Yu Yue Qin

Physical Properties and Antibacterial Activity of a Chitosan Film Incorporated with Lavender Essential Oil

Chitosan-based films containing lavender essential oil (LEO) (0, 0.5%, 1.0%, 1.5% (v/v)) were prepared to evaluate their physical and antibacterial activities. In order to study the impact of the incorporation of LEO into chitosan matrix, the solubility, mechanical property, water vapor permeability, and antibacterial activity of the films were investigated. Fourier transform infrared chromatography (FTIR) was carried out to explain structure–property relationships. Results showed that the solubility and water vapor permeability of the chitosan-based film decreased by LEO incorporation. Films containing LEO showed better mechanical property. FTIR spectra demonstrated good interaction between functional groups of chitosan with LEO. With the concentration of LEO increased from 0 to 1.5 %, the inhibitory zone of four bacterial strains (Escherichia coli, Staphylococcus aurous, Bacillus magaterium, Bacillus subtilis) increased. It can be concluded that chitosan films containing LEO can be used for development of active food packaging materials.

Characterization of Antioxidant Chitosan Film Incorporated with Pomegranate Peel Extract

A novel antioxidant chitosan film incorporated with pomegranate peel extract (PPE) (0, 1%, 2%, and 3% (w/v)) was developed. The mechanical property, water vapor permeability, total phenolic content and antioxidant activity of the films were investigated. Fourier transform infrared (FTIR) spectra revealed that good interactions occurred between functional groups of chitosan with PPE. The flexibility and water vapor barrier property were improved by incorporation with PPE. Films containing PPE had higher total phenolic content and showed better antioxidant activity. These results suggest that chitosan films incorporated with PPE can be useful for meat preservation.

Physical Properties and Antimicrobial Activity of a Poly(Lactic Acid)/Poly(Trimethylene Carbonate) Film Incorporated with Thymol

Thymol (TH), which has antimicrobial effect on many food pathogens, was incorporated as antimicrobial agent into composite poly (lactic acid)/poly (trimethylene carbonate)(PLA-PTMC) films. Antimicrobial active films based on PLA-PTMC were prepared by incorporating thymol at five different concentrations: 0, 3, 6, 9 and 12 %(w/w). The mechanical characterization, water vapor permeability (WVP), and antimicrobial activity of all formulations composite film were carried out. A decrease in elastic modulus was obtained for the active composite film compared with neat PLA-PTMC film. The presence of thymol decreased water vapor permeability, with a significant antimicrobial activity. Antimicrobial activities of films were tested against Escherichia coli, Staphylococcus aurous, Listeria, Bacillus subtilis, and Salmonella. Increasing amount of the thymol in the film caused a significant increase in inhibitory zones. These results suggest that thymol incorporated PLA-PTMC films have a prospectively potential in antimicrobial food packaging.

Preparation and Characterization of poly(L-lactide) /poly (ε-caprolactone) Composite Films for Food Packaging Application

Poly (L-lactide) (PLLA) and poly (ε-caprolactone) (PCL) were produced by solution mixing and cast into films. The films were characterized by morphological, mechanical, and barrier behavior tests to evaluate the effect of the PCL. The micrographs of the fractured surfaces showed the morphology of the phase separated system, with the dispersed PCL phase higher than 30%. The elongation at break of PLLA was improved significantly (p<0.05) in the blends while the tensile strength decreased significantly (p<0.05) with increase of PCL content. WVP of PLLA/PCL films significantly decreased (p < 0.05) by blending with PCL. When the ratio of PLLA/PCL increased from 100/0 to 50/50, WVP of PLLA/PCL films decreased from 1.85±0.15 (×10-14 kgm/m2sPa) to 1.27±0.06 (×10-14 kgm/m2sPa). The results showed that PLLA/PCL blend can be a novel composite film for food packaging applications.

Preparation and Characterization of Poly(L-Lactide-Co-ε-Caprolactone) Copolymer for Food Packaging Application

Biodegradable poly (L-lactide-co-ε-caprolactone) (PLA-PCL) copolymers were synthesized via solution polymerization by varying the feed composition of L-lactide (LLA) and ε-caprolactone (ε-CL) (LLA/ ε-CL= 1/0, 1/1, 1/2, and 1/3). PLA-PCL film was produced by solution mixing. The films were characterized by thermal property, mechanical property, and barrier behavior tests to evaluate the effect of the PCL. The differential scanning calorimetry analyses revealed the micro-domain structure in the copolymer. The elongation at break of PLLA was improved significantly (p<0.05) in PLA-PCL copolymer while the tensile strength decreased significantly (p<0.05) with increase of PCL content. WVP of PLA-PCL films significantly decreased (p< 0.05) when compared with that of neat PLLA film. When the feed ratio of PLA-PCL copolymer increased from 1/0 to 1/3, WVP of PLA-PCL films increased from 1.85±0.15 (×10-11 gm/m2sPa) to 2.83±0.26 (×10-11 gm/m2sPa). The results showed that PLA-PCL copolymer can be a novel film for food packaging applications.

