Porous antimicrobial crosslinked film of hydroxypropyl methylcellulose/carboxymethyl starch incorporating gallic acid for wound dressing application.

Because of weak mechanical qualities and low degree of swelling of hydroxypropyl methylcellulose/carboxymethyl starch (HP/CMS) blended films for wound dressing application, this work prepared a unique antimicrobial crosslinked film utilizing succinic acid (SA) as a non-toxic crosslinker and gallic acid (GAL) as an antibacterial agent. It was observed that the infrared-shifted peak position of OH stretching and bending in HP/CMS/SA/GAL films was caused by hydrogen bond formation among HP, CMS and GAL components. The antimicrobial crosslinked films considerably enhanced their mechanical properties and swelling degree. After adding SA and GAL, the films retained their porosity structure as observed by scanning electron images. Moreover, GAL-loaded HP/CMS/SA films could inhibit Staphylococcus aureus and Escherichia coli growth, showing their wound dressing potential. Crystallinity percentage, water vapor transmission rate, gel fraction, water solubility, water uptake and cytotoxicity were also investigated.

Hydroxypropyl methylcellulose/carboxymethyl starch/zinc oxide porous nanocomposite films for wound dressing application.

Because of low moisture uptake, water vapor transmission rate, oxygen transmission rate, swelling capacity and no antibacterial activity of hydroxypropyl methylcellulose (HPMC) film, carboxymethyl starch (CMS) and zinc oxide nanoparticles (ZnO-NPs) were incorporated in order to improve its limitations for wound dressing application. The infrared shifted peak of OH stretching and OH bending in HPMC/CMS blended films was detected due to hydrogen bond formation between HPMC and CMS. Scanning electron images of HPMC/CMS blended films exhibited porous structure. In addition, swelling degree, moisture uptake, water vapor transmission rate and oxygen transmission rate of HPMC/CMS blended films with various contents of CMS clearly increased compared to HPMC film. Moreover, HPMC/CMS nanocomposite films loaded with ZnO-NPs showed good antibacterial activity against Staphylococcus aureus and Escherichia coli, revealing their potential for wound dressing application. Percentage of crystallinity, cytotoxicity, mechanical and thermal properties were also examined.

Characterization and properties of singly and dually modified hydrogen peroxide oxidized and glutaraldehyde crosslinked biodegradable starch films.

Poor properties of native cassava starch film such as low mechanical properties and high water uptake are the limitations of biodegradable starch films. Dual modification is an alternative way to improve the properties. Characteristics and properties of oxidized, crosslinked and dually modified starch films by hydrogen peroxide oxidation and glutaraldehyde crosslinking were examined. Sequence of the dual modification was also studied. All starch films were prepared by casting technique using glycerol plasticizer. The oxidation and crosslinking of modified starch were confirmed by carbonyl and carboxyl contents as well as degree of crosslinking. The lowest and highest molecular weights of the modified starch were observed for the oxidized starch and crosslinked starch, respectively. Moreover, swelling power and moisture absorption of dually modified starch films was clearly lower than those of singly modified films. Additionally, both good stiffness and extensibility was also obtained from the dually modified films especially for the crosslinked-oxidized film. Moreover, thermal property and biodegradability were also determined.

Property improvement of biodegradable citric acid-crosslinked rice starch films by calcium oxide.

Due to several important limitations for packaging applications of starch film such as strength and hydrophilicity, rice starch (Oryza sativa) film was crosslinked with citric acid and modified by different contents of calcium oxide. FTIR spectra showed the evidence of crosslinking by citric acid and the presence of calcium oxide in the modified rice starch films. After the crosslinking, the decrease of degree of crystallinity and swelling including the increase of film smoothness and strain at maximum load were observed. The application of both citric acid and calcium oxide caused greater decrease of swelling, moisture uptake as well as higher stiffness and antibacterial activity than those of the use of only the citric acid. The highest stiffness and antibacterial activity were found for the crosslinked film added by 5 wt% calcium oxide. Moreover, the effect of calcium oxide contents on morphological, thermal and biodegradable properties of the crosslinked films was also investigated.

Property improvement of antibacterial wound dressing from basil seed (O. basilicum L.) mucilage- ZnO nanocomposite by borax crosslinking.

Some applications, in particular, wound dressings, require significant water holding capability: hydrogels formed from Basil seed mucilage (BSM) are non-toxic natural substances and exhibit the needed water holding capacity. However, the sponges have low dimensional stability and easily degrade in aqueous media. We overcame this drawback by crosslinking with borax. To provide antibacterial activity, zinc oxide nanoparticles (ZnO-NP) were added. With 10-20 wt% added borax and ZnO-NP, all key properties improved: dimensional stability, water retention capacity (31 to 41%), stress at maximum load (2.6 to 6.6 MPa), Young's modulus (74 to 113 MPa) and strain (28 to 54%). An interconnecting system of pores with well distributed ZnO-NP was observed from scanning electron microscope. In addition, higher borax and ZnO-NP loadings slightly decreased porosity (92% to 73%) and swelling (109 to 56). Moreover, antibacterial activity and cytotoxicity of BSM hydrogel sponge were also examined.

Development, modification and characterization of new biodegradable film from basil seed (Ocimum basilicum L.) mucilage.

