Current Organic Chemistry - Volume 22, Issue 12, 2018

Background: Biodegradable antimicrobial materials for food packaging applications are in great demand by the food industry and society alike for the purposes of extending food shelf life, thus reducing the environmental impacts associated with synthetic plastics. Among the natural and non-toxic active compounds available, essential oils and their major components have been widely studied due to their antioxidant and antimicrobial properties together with their Generally Recognized as Safe status. Objective: In this review, the antimicrobial and antioxidant properties of several essential oils and their major compounds are summarized, as well as their action when included in different biopolymer-based matrices. Both the method of incorporating active ingredients into the biopolymer matrix and the yield of such processes as a function of the technique used (casting methods or thermoplastic processing) are also assessed. The effect of active compounds on the functional properties of the films is reviewed, as well as the effective release of the active ingredients into different food systems and food simulants, as affected by polymer-active interactions and the nature of the food. Conclusion: Finally, the antimicrobial action of some of these active compounds (embedded in different biopolymer matrices) is also discussed both in in vitro studies and in antimicrobial tests performed using foods of different compositions.

Background: The search for a drug delivery system is a highly desirable target when toxic drugs are considered (e.g. chemotherapeutics) or when the site of action of a drug is difficult to approach due to the pharmacokinetic profile of the chosen therapeutic agent. Objective: Among the different delivery systems, those based on natural or semi-synthetic polysaccharides are very promising, due to their biocompatibility and biodegradability. Up to now, different polysaccharides are investigated, mainly based on chitosan, alginic acid, dextran and hyaluronic acid. Method: These compounds are easily chemically modified, so that derivatives able to form nanoparticles or micro vector by interaction with other chemicals (e.g. by ionotropic gelation). These delivery systems can be loaded with the drug of interest in a way that dramatically change its pharmacokinetic profile, and further derivatization with molecules that selectively target the site of interest (e.g. neoplastic cells) is possible. Results and Conclusion: In this review, we describe the state-of-the-art of polysaccharide-based biopolymeric drug delivery systems developed into the last ten years, with a particular attention to the most commonly used polysaccharides (dextran, chitosan, hyaluronic acid, alginic acid), the chemical derivatization procedures and the perspective use of the obtained vehicles in clinical medicine.

Background: Regenerative medicine deals with developing strategies to repair or substitute organ or tissue functionality; it involves any combination of specific cell types, engineered polymeric biomaterials with biochemical inducers to promote cell adhesion, migration, growth, and differentiation to restore physiological tissue function, and to stimulate regeneration of damaged and previously irreparable organs. Nanotechnology- based approaches have been investigated towards for the development of innovative multifunctional biodegradable biomaterials for tissue engineering, that can serve as scaffolds for cells, but also allow monitoring the tissue regeneration process, controlling the delivery of therapeutic agents, and/or the occurrence of biological reactions responsible for organogenesis. Physical, chemical, and biological control of cell micro- and nanoenvironment are of key importance for the ability to direct and manipulate the cell behaviour. This has led to the development of new techniques enabling the fabrication of micro- and nanostructured biodegradable constructs suitable for regenerative medicine applications. Objective: This contribution gives an extensive overview of nanostructured polymeric biomaterial preparation, characterization and stem cell interaction. The review starts with an introduction on regenerative medicine, stem cells, and polymeric biomaterials, then the different techniques employed for the development of the scaffolds will be described, analyzing solvent-based, gas-based and additive manufacturing techniques, highlighting their principles, technological solutions and processes. Conclusion: The synthesis of nanostructured biopolymeric nanoparticle bearing specific stabilizing agents can open new challenges in the development of personalized health care products. A deep knowledge has to be acquired on the chemical behaviour of the nanomaterials and on the interactions they establish with the bioenvironments. Finally, recent advances and emerging designs and applications will be discussed.

