Muhammad Mujtaba

On chemistry of γ-chitin

The biological material, chitin, is present in nature in three allomorphic forms: α, β and γ. Whereas most studies have dealt with α- and β-chitin, only few investigations have focused on γ-chitin, whose structural and physicochemical properties have not been well delineated. In this study, chitin obtained for the first time from the cocoon of the moth (Orgyia dubia) was subjected to extensive physicochemical analyses and examined, in parallel, with α-chitin from exoskeleton of a freshwater crab and β-chitin from cuttlebone of the common cuttlefish. Our results, which are supported by13C CP-MAS NMR, XRD, FT-IR, Raman spectroscopy, TGA, DSC, SEM, AFM, chitinase digestive test and elemental analysis, verify the authenticity of γ-chitin. Further, quantum chemical calculations were conducted on all three allomorphic forms, and, together with our physicochemical analyses, demonstrate that γ-chitin is distinct, yet closer in structure to α-chitin than β-chitin.

Utilization of flax (Linum usitatissimum) cellulose nanocrystals as reinforcing material for chitosan films

Use of plastic based packaging tools is causing both health and economic problems. To overcome this situation, researchers are focusing on the use of different biomaterials such as chitosan and cellulose. The current study was conducted to check the effect of flax (Linum usitatissimum) cellulose nanocrystals (CNC) on mechanical and barrier properties of chitosan-based films. CNC was incorporated in different concentrations (5, 10, 20 and 30%). CNC was isolated from flax fiber using acid hydrolysis method. Tensile strength (TS) and young modulus (YM) values increased with the increase of CNC concentration. Chitosan film with 20% CNC revealed the highest YM value as 52.35MPa. No significant improvement was recorded in water vapor permeability due to overall lower film crystallinity. All the films were observed to be transparent up to an acceptable level. SEM and AFM analysis confirmed the homogeneity of films. A gradual enhancement was recorded in the antimicrobial activity of chitosan/CNC composite films. No significant improvement revealed in the thermal stability of composites.

Fluctuation in physicochemical properties of chitins extracted from different body parts of honeybee

It is well known that physicochemical properties of chitin are related with the extraction method. Recently, it was revealed that some physicochemical properties of chitin are also related with taxonomical relationship. For the first time in this study, it was tested how these properties of chitin are affected by different body parts of one organism. The chitins were extracted from five different body parts (head, thorax, abdomen, legs and wings) of honeybee. These chitins were physicochemically characterized and differences among these body parts were identified. Highest chitin content was observed in legs (13.25%) while the lowest from thorax (6.79%). The surface morphologies of the isolated chitin structures from five different body parts were analyzed with SEM, as a result, five different types of surface morphologies were recorded. However, three different types of surface morphologies were observed only in abdomen. Maximum degradation temperatures (DTG(max)) of thorax, abdomen, legs and wings were recorded between 359 and 367 °C while DTG(max) value of head chitin was found as 308 °C.

Novel three-dimensional cellulose produced from trunk of Astragalus gummifer (Fabaceae) tested for protein adsorption performance.

This is the first study to produce three-dimensional (3D) cellulose from any plant up to now. This 3D cellulose was produced from Astragalus gummifer(Fabaceae) trunk by using a modified method in which original the shape of cellulose was kept as natural. This novel 3D cellulose was characterized by SEM, TGA, FT-IR, XRD and elemental analysis to evidence the purity and to compare it with commercially available cellulose from cotton. Results from these characterizations were found convincing because almost the same physicochemical properties were observed for both newly obtained 3D cellulose and commercial one. Both fibers and pores on the surface of 3D cellulose were observed. Thanks to its diversified surface morphology, this novel 3D cellulose was tested for its protein adsorption performance and the results were compared with commercial cellulose as follows: maximum adsorption capacity at pH 8.0 was recorded as 59.2 mg/g for 3D cellulose while 29.6 mg/g for commercial cellulose. According to this result, it is clear to say that this sorbent has high affinity for lysozyme. Also this 3D cellulose could be useful for the other areas of separation science.

Changes in physicochemical properties of chitin at developmental stages (larvae, pupa and adult) of Vespa crabro (wasp)

It is already known that chitin in a single organism can exhibit huge differences depending on the functions it serves in different body parts, but the alterations in the characteristics of chitin in course of developmental stages of an organism still remain unknown. This study presents findings on how chitin matrix is changing physicochemically through discrete morphological stages - larva, pupa and adult - of an insect (Vespa crabro). Chitin content of the organisms were found to increase gradually as the organism grew; 2.1, 6.2 and 10.3%, with a dramatic increase in chitin deposition (nearly 3 folds) during the instar from larva to pupa. Enzymatic digestion test demonstrated that chitin isolates were close to pure. Chitin isolates were also subjected to thermal pyrolysis and no variations were observed in the thermal stability of the samples. However, it was observed that surface characteristics of chitin changed greatly as the insect grew.

