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)

Incomplete surgical excision of keratinocyte skin cancers: a systematic review and meta-analysis.

Background Keratinocyte or non‐melanoma skin cancer (NMSC) is the commonest malignancy worldwide. Usual treatment is surgical excision. Current guidelines underestimate incomplete excision rates. Objectives We aimed to determine the risk of incomplete excision of NMSCs through a systematic review and meta‐analysis of primary clinical studies. Methods A PRISMA‐compliant systematic review and meta‐analysis was performed using methodology proposed by Cochrane. A comprehensive search strategy was applied to MEDLINE, Embase, Scopus, CINAHL, EMCare, Cochrane Library and the grey literature (January 2000–27th November 2019). All studies were included except studies on Mohs micrographic surgery, frozen section or biopsies. Abstract screening and data extraction were performed in duplicate. The risk of bias was assessed using a tool for prevalence/incidence studies. The primary outcome was the proportion of incomplete surgical excisions. A random effects model for pooling of binominal data was used. Differences between proportions were assessed by sub‐group meta‐analysis and meta regression which were presented as risk ratios. PROSPERO CRD42019157936. Results Searching identified 3477 records, with 110 studies included, comprising 53 796 patients with 106 832 basal cell carcinomas (BCC) and 21 569 squamous cell carcinomas (SCC). The proportion of incomplete excisions for BCC was 11·0% (95% CI 9·7‐12·4%) and for SCC 9·4% (95% CI 7·6‐11·4%). Incomplete excisions by specialty were: dermatology 6·2% BCCs, 4·7% SCCs; plastic surgery 9·4% BCCs, 8·2% SCCs; general practitioners 20·4% BCCs, 19·9% SCCs. The risk of incomplete excision for general practitioners was four times that of dermatologists for both BCC (RR 3·9 [95% CI 2·0‐7·3]) and SCC (RR 4·8 [95% CI 1·0‐22·8]). Studies were heterogenous (I2=98%) and at high risk of bias. Conclusions The proportion of incomplete excisions is higher than previously reported. Excisions performed by specialists may lower the risk of incomplete excision