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Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-09-21T19:51:20Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tarciane_silva_pinto.pdf: 4051834 bytes, checksum: d6525c9152e47311a8695bf3eed5c6e6 (MD5) Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-10-09T13:37:54Z (GMT) No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tarciane_silva_pinto.pdf: 4051834 bytes, checksum: d6525c9152e47311a8695bf3eed5c6e6 (MD5) Made available in DSpace on 2017-10-09T13:37:54Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) tarciane_silva_pinto.pdf: 4051834 bytes, checksum: d6525c9152e47311a8695bf3eed5c6e6 (MD5) Previous issue date: 2017 Neste trabalho, Carbon Dots (CDs) obtidos a partir de celulose de algod?o e contendo 4,5 mmol.g-1 de grupos funcionais ?cidos, dos quais 63 % exibiam pKas t?picos de ?cidos carbox?licos foram usados na prepara??o de filmes automontados com os biopol?meros quitosana (QT) e col?geno (CL) a fim de verificar a morfologia, espessura e intera??es moleculares entre os componentes. A quitosana usada apresentou um total de 4,2 mmolg-1 de grupos funcionais -NH2, correspondente a um grau de desacetila??o de ~70 %. Por outro lado, o col?geno hidrolisado apresentou diferentes grupos funcionais com acidez de Br?nsted, t?picos da presen?a de diferentes amino?cidos na estrutura. Todos os filmes finos foram preparados com a t?cnica de deposi??o camada por camada (do ingl?s: Layer-by-layer (LbL)) por meio de imers?o do substrato nas diferentes solu??es. Os materiais foram caracterizados por diferentes t?cnicas, incluindo Microscopia de For?a At?mica, Espectroscopia na regi?o do UV-Vis, Espectroscopia de Resson?ncia de Plasma de Superf?cie e Titula??o Calorim?trica. Em todas as condi??es experimentais utilizadas para o crescimento dos filmes, observou-se um crescimento linear da quantidade de material depositado com o n?mero de imers?es realizadas. No entanto, diferentes condi??es das solu??es dos biopol?meros e da suspens?o de Carbon Dots produziram filmes com espessura e morfologia diferentes. Nos filmes de QT/CDs a quantidade de nanopart?culas depositadas por bicamada, com solu??o de quitosana em pH = 3,5, pH = 5 e pH = 3,5 na presen?a de 0,1 mol/L de NaCl, foram, respectivamente, 11 mg.m-2, 16 mg.m-2 e 24 mg.m-2 sendo as espessuras dos filmes, com 20 bicamadas, correspondentes a estas quantidades foram de 60, 150 e 200 nm. Este resultado ? atribu?do ao aumento da flexibilidade das cadeias polim?ricas dos biopol?meros, as quais est?o menos carregadas. Dessa forma, as cadeias podem apresentar conforma??es mais adequadas para recobrir eficientemente a estrutura das nanopart?culas quase esf?ricas. Al?m disso, o aumento da for?a i?nica da solu??o de Carbon Dots tamb?m contribui para o aumento de material depositado devido ? forma??o de aglomerados sob estas condi??es. Nos filmes de CL/CDs, a quantidade de nanopart?culas depositadas, com solu??o de col?geno em pH = 3,16, pH = 5 e pH = 3,16 na presen?a de 0,1 mol/L de NaCl, foram 2,3 mg.m-2, 6,46 mg.m-2 e 6,41 mg.m-2, respectivamente. No entanto, a energia de intera??o, obtida por calorimetria isot?rmica, ? maior em pH baixo. Em geral, a quantidade de material depositado nos filmes de col?geno ? bem inferior ?s observadas para os filmes de QT/CDs e, consequentemente, filmes com espessuras entre 40 e 50 nm. Al?m disso, n?o foi observada varia??o significativa entre as massas depositadas nestes filmes com o aumento do pH e for?a i?nica. Estes resultados podem estar relacionados ? menor ?carga parcial positiva? sobre as cadeias da prote?na em rela??o a quitosana, observada pelos potenciais zeta nestas condi??es. Por fim, os resultados aqui apresentados sugerem que as estruturas dos filmes, isto ?, morfologia e espessura, podem ser facilmente controladas e reproduzidas manipulando-se as condi??es das solu??es dos biopol?meros, al?m do tradicional n?mero de imers?es. Em adi??o, o estudo pode contribuir para o desenvolvimento de uma nova classe de dispositivos de alto desempenho, como sensores e superf?cies fotoativas. Disserta??o (Mestrado) ? Programa de P?s-Gradua??o em Qu?mica, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. In the present work, Carbon Dots (CDs), obtained from cotton cellulose and containing 4.5 mmol g-1 of acid functional groups, of which 63% exhibited typical pKa?s compared to carboxylic acids, were used in the preparation of self-assembled films with the biopolymers Chitosan (QT) and Collagen (CL) in order to verify the morphology, thickness and molecular interactions among the components. The chitosan used in this work had a total of 4.2 mmol g-1 of functional groups ?NH2, corresponding to a deacetylation degree of ~70%. On the other hand, the hydrolyzed collagen showed different functional groups with Br?nsted acidity typical to the presence of different amino acids in the structure. All the thin films were prepared using the Layer-by-layer method (LbL) by immersing the substrate in different solutions. The materials were characterized by several techniques, such as Atomic Force Microscopy, UV-Vis Spectroscopy, Surface Plasmon Resonance and Calorimetric Titration. It was observed, in all experimental conditions for the growth of the films, a linear increase in the amount of deposited material with the number of immersions performed. However, different conditions of the biopolymer solutions produced films with different thickness and morphology. In the films QT/CDs the amount of nanoparticles deposited per bilayer, with the chitosan solution at pH = 3.5, pH = 5 and pH = 3.5 with the presence of 0.1 mol L-1 of NaCl, were, respectively, 11 mg m-2, 16 mg m-2 and 24 mg m-2 with the thickness of the film, at 20 bilayers, at 60, 150 and 200 nm. This result is associated to the increase in the flexibility of the polymeric chains of the biopolymers, which are less charged. Thus, the chains can present conformations that are proper to cover more efficiently the structure of the almost spherical nanoparticles. Furthermore, the increase of the ionic strength of the Carbon Dots solution also contributes to the increase of the material deposited due to the formation of agglomerates in these conditions. In the films CL/CDs, the amount of nanoparticles deposited, with the collagen solution at pH = 3.16, pH = 5 and pH3.16 in the presence of 0.1 mol L-1 of NaCl, were 2.3 mg m-2, 6.46 mg m-2 and 6.41 mg m-2, respectively. However, the interaction energy, obtained by isothermal calorimetry, is higher in low pH. In general, the amount of material deposited on the collagen films is much lower than that observed for the QT/CDs films and, consequently, films thickness are 40 and 50 nm. Besides that, it was not observed any significant variation between the masses deposited in these films with the increase of the pH and the ionic strength. These results may be associated to the lower ?partial positive charge? on the protein chains in relation to the chitosan, observed by the zeta potentials in these conditions. The presented results suggest that the structures of the films, i.e. morphology and thickness, can be easily controlled and reproduced manipulating the conditions of the biopolymer solutions and the number of immersions. Additionally, the study may contribute to the development of a new class of high performance devices, such as sensors and photoactive surfaces.