprafaţa nanoparticulelor de siliciu. Utilizând triethoxsililbutiraldehida, un compus al siliciului cu grup funcţional carboxil terminal, în locul altor silani cunoscuţi a redus timpul necesar pentru a ataşa acoperirea necesară. Analiza spectrelor FT-IR înregistrate pentru nanoparticulele de siliciu acoperite cu filmul biopolimeric a demonstrat prezenţa la suprafaţa acestora a grupărilor funcţionale -NH2 şi -OH disponibile pentru legarea ulterioară a unor medicamente utilizate în tratamentul cancerului. Filmul polimeric chitosan şi-a menţinut structura în stare nativă, pastrându-şi astfel proprietăţile de biocompatibilitate.

The development of the composite materials based on metallic complex has made a huge progress in ... more The development of the composite materials based on metallic complex has made a huge progress in the last years. These studies led to new synthesis procedures, capable of providing extended, stable wide pores structures, polymeric matrix and transitional metal ions in the polymeric matrix .

www.intechopen.com, Infrared Spectroscopy – Materials Science, Engineering and Technology