Volume 88, Issue 9

CD44, a cell-surface glycoprotein, plays an important role in cell proliferation, adhesion, migration, and other biological functions, which are related with the physiological and pathologic activities of cells. Especially, CD44 is extensively expressed within adult bone marrow and has been considered as an important marker for some cancer stem cells (CSCs) in various types of tumors. Therefore, it is essential to understand the variations in CD44 expression of stem cells and cancer cells for further clinical applications. In this paper, CD44 expression was assessed on a human colon cancer cell line (SW620), a human mesenchymal stem-like cell line (3A6), and a human foreskin fibroblast line (Hs68). We used chitosan to establish a suspension culture model to develop multicellular spheroids to mimic a three-dimension (3D) in vivo environment. Obviously, CD44 expression on 3A6 and SW620 cells was dynamic and diverse when they were in the aggregated state suspended on chitosan, while Hs68 cells were relatively stable. Furthermore, we discuss how to regulate CD44 expression of 3A6 and SW620 cells by the interactions between cell and cell, cell and chitosan, as well as cell and microenvironment. Finally, the possible mechanism of chitosan to control CD44 expression of cells is proposed, which may lead to the careful use of chitosan for potential clinical applications.

Chitosan-based coating (M4F2) was used successfully to delay ripening and prolong shelf-life of rapidly perishable and expensive Alphonso mango fruits stored at 30 ± 3°C and 40–50% RH for 15 days. Matured raw Alphonso mango fruits were simple dip treated/coated and air dried with our newly developed chitosan based formulation (for industry) with additives. Samples were taken at regular intervals for routine analysis of fruits. Results indicated that M4F2 coating could decrease the decay incidence loss along with delay the change in color of mango fruit during storage but not physiological steady weight loss. Interestingly, sensory evaluation indicated that quality of mango was enhanced slight significantly to more sweetness and better aroma by M4F2 coating compared to uncoated control fruits. Further, our M4F2 coating formulation may act as an important potentiator of flavor compounds of mango as well as controlling organic acids and sugars, which are key components in the perception of mango flavor. Understanding the chemical components that contribute to flavor perception of the fruit is necessary for post-harvest storage technology. This information is also important to study chitosan/derivatives elicitation in molecular level to improve mango flavor as well as in identification of genes responsible for flavor quality. The scientific story behind this effective chitosan based coating formulation development has been discussed.

Chito-oligosaccharides (COSs) are a substance class of high interest due to various beneficial bioactive properties. However, detailed mechanistic and application-related investigations are limited due to the poor availability of COSs with defined structural properties. Here, we present the large-scale production of COSs with defined degree of N-acetylation using a commercial cellulase preparation from Trichoderma longibrachiatum . The enzyme preparation was found to exclusively produce COSs lacking of acetyl groups while MS/MS analysis indicated a cellobiohydrolase to be the responsible for hydrolysis with the enzyme preparation. MS and NMR analysis proved the low content of acetyl groups in the COS mix and oligomers with a degree of polymerization (DP) of 2–6 were obtained. The low cost enzyme source was further exploited for large-scale production in a 20 g batch and resulted a COSs yield of 40%. An inexpensive enzyme source for the production of bioactive COSs was successfully implemented and thorough product analysis resulted in well-defined COSs. This strategy could improve the access to this substance class for a more detailed investigation of its various biological activities.

Hydrolysis of natural chitin and chitosans was performed in the electron beam plasma (EBP) of oxygen, by means of specially designed electron beam plasmachemical reactor (EBPR). Low molecular water-soluble chitin oligosaccharides with weight-average molecular mass 800–2000 Da and polydispersion index 1.5–2.5 were produced due to action of active oxygen species formed in the EBP. By optimizing the treatment conditions the 95% yield of chitin oligosaccharides was obtained after 2 min whereas the conventional chemical hydrolysis usually takes several days. The studies of the antimicrobial activity of low molecular products formed due to EBP-stimulated degradation showed that they inhibit the multiplication of various mycelial and yeast-like fungi. The technique involved is likely to be promising for the production of bioactive low molecular chitin oligosaccharides and the EBP-stimulated hydrolysis appears to be competitive with technologies conventionally used in the industry.

The use of biostimulants to enhance crop productivity is beginning to be adopted into mainstream agricultural practice. There is an emerging consensus on the critical role that low-cost and scalable chitosan oligosaccharide production systems can play in meeting the demands of this “greener” approach in agriculture. The objective of our research was to produce chitosan oligosaccharides (CHOS) mixtures that can work as plant biostimulants using cost effective enzymes. Commercial chitosans with a consistent formulation and available in bulk were used in the study. Chitosans were characterized in terms of degree of N-acetylation (pH-metric titration) and molecular weight (Ubbelohde viscometer). The yield of the CHOS were determined along with their physicochemical characteristics. The biological activity of the different CHOS mixtures were evaluated for efficacy against a fungal pathogen ( F. oxysporum ) in the susceptible tomato cultivar ‘Moneymaker’. The performance of some CHOS resulted in significant enhancements in a number of plant health indicators such as increased biomass, disease control and induction of ISR markers. Finally, the optimal CHOS preparation in terms of plant bioactivity was scaled up and validated by a preliminary field trial with the industrial tomato cultivar ‘H9661’. The effectiveness of this treatment on crop productivity was consistent with the results observed in the lab and similar to other commercial plant biostimulants.

Cibacron brilliant red 3B-A (CBR) has been introduced to determine chitosan (CS) concentrations in solution, and several studies applied it to measure chitosan content in pharmaceutical formulations. So far, studies have relied on the absorbance band shift to 570 nm to determine the extent of the CBR – CS interaction. In this study, we show that CBR forms micro- to nanometer sized aggregates with CS, depending on their charge ratio and that other photophysical changes in CBR are induced by this interaction. We found that, besides the bathochromic band shift, aggregation induces emission at 600 nm and emission quenching at 360 nm. We compared changes CS induced in absorbance and fluorescence emission of CBR with the CS monomer glucosamine and poly(allylamine) hydrochloride, which both contain amino groups, and found that similar but less intense photophysical changes also occur. Furthermore, CS-induced circular dichroism in CBR suggests a twisted, chiral structure of these aggregates that should match with the previously published in silico simulations of the structure of CS in solution. The low linear charge density of CS and its chiral conformation are considered responsible for the enhanced photophysical response of CBR interacting with the polycation.

Novel hybrid hydrogels were formed by adding chitosan (Ch) to phospholipids (P) self-assembled particles in lactic acid. The effect of the phospholipid concentration on the hydrogel properties was investigated and was observed to affect the rate of hydrogel formation and viscoelastic properties. A lower concentration of phospholipids (0.5% wt/v) in the mixture, facilitates faster network formation as observed by Dynamic Light Scattering, with lower elastic modulus than the hydrogels formed with higher phospholipid content. The nano-porous structure of Ch/P hydrogels, with a diameter of 260±20 nm, as observed by cryo-scanning electron microscopy, facilitated the penetration of water and swelling. Cell studies revealed suitable biocompatibility of the Ch/P hydrogels that can be used within life sciences applications.