Curcumin- and quercetin-functionalized polypropylene membranes as active food packaging material

A wide range of active agents, synthetic and natural agents such as essential oils, chitosan and polyphneols consisting of curcumin, gallic acid, anthocyanins, and catechins have been used in order to develop antimicrobial packaging systems, and among them, natural polyphenolic compounds, specially curcumin (Cur) has great potential due to effective biological activities in developing food packaging material. Quercetin (Quer) is also the mostly studied flavonol as a color-changing indicator in the food industry and has been already developed as a realistic alternative for smart and active food packaging. The reason for choosing these two polyphenolic compounds is that they simultaneously possess many beneficial properties such as antioxidant, antibacterial, antiviral, antitumoral, and anti-inflammatory effects. Additionally, the main objective of the study is to combine polypropylene (PP), which is the most preferred and cost-effective polymer in the packaging industry, with these active ingredients, rather than using more expensive polymer types. In this context, PP-Quer or PP-Cur membranes, which are new experiences based on these literatures were chemically characterized by Fourier transform infrared spectroscopy, and the surface morphology of these composite membranes was characterized by scanning electron microscopy. The antibacterial response against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria species was investigated. Furthermore, the reactive oxygen species generation and anticancer activity of these composite membranes using human colorectal adenocarcinoma (HT-29) were observed. We proposed that PP-Quer or PP-Cur composite membranes can be a potential candidate as active packaging material in the food industry.

Advances in surface properties characterization and modification for lignin

Renewed interests on lignin and its derivatives have led to increasingly more investigations due to the problems in environmental impact while with the great reuse possibilities for producing them-based new and advanced materials to reduce the petroleum achieving sustainable development. The related studies have shown more integrated database on the surface properties characterization and modification of those renewable materials. Based on numerous works did at our group and others reported elsewhere, this review covers the surface properties of lignin and its derivatives in relation to various methods and theories. In this work, the progress on the recent developments of advanced methods for lignin surface characterization and modification are also documented. Of this review, a perspective is finally presented.

Magnesium (Mg2 +), Strontium (Sr2 +), and Zinc (Zn2 +) Co-substituted Bone Cements Based on Nano-hydroxyapatite/Monetite for Bone Regeneration

New bone cement type that combines Sr2 + /Mg2 + or Sr2 + /Zn2 + co-substituted nano-hydroxyapatite (n-HAs) with calcium phosphate dibasic and chitosan/gelatin polymers was developed to increase adhesion and cellular response. The cements were physicochemically described and tested in vitro using cell cultures. All cements exhibited quite hydrophilic and had high washout resistance. Cement releases Ca2 + , Mg2 + , Sr2 + , and Zn2 + in concentrations that are suitable for osteoblast proliferation and development. All of the cements stimulated cell proliferation in fibroblasts, endothelial cells, and osteoblasts, were non-cytotoxic, and produced apatite. Cements containing co-substituted n-HAs had excellent cytocompatibility, which improved osteoblast adhesion and cell proliferation. These cements had osteoinductive potential, stimulating extracellular matrix (ECM) mineralization and differentiation of MC3T3-E1 cells by increasing ALP and NO production. The ions Ca2 + , Mg2 + , Zn2 + , and Sr2 + appear to cooperate in promoting osteoblast function. The C3 cement (HA-SrMg5%), which was made up of n-HA co-substituted with 5 mol% Sr and 5 mol% Mg, showed exceptional osteoinductive capacity in terms of bone regeneration, indicating that this new bone cement could be a promising material for bone replacement.