Surface morphology of chitin highly related with the isolated body part of butterfly (Argynnis pandora)

This study was conducted to understand the differences in the physicochemical properties of chitin samples isolated from the wings and the other body parts except the wings (OBP) of a butterfly species (Argynnis pandora). The same isolation method was used for obtaining chitin specimens from both types of body parts. The chitin content of the wings (22%) was recorded as being much higher than the OBP (8%). The extracted chitin samples were characterized via FT-IR, TGA, XRD, SEM, and elemental analysis techniques. Results of these characterizations revealed that the chitins from both structures (wings and OBP) were very similar, except for their surface morphologies. SEM results demonstrated one type of surface morphology for the wings and four different surface morphologies for the OBP. Therefore, it can be hypothesized that the surface morphology of the chitin is highly related with the body part.

Diatomite as a novel composite ingredient for chitosan film with enhanced physicochemical properties

Practical applications of biopolymers in different industries are gaining considerable increase day by day. But still, these biopolymers lack important properties in order to meet the industrial demands. In the same regard, in the current study, chitosan composite films are produced by incorporating diatomite soil at two different concentrations. In order to obtain a homogeneous film, glutaraldehyde was supplemented to chitosan solution as a cross-linker. Compositing diatomaceous earth to chitosan film resulted in improvement of various important physicochemical properties compared to control such as; enhanced film wettability, increase elongation at break and improved thermal stability (264-277°C). The microstructure of the film was observed to haveconsisted of homogeneously distributed blister-shaped structures arised due to the incorporation of diatomite. The incorporation of diatomite did not influence the overall antioxidant activity of the composite films, which can be ascribe to the difficulty radicals formation. Chitosan film incorporated with increasing fraction of diatomite revealed a notable enhancement in the antimicrobial activity. Additionally with the present study, for the first time possible interactions between chitosan/diatomite were determined via quantum chemical calculations. Current study will be helpful in giving a new biotechnological perspective to diatom in terms of its successful application in hydrophobic composite film production.

An inclusive physicochemical comparison of natural and synthetic chitin films

Natural and synthetic chitin films, obtained from the same source were produced and their physicochemical properties were examined comparatively. Firstly, natural chitin film was obtained from elytra of an insect (Oryctes nasicornis L.) and purity of the obtained chitin film (degree of acetylation: 79±2%) was demonstrated by solid state 13C nuclear magnetic resonance (13C NMR). Then, the synthetic film was produced by dissolving of natural chitin film in LiCl-DMAc. The obtained natural and synthetic films were characterized by AFM, TGA, DSC, FTIR, mechanical properties, light transmission and contact angle. The analyses result demonstrated that natural chitin film lost very important properties such as high thermal stability, transparency, nanofibrous nature, tensile strength, Youngs modulus and hydrophobicity after transforming the synthetic film.

Newly isolated sporopollenin microcages from Platanus orientalis pollens as a vehicle for controlled drug delivery

Sporopollenin microcages were produced from the pollens of Platanus orientalis. Paracetamol was loaded into the microcages. Pollen, sporopollenin, paracetamol and paracetamol-loaded sporopollenin microcages were characterized with FT-IR, TGA and SEM. The analytical analyses demonstrated that sporopollenin microcages were structurally intact, highly reticulated and thermally stable. The loading efficiency of the sporopollenin microcages was found to be 8.2% using the passive loading technique and 23.7% via evaporating loading technique. In vitro release and kinetics studies were performed to test the suitability of sporopollenin microcages for loading. These studies revealed that sporopollenin from P. orientalis can be suggested as a suitable carrier for drug loading and controlled release studies.

Current advancements in chitosan-based film production for food technology; A review

Chitosan is obtained from chitin, which could be considered to be the most abundant polymer after cellulose. Owing to these properties, chitosan alone or chitosan-based composite film production is attaining huge attention in terms of applications from researchers and industrialists coming from divergent fields. To enhance the biological (mainly antimicrobial and antioxidant) and physiological (mainly mechanical, thermal and barrier) attributes of the chitosan-based films, a vast medley of plant extracts and supporting polymers has been blended into chitosan films. Considering the up to date literature reports based on chitosan film production and applications, it can be stated that still, the research ratio is low in this field. Chitosan blend/composite films with specific properties (superhydrophobicity, excellent mechanical strength, acceptable barrier properties) can be produced only for specific applications in food technology. In the current review, we tried to summarize the advancements made in the last 5-7 years in the field of chitosan film technology for its application in the food industry.