Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Development of a targeted drug delivery system: Monoclonal antibodies adsorption onto bonelike hydroxyapatite nanocrystal surface

Together with cancer biomarker advance, nanotechnology could lead to a "personalized oncology", where early tumour detection and diagnosis are more and more specific. A nanosized drug delivery system is mainly composed of three fundamental elements: i) a drug nanocarrier (1-100 nm), ii) an anti-cancer drug; iii) an active targeting molecule, recognizing a tumour associated marker expressed at the cell surface. In our study we used: i) hydroxyapatite nanocrystals (HA-NC), for its properties of large specific surface area, hydrophilicity and biodegradability with very low toxicity and ii) monoclonal antibodies (mAb), directed against CAR-3, a mucin tumour associated surface antigen, and against the Met/HGF-R, both of which are overexpressed on human carcinomas. In our study, nanosized HA-NC, poorly aggregating and biomimetic, were synthetised and characterized. After a preliminary isothermal adsorption of human polyclonal IgG, we functionalized HA-NC, coated or not with protein A (Prot A), with the two mAbs. IgG and Prot A isothermal adsorption curves were obtained; mAb absorption was achieved and prelimary Prot A coating appeared not to improve HA-NC loading capacity. IgG conformation onto HA-NC was investigated by means of Fourier Transformed InfraRed Spectroscopy, revealing a preferential binding with the constant antibody domain, and exposition of the variable domain, involved in antigen binding, on the biomaterial surface. These immunocomplexes are confirmed to be potentially used as targeted drug delivery system

Does chlorhexidine mouthwash, with an anti-discoloration system, reduce tooth surface discoloration without losing its efficacy? A systematic review and meta-analysis

Objectives: To investigate whether chlorhexidine mouthwash (CHX-MW), with an anti-discoloration system(ADS), is effective in preventing extrinsic tooth surface discoloration. Additionally, this paper seeks to evaluate whether CHX combined with an ADS maintains its efficacy with respect to reducing plaque and gingivitis scores. Material and methods: MEDLINE-PubMed and Cochrane-Central were searched up to October 2018 to identify eligible studies. Papers evaluating the effect of CHX-MW+ADS compared to CHX without an ADS were included. A descriptive analysis and when feasible a meta-analysis was performed. Results: Screening resulted in 13 eligible publications, presenting 16 comparisons. Six of these evaluated the MW in a non-brushing model and ten as an adjunct to toothbrushing. A descriptive analysis demonstrated that the majority showed no differences in bleeding, gingivitis and plaque scores. This was confirmed by the meta-analysis. In non-brushing experiments, the difference-of-means (DiffM) for plaque scores was 0.10 (P = 0.45, 95%CI: [−0.15; 0.34]) and for the gingival index 0.04 (P = 0.15,95%CI: [−0.02; 0.11]). The DiffM in brushing studies for plaque scores was 0.01 (P = 0.29, 95%CI: [−0.01; 0.02]) and for the gingival index 0.00 (P = 0.87,95%CI: [−0.05; 0.06]). With respect to staining scores, the meta-analysis revealed that in non-brushing studies, the standardized mean difference was 3.19 (P = 0.0005,95%CI: [−3.98; −1.41]) while in brushing studies, the DiffM was 0.12 (P = 0.95,95%CI: [−3.32; 3.55]). Conclusion: There is moderate quality evidence from non-brushing studies that the addition of an ADS to CHX-MW reduces tooth surface discoloration and does not appear to affect its properties with respect to gingival inflammation and plaque scores. In brushing studies, there is also moderate quality evidence that ADS does not affect the anti-plaque and anti-gingivitis efficacy of CHX. The majority of comparisons and the meta-analysis including these indicate no significant effect of ADS on tooth staining in situations where the mouthwash is used in addition to toothbrushing