Antimicrobial Light-Activated Polypropylene Modified with Chitosan: Characterization and Reusability

Chitosan is a polycationic structure and an inherent antimicrobial compound. Through reactive blending, a robust and stable light-activated antimicrobial plastic that is also reusable was prepared. The antimicrobial plastic (PP-MVE-CHI) was challenged against Escherichia coli K12 while simultaneously being exposed to UV-A light for 30 min. The antimicrobial plastic retained its antimicrobial efficacy for 10 cycles, providing 94.0 ± 3.3% reduction in the microbial population across the 10 cycles. Infrared spectroscopy confirmed marginal effect on the surface chemistry after the 10 cycles. Fluorometric evaluations suggested that the antimicrobial effect was driven by reactive oxygen species generation. No evidence of fouling on the material was found through microscopic techniques. In addition, electron microscopy analysis on the bacteria exposed to this material under UV-A suggested damage to cell morphology.

Variation in Cell Surface Hydrophobicity among Cryptococcus neoformans Strains Influences Interactions with Amoebas

Cryptococcus neoformans and Cryptococcus gattii are pathogenic fungi that cause significant morbidity and mortality. Cell surface hydrophobicity (CSH) is a biophysical parameter that influences the adhesion of fungal cells or spores to biotic and abiotic surfaces. C. neoformans is encased by polysaccharide capsule that is highly hydrophilic and is a critical determinant of virulence. In this study, we report large differences in the CSH of some C. neoformans and C. gattii strains. The capsular polysaccharides of C. neoformans strains differ in repeating motifs and therefore vary in the number of hydroxyl groups, which, along with higher-order structure of the capsule, may contribute to the variation in hydrophobicity that we observed. We found that cell wall composition, in the context of chitin-chitosan content, does not influence CSH. For C. neoformans, CSH correlated with phagocytosis by natural soil predator Acanthamoeba castellanii Furthermore, capsular binding of the protective antibody (18B7), but not the nonprotective antibody (13F1), altered the CSH of C. neoformans strains. Variability in CSH could be an important characteristic in comparing the biological properties of cryptococcal strains.IMPORTANCE The interaction of a microbial cell with its environment is influenced by the biophysical properties of a cell. The affinity of the cell surface for water, defined by the cell surface hydrophobicity (CSH), is a biophysical parameter that varies among different strains of Cryptococcus neoformans The CSH influences the phagocytosis of the yeast by its natural predator in the soil, the amoeba. Studying variation in biophysical properties like CSH gives us insight into the dynamic host-predator interaction and host-pathogen interaction in a damage-response framework.

Local and controlled release of tamoxifen from multi (layer-by-layer) alginate/chitosan complex systems

Herein, multilayer polysaccharide films were proposed and characterized as biomaterials for the local and controlled release of an antitumoral drug. To that aim, multilayer films of alginate (Alg) and chitosan (Chi) were built up through spray assisted layer-by-layer (LbL) technique employing an automatic equipment. A specific drug against breast cancer, tamoxifen (TMX), was incorporated in different intermediate positions of the multilayer Alg/Chi films. Our findings highlight that Alg/Chi multilayer films can be employed for sustained and local TMX delivery and their therapeutic effect can be modulated and optimized by the number of bilayers deposited over the loaded tamoxifen, the quantity of tamoxifen loaded in several intermediate positions and the total area of the film.

Review of Electrochemically Triggered Macromolecular Film Buildup Processes and Their Biomedical Applications

Macromolecular coatings play an important role in many technological areas, ranging from the car industry to biosensors. Among the different coating technologies, electrochemically triggered processes are extremely powerful because they allow in particular spatial confinement of the film buildup up to the micrometer scale on microelectrodes. Here, we review the latest advances in the field of electrochemically triggered macromolecular film buildup processes performed in aqueous solutions. All these processes will be discussed and related to their several applications such as corrosion prevention, biosensors, antimicrobial coatings, drug-release, barrier properties and cell encapsulation. Special emphasis will be put on applications in the rapidly growing field of biosensors. Using polymers or proteins, the electrochemical buildup of the films can result from a local change of macromolecules solubility, self-assembly of polyelectrolytes through electrostatic/ionic interactions or covalent cross-linking between different macromolecules. The assembly process can be in one step or performed step-by-step based on an electrical trigger affecting directly the interacting macromolecules or generating ionic species.

