No abstract

Proteinaceous materials have numerous structures, many of which aid in the roles they perform. Some need to impart strength while others need elasticity or toughness. This study is the first to investigate the modification of both globular and fibrous protein, namely, zein, soy protein and gelatin, using deep eutectic solvents (DES) to form bioplastics, which may have application in drug delivery systems. The effects of DES content on the thermal and mechanical properties of the material were determined. Zein and soy are globular proteins, which both showed a significant change in the properties by the addition of DES. Both of these materials were, however, weaker and less ductile than the starch based materials previously reported in the literature. The material made from gelatin, a fibrous protein, showed variable properties depending on how long they were in contact with each other before pressing. Conductivity and NMR measurements indicate the existence of a continuous liquid phase, which are useful in the demonstrated application of transdermal drug delivery systems. It is shown that pharmaceutical DESs can be gelled with gelatin and this method is three times faster at delivering a pharmaceutical active ingredient across the skin barrier than from a corresponding solid formulation.

Polyolefin based plastics are extensively used for packaging applications and as such they tend to have a short service life but they have a long environmental persistence. One strategy to accelerate the mechanical degradation of polyolefin plastics in the environment is to blend them with carbohydrate based polymers. Unfortunately polyolefins are hydrophobic whereas carbohydrates tend to be hydrophilic so the two do not blend without chemical modification of the carbohydrate. In this study high density polyethylene, HDPE and thermoplastic starch, TPS are used as the polymers with deep eutectic solvents, DESs as the modifiers. Both TPS and DESs are biodegradable and the DESs are water miscible and biocompatible ensuring that the composite plastic contains a biodegradable flaw which should enable mechanical and chemical degradation. It is shown that DESs enable facile mixing of the two polymers. The composite has a strength similar to TPS but a ductility greater than either of the two components. The glass transition temperature of the composite plastic shows that they are homogeneously mixed and data suggests that the DESs act as lubricants rather than plasticisers. Fig. 6 Mechanical analysis of m-HDPE:TPS blends (BBbefore boiling and ABafter boiling) (a) UTS (b) elongation at break (c) stress-strain curves.This journal is

Deep eutectic solvent (DES) is a class of ionic liquids, consisting of a mixture generally formed by combining hydrogen bond donors (HBDs) such as alcohols, amides and carboxylic acids with various quaternary ammonium salts. The decrease in melting points of the constituents is due to the charge delocalization during formation of hydrogen bonding between the hydrogen bond acceptor with the hydrogen bond donor. This can be considered one of the main reasons for increasing solubility and absorption of DESs. Most active pharmaceutical ingredients (APIs) have polar functional groups containing amide, carboxylic acid, alcohol or quaternary ammonium groups. These tend to increase the melting point of the compounds, but they can be used to form eutectic mixtures. While this concept has previously used, the combination of quaternary ammonium salts with amides, carboxylic acids and alcohols can result in large depressions of freezing points and so-called deep eutectic solvents are formed. DESs mix readily with water and so could increase the uptake of APIs. In this study, pharmaceutical deep eutectic solvents (PDESs) are formulated from 3 APIs: imipramine HCl, ascorbic acid and catechol. These PDESs were used to plasticise gelatine. It is shown that the materials formed can be used to increase the rate of API uptake via both oral and transdermal delivery modes. Thus, the concentration of the PDESs in solution reaches the maximum before the pure drugs. Particularly for catechol, after 1 s, the dissolution of the PDESs was more than twice that of the pure drug. Moreover, the transdermal delivery mode uptake of the PDES based on imipramine HCl from the patch after 15 min was found to be 65% compared with just imipramine HCl which released only 20%. Graphical abstract

No abstract