Echipa CDI Materiale multifuncționale și compuși biologic activi are expertiză în domeniul materialelor avansate și desfășoară activități de cercetare ce vizează obținerea, caracterizarea și testarea aplicațiilor nanostructurilor hibride funcționalizate, materialelor polimerice și a compușilor bioactivi cu proprietăți controlate.
Tematici de cercetare:
- Nanostructuri hibride funcționalizate pe baza de nanoparticule magnetice și compuși organici
- Micro/nanogeluri magnetice inteligente pentru aplicaţii în biotehnologii şi nanomedicină
- Nanoparticule magnetice și clusteri magnetici cu proprietăți controlate pentru aplicații în separare magnetică, depoluare, nanomedicină și securitate
- Noi polimeri/ copolimeri cu proprietăți speciale pentru aplicații în industria farmaceutică și medicină
- Caracterizarea complexă a materialelor multifuncționale: corelația nanostructură-proprietăți, proprietăți responsive la stimuli externi, interacții specifice cu biomolecule și anumite medicamente, reciclabilitate (spectroscopie de fotoelectroni cu excitare raze X (XPS), spectroscopie FTIR, spectroscopie Raman; spectroscopie EELS); determinarea poziţiei în scală absolută (faţă de vacuum) a benzilor de valenţă şi conducţie cu ajutorul metodelor XPS, UPS şi UV-vis la nanoparticule semiconductoare
- Sinteză de nanomateriale cu proprietăți controlate, utilizând reactivi prietenoși față de mediu
- Nanoparticule magnetice și structuri de carbon modificate cu oxizi metalici – sinteză și caracterizare. Aplicații în depoluare și medicină
- Extracția și caracterizarea compușilor bioactivi din plante
- Îmbunătățirea calității produselor cosmetice utilizând extracte naturale din plante cu proprietăți antioxidante și fotoprotectoare
- Utilizarea extractelor din plante pentru îmbunătățirea calității produselor alimentare
- Aplicații ale nanomaterialelor și ale compușilor bioactivi pentru depoluare
- Aplicații ale metodelor cromatografice (HPLC, TLC) și spectrofotometrice (UV-Vis) în analiza poluanților din mediul înconjurător și determinarea calității medicamentelor, calității produselor alimentare, purității compușilor organici și organo-metalici sintetizați
- Determinarea influenţei factorilor de stres asupra dezvoltării plantelor şi compuşilor bioactivi din plante
4-Hydroxymandelic acid a typical α-hydroxy acid was polymerized by thermal treatment. Surprisingly, instead of the commonly observed polyester formation (e. g. in case of lactic or glycolic acid), C-C-bond connection between the phenolic units of 4-hydroxymandelic acid, by Friedel-Crafts alkylation, occurred resulting in polymers containing carboxylic and phenolic moieties. In addition, lactone formation by reaction between phenol and carboxyl groups in appropriate positions took place leading to benzofuranone units in the final polymer. Thus, poly(benzofurane-co-arylacetic acid) structures, a novel type of organic polymer, were obtained. Interestingly, branching of the polymer chain was also detected. Detailed analysis of these polymerized 4-hydroxymandelic acids (PHMA) by spectroscopic methods revealed formation of oligomers up to 15-mers. Moreover, the three reactive units (acid, phenol, lactone) in the structureof PHMA provide orthogonal reactivity: i) lactone rings reacted with 7-amino-4-methylquinolin-2(1H)-one by amide bond formation. ii) phenol groups were O and/or C-propargylated by reaction with propargyl bromide. iii) Propargylated as well as unmodified PHMA were used as coating for magnetite nanoparticles by Steglich esterification exploiting the carboxyl reactivity of the PHMA. Propargylated products were submitted to CuAAC click reaction in order to link functions of potential practical interest in nanomedicine and organocatalysis. The extreme easiness of preparation and the widespread reactivity render PHMA attractive for many applications.