Effect of the incorporation of chitosan on the physico-chemical, mechanical properties and biological activity on a mixture of polycaprolactone and polyurethanes obtained from castor oil

In the present study, polyurethane materials were obtained from castor oil, polycaprolactone and isophorone diisocyanate by incorporating different concentrations of chitosan (0.5, 1.0 and 2.0% w/w) as an additive to improve the mechanical properties and the biological activity of polyurethanes. The polyurethanes were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, stress/strain fracture tests and swelling analysis, and the hydrophilic character of the surface was determined by contact angle trials. The objectives of the study were to evaluate the effect of the incorporation of chitosan on the changes of the physico-chemical and mechanical properties and the in vitro biological activity of the polyurethanes. It was found that the incorporation of chitosan enhances the ultimate tensile strength of the polyurethanes and does not affect the strain at fracture in polyurethanes with 5% w/w of polycaprolactone and concentrations of chitosan ranging from 0 to 2% w/w. In addition, PCL5-Q-PU formulations and their degradation products did not affect cell viability of L929 mouse fibroblast and 3T3, respectively. Polyurethane formulations showed antibacterial activities against Staphylococcus aureus and Escherichia coli bacteria. The results of this study have highlighted the potential biomedical application of this polyurethanes related to soft and cardiovascular tissues.

Chitosan functionalisation of gold nanoparticles encourages particle uptake and induces cytotoxicity and pro-inflammatory conditions in phagocytic cells, as well as enhancing particle interactions with serum components

Background

Gold nanoparticles (AuNPs) are a popular choice for use in medical and biomedical research applications. With suitable functionalisation AuNPs can be applied in drug delivery systems, or can aid in disease diagnosis. One such functionalisation is with chitosan, which enables efficient interaction and permeation of cellular membranes, providing an effective adjuvant. As both AuNPs and chitosan have been shown to have low toxicity and high biocompatibility their proposed use in nanomedicine, either individually or combined, is expanding. However, further toxicological and immunological assessments of AuNP-chitosan conjugates are still needed. Therefore, we have evaluated how AuNP functionalisation with chitosan can affect uptake, cytotoxicity, and immunological responses within mononuclear cells, and influence the interaction of AuNPs with biomolecules within a complex biofluid. The AuNPs used were negatively charged through citrate-coating, or presented either low or high positive charge through chitosan-functionalisation. Uptake by THP-1 cells was assessed via transmission electron microscopy and electron energy loss spectroscopy, pro-inflammatory responses by ELISA and qRT-PCR, and cell death and viability via lactate dehydrogenase release and mitochondrial activity, respectively. Interactions of AuNPs with protein components of a frequently used in vitro cell culture medium supplement, foetal calf serum, were investigated using mass spectrometry.

Results

Although cells internalised all AuNPs, uptake rates and specific routes of intracellular trafficking were dependent upon chitosan-functionalisation. Accordingly, an enhanced immune response was found to be chitosan-functionalisation-dependent, in the form of CCL2, IL-1β, TNF-α and IL-6 secretion, and expression of IL-1β and NLRP3 mRNA. A corresponding increase in cytotoxicity was found in response to chitosan-coated AuNPs. Furthermore, chitosan-functionalisation was shown to induce an increase in unique proteins associating with these highly charged AuNPs.

Conclusions

It can be concluded that functionalisation of AuNPs with the perceived non-toxic biocompatible molecule chitosan at a high density can elicit functionalisation-dependent intracellular trafficking mechanisms and provoke strong pro-inflammatory conditions, and that a high affinity of these NP-conjugates for biomolecules may be implicit in these cellular responses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-015-0146-9) contains supplementary material, which is available to authorized users.

Controlled formation of barium fluoride nanocrystals by electric-assisted phase separation and precipitation

This work demonstrated that barium fluoride (BaF₂) nanocrystals can be controllably formed by an electric-assisted phase separation and precipitation method, EAPSP, in a water/ethanol mixture.