Increased awareness to eco-friendliness and finite petroleum resources trigger growing interest in maximizing the use of low environmental impact and renewable materials. In the last decades, lignocellulosic based materials at the nanoscale level have attracted the attention of research and industry, due to their renewable nature and their abundant availability, their high reactivity surface and functionality, their low density and cost. The exceptional physical properties, combined with high aspect ratio and large surface area allow their use in a large variety of polymers at low concentration as compared to composite loading. Recently, in this context, nanocomposite approach was largely investigated as a strategy to upgrade the functional and structural properties of synthetic/ traditional and/or natural polymers, in addition, the combination of sustainable and bioresorbable polymers with bio-based nanofiller opened new perspectives in the self-assembly of nanomaterials for different sectors with tunable thermal, mechanical and degradative properties. In this review article, the addition of lignocellulosic reinforcement phases (lignin and cellulosic-based nanofillers) and their combined effect on physical, functional and structural properties of different polymers (including thermoplastic and thermosetting) were reported and discussed. Considering the required functionality, the role of cellulose and lignin-based nanostructures when embedded in different biopolymers was analyzed and summarized here in terms of different effect (microstructural, thermal-degratative, optical, mechanical, chemical, biological, barrier and degradative characteristics).

Background: Natural polysaccharides such as alginates, pectins, and chitins, possess a wide versatility in addition to the variability of the typical structural features of polysaccharides, as they include amino-, amido-, carboxylic acid, and esters groups. Objective: These functional groups can be exploited to graft specific moieties and macromolecules, thus tailoring the specific characteristics when envisioning improved functionality, such as targeted-drug delivery, antimicrobial, and thermo- or pHresponsiveness. Ad hoc covalent modifications of the polysaccharidic backbone can promote the loading and interactions with a wide variety of both hydrophilic and hydrophobic substances, as well as enhanced cell adhesion able to promote regeneration events. Additionally, enzymatic modifications have been conducted to have precise control of both functional groups and biodegradation. Conclusion: This review intends to give an overview over chemical and enzymatic reactions to modify the backbone of polysaccharides aiming to exploit organic chemistry tools applied to meet the diverse needs of biomedicine.

The industrial interest for microencapsulation techniques to produce innovative materials has increased in the last years. Microencapsulation shows several advantages for textile industries since active compounds, such as vitamins, essential oils, antimicrobials and/or antibiotics can be isolated to protect them from environment factors (oxygen, light, moisture and temperature). Microcapsules are also used for the controlled release of fragrances or even heat, to mask undesired properties of the active components and to convert liquid substances into solids with increased compatibility. In this review, the application of microencapsulation techniques to obtain innovative materials for the textile sector has been highlighted. The main known techniques have been briefly described, including interfacial, suspension and in situ polymerizations as well as spray drying, complex coacervation, centrifugal extrusion processes, fluidized-bed-coating and sol-gel techniques. Different mechanisms have been also described based on the different properties offered by permeable or non-permeable capsules. Finally, the development and application of microencapsulation in smart (phase change materials, photochromic, thermochromic and flame retardant microcapsules) and active textiles, including antimicrobials and the use of different additives with pharmaceutical and/or medical properties, insect-repellent systems and fragrant solid carrier materials have been briefly discussed.

Background: β-glucans are naturally occurred polysaccharides of glucose units, present in the cell wall of various living organisms such as bacteria, yeast, fungus and plants, in particular cereals (oat and barley). β-glucans are considered as GRAS and are currently used as texturing agents in the food industry. Alternative applications of β- glucan are the development of bio-based by using isolated β-glucan or in combination with other biopolymers. Objective: The aim of this work is to review all the potentiality that β-glucans present to develop bio-based films for food contact materials and medical applications. Results: It was very well described that the intake of β-glucan is related to the decrease of plasma cholesterol and stimulation of the immune system, depending on the β-glucan nature. However, during the last decade there has been an impressive grow on the interest on the development and use of bio-based films and packaging materials. Yeast cell wall, that consist of β-1,3-glucan network crosslinked to β-1,6-glucan, mannoprotein, and a small amount of chitin, are an attractive encapsulation matrix and for film forming preparations. In addition, dispersions of β-glucan from oat cultivars demonstrated to be promising films forming hydrogels, with potential to be used as biodegradable edible packaging film. Indeed, some investigations suggested the production of polysaccharide nanocrystals based on β-1,3-glucan from S. cerevisiae by using an esterification method. Conclusion: β-glucan was found to be a biopolymer with interesting features to be applied in materials science field, food contact and medical applications.