Magnetic nanoparticles coated with functional polymers play an important role in clean ways of catalysis and water treatment as well as in nanomedicine. Known systems either contain only terminal functions or polymers with pendant positively charged groups. Poly(tartaric acid) (PTA) as a new polymer with multiple pendant negatively charged carboxylate groups was pursued useful for coating magnetic nanoparticles. Simple heating of tartaric acid as a sustainable natural product without using a solvent or a catalyst under controlled conditions leads to poly(tartaric acid). The reaction runs in the solid state by elimination of water and traces of carbon oxides. The structure of the resulting poly(tartaric acid) consists mainly of polyester moieties with pendant carboxyl groups and some lactide units. It was elucidated by mass spectrometry, solid-state 13C nuclear magnetic resonance (13C ss-NMR) and Fourier-transform infrared spectroscopy (FTIR). The properties of the products depend in part on the type of starting materials (L-tartaric acid or D,L-tartaric acid). Pendant carboxyl and hydroxyl groups provide hydrophilicity and the possibility to link functions of interest. The PTA was used as new functional coatings for magnetite nanoparticles in a clean way by mixing the components and magnetic separation. The chemical stability of the magnetic nanoparticles covered by PTA was studied by UV-VIS spectroscopy in water for three weeks. Further linkage of amino-containing entities of practical interest was demonstrated by covalently binding of glucosamine.
For specific applications in the field of high gradient magnetic separation of biomaterials, magnetic nanoparticle clusters of controlled size and high magnetic moment in an external magnetic field are of particular interest. High magnetization magnetic microgels with superparamagnetic behaviour have been obtained in a two-step synthesis procedure by miniemulsion technique using highly stable ferrofluid on volatile nonpolar carrier. Spherical clusters of closely packed hydrophobic oleic acid coated magnetite nanoparticles were coated with cross linked polymer shells of polyacrylic acid, poly-N-isopropylacrylamide, poly-3 -acrylamidopropyl trimethylammonium chloride. The experiments using High Gradient Magnetic Separator show high values of the separation efficiency (99.9 – 99.97%) for the magnetic microgels.
The flow behavior of practically structureless ferrofluids was tuned over a large range by adding well-defined amounts of magnetite nanoparticle clusters. Magnetite nanoparticle clusters with hydrophobic coating were dispersed in high colloidal stability transformer oil based ferrofluid samples, initially free of clusters. The resulting ferrofluid composition consists both of single (approx. 7 nm mean size) and clustered (280 nm average size) magnetite nanoparticles. The magnetite nanoparticle clusters obtained by a solvothermal method have a saturation magnetization of 75 emu g−1 and a remnant magnetization of 0.2 emu g−1 due to the large size (∼25 nm) of the magnetite nanoparticles in their composition. The bidisperse magnetic nanocomposite suspensions investigated provide a promising new formulation of magnetorheological fluids with improved kinetic stability to be used in seismic dampers and flow control devices.
The efficiency of several types of multi-walled carbon nanotubes (MWCNTs) were tested for the retention of the selected antibiotics (ampicillin, ceftazidime, cefepime, imipenem, piperacillin, tazobactam, tetracycline, erythromycin, ciprofloxacin, norfloxacin, vancomycin, gentamicin) from wastewater samples. The retention percentages of the selected antibiotics from waters ranged between ∼40 and 97%. The best percentages of retention were obtained for norfloxacin 97.03% and ciprofloxacin 97.10%. The suspensions of the MWCNTs improved the removal of the antibiotic from wastewaters.
The optimized lipophilic extract of sea buckthorn was added as colorant into the cream cheese. Following the addition of the extract, it was found that the cream cheese was positively influenced by sea buckthorn lipophilic extracts increasing the antiradical activity and inhibiting the growth of the germ in the cream cheese. Moreover, the addition of sea buckthorn extracts did not adversely affect the sensory characteristics of the product. This research demonstrates the possibility of using sea buckthorn lipophilic extract in the production of functional foods. A particular interest is the possibility of replacing synthetic antioxidants with natural ones obtained from local horticultural sources in order to provide consumers with safe and stable food products.