Physical Properties and Antimicrobial Activity of a Poly(lactic acid)/poly(ε-caprolactone) Film Antimicrobial Coating with Chitosan

In this work a preliminary study on the physical properties and antimicrobial activity of environmentally friendly active films to be produced is presented. Chitosan (CH), which has antimicrobial effect on many food pathogens, was coated as antimicrobial agent into composite poly (lactic acid)/poly (ε-caprolactone)(PLA-PCL) films. Antimicrobial active films based on PLA-PCL were prepared by coating five different chitosan concentrations: 0, 2, 4, 6 and 8 %(w/w). The mechanical characterization, water vapor permeability (WVP), and antimicrobial activity of composite PLA-PCL film coating with chitosan were carried out. The mechanical characterization, water vapor permeability of composite PLA-PCL films coating with chitosan was uninfluenced. Antimicrobial activities of films were tested against Staphylococcus aurous, Escherichia coli, Bacillus subtilis, Listeria, Salmonella. The antimicrobial activity of films were significantly increase with the chitosan concentration. The results of this work suggest that chitosan coated composite PLA-PCL films have a prospectively potential in antimicrobial activity food packaging.

Synthesis of Poly(ethylene glycol) Derivatives

To expand the extent of conjugation with biologically active molecules (biopolymers, peptides, drugs, etc.) and biomaterial substrates, we synthesized a serial of poly (ethy1ene glycol) (PEG) derivatives (PEG-2000-NH2, MPEG-1200-NH2, and APEG-1200-NH2) in three efficient steps. The end groups were characterized by 1H NMR spectroscopy.

Preparation and Structure Characterization of Poly(lactide-co-ethylene carbonate) Microspheres

The purpose of this study was to prepare and characterize tinidazole-loaded poly (lactide-co-ethylene carbonate) (PLEC) microspheres. These biodegradable microspheres were prepared by solvent evaporation method. The effect of selected emulsifier, polymer type, and ratio of tinidazole to PLEC were investigated. An aqueous gelatin solution used as emulsifier resulted in uniform microspheres with spherical surfaces. The PLEC microspheres exhibited rough surface and porous internal structures when compared with the PLA microspheres. The ratio of tinidazole to PLEC (1/10) exhibited higher encapsulation efficiency and drug loading of tinidazole. The introduction of hydrophilic PEC content influenced the structure and encapsulation efficiency of microspheres. These results suggest that the novel PLEC microspheres can be useful for drug delivery systems.

Synthesis and Characterization of CdSe Nanocrystal Quantum Dots by Solution-Liquid-Solid Method

The present work describes a solution-liquid-solid (SLS) synthesis route for the preparation of CdSe nanocrystal quantum dots using the low-melting-point Bi nanoparticles as catalysts. UV-vis absorption spectra were used to determine the growth of CdSe cluster. The shape and size distribution of the CdSe QDs were determined by analysis of Transmission electron microcopy (TEM) images. A peak wavelength of 399nm in the absorption spectra on day 5 indicated that the CdSe cluster formed. TEM micrographs showed that CdSe QDs had a relatively narrow distribution of QD size, and the diameter of CdSe QDs was about 4 nm. Our preliminary results illustrated that smaller size of CdSe QDs could be prepared by SLS method and it was small enough for bioimaging applications.

Modified Octyl-2-Cyanoacrylate Tissue Adhesive for the Closure of Long Surgical Incisions

Long surgical incisions required application of more flexible cyanoacrylate adhesive to relieve skin tension. A new formulation of octyl-2-cyanoacrylate (OCA) was modified by 0%, 3%, 6% and 9% (w/v) polytrimethylene carbonate (PTMC). The OCA/PTMC adhesives showed higher viscosity and bond strength than OCA monomer. The OCA/6% PTMC adhesive plus subcutaneous suture was used as group A (Treatment group), and the OCA/6% PTMC tissue adhesive alone was used as group B (Control group). 30 days later, there was no apparent scar formation in group A. A linear scar formation still could be seen in group B. The results supported the use of OCA/6% PTMC adhesive alone or adhesive plus subcutaneous suture in long surgical incisions, and the latter maintained better scar formation.