BACKGROUND: Biodegradable films from basil seed mucilage (BSM) were formed and modified with several di-carboxylic acid crosslinkers; i.e. tartaric acid (TA), malic acid (MA) and succinic acid (SA) with varying acidity and chemical structures, to enhance mechanical properties and water barrier ability. Basil seeds have a reasonable mucilage content and valuable properties; thus, it has the potential to develop valuable new biodegradable films. RESULT: We characterized BSM films with the three crosslinkers using Fourier-transform infrared (FTIR) spectra and observed a 1730 cm-1 CO stretching peak, which confirmed ester linkage between the mucilage and crosslinkers. The crosslinked films showed higher gel fraction than native films. The crosslinked films showed better swelling and water vapor permeability with SA than with TA and MA. Crosslinking led to significant improvement in strain at maximum load. Further, the stress maximum load was comparable to that of commercial low-density polyethylene (LDPE) film. Crosslinked films showed additional homogeneous morphology and an increase in thermal degradation temperatures. CONCLUSION: Crosslinking with dicarboxylic acids improved all the key properties of BSM films, including excellent stress and strain at maximum load, improved barrier capability and thermal properties. Thus, these films showed good potential as biodegradable films, especially for food packaging. © 2019 Society of Chemical Industry.

Characterization of an antibacterial wound dressing from basil seed (Ocimum basilicum L.) mucilage-ZnO nanocomposite.

The large water holding capacity of Basil Seed (Ocimum basilicum L.) Mucilage (BSM) gives it potential to produce a valuable polymer for water holding applications such as wound dressing. The objective of this research was to prepare a natural-based antibacterial wound dressing from BSM by freeze-drying. Various contents of zinc oxide nanoparticles (ZnO-NP) were incorporated as an antibacterial agent. BSM hydrogel sponge showed considerable porosity and degree of swelling. From FTIR analysis, hydrogen bond and electrostatic interaction between BSM molecules and ZnO-NP were confirmed. SEM images revealed an interconnecting open-cell structure of pores in the BSM hydrogel sponge with a good distribution of ZnO-NP. Moreover, increase in ZnO-NP content improved the mechanical properties (stress at maximum load 8.9 MPa, Young's modulus 151 MPa and strain at maximum load 51%), thermal properties, water retention capacity and antibacterial activity. Cytotoxicity and cell adhesion studies of BSM hydrogel sponge indicated non-cytotoxicity and non-adherent nature of the sponge.

Characterization and properties of biodegradable thermoplastic grafted starch films by different contents of methacrylic acid.

Due to poor mechanical and thermal properties of native starch (NS) film; in the present work; NS was modified by graft copolymerization. Thermoplastic starch (TPS) grafted by methacrylic acid (MAA) with different percentage of grafting, i.e., 0%, 18.3%, 36.3%, 52.1% and 89.7% were prepared and tested. The result demonstrated that the intensity of IR peak of acrylic group increased with the increasing percentage of grafting. The higher graft copolymerization with MAA also significantly reduced degree of crystallinity. The strain at maximum load of TPS film grafted by MAA increased with the increasing percentage of grafting. However, water uptake of TPS film grafted by MAA reduced with high percentage of grafting (52.1% and 89.7%). In addition, different TPS films grafted by MAA were also examined for morphology, water vapor permeability, thermal property and biodegradable property by soil buried test.

Effect of dual modification on properties of biodegradable crosslinked-oxidized starch and oxidized-crosslinked starch films.

Due to poor properties of biodegradable native starch (NS) film; in this work, dual-modified starch films i.e. crosslinked-oxidized starch (C-OS) and oxidized-crosslinked starch (O-CS) films were prepared and compared to single-modified starch i.e. crosslinked starch (CS) and oxidized starch (OS) films. All modified starch films were oxidized and crosslinked using hydrogen peroxide and boric acid by casting technique. Degree of crystallinity and swelling behavior of both dual-modified starch films were found to decrease. Moreover, O-CS film showed smoother fractured morphology than C-OS and NS films. Both C-OS and O-CS films presented not only high stress at maximum load and Young's modulus but also high strain at maximum load, as compared to single-modified film. Furthermore, water vapor permeability, thermal property and biodegradability of all modified films were also studied.

The effect of thai glutinous rice starch on the synthesis of lead zirconate (PbZrO3) nanofibers via the electrospinning method.

This study synthesized blended lead zirconate (PbZrO3;PZ)/poly(ethylene oxide)(PEO)/Glutinous rice starch (GRS) nanofibers by the electrospinning method. A number of parameters such as the ratio between PEO and GRS and calcination temperature have been studied. The as-spun PZ/PEO/GRS composite and PZ fibers were characterized by TG-DTA, X-ray diffraction, FT-IR and SEM, respectively. SEM results showed that smooth and continuous fibers were obtained at the volume ratio of 10:2:1, PZ/PEO/GRS. After calcination of the as-spun PZ/PEO/GRS composite nanofibers at 650 degrees C for 4 h, PZ nanofibers with perovskite structure were obtained successfully. The fibers had a uniform and smooth surface without grain boundaries. However, when the calcination temperature increased to 750 degrees C and 850 degrees C, the fiber represented a necklace-like structure with grain boundaries arranged by grain to grain unit cell clusters.