• Biodegradable PBAT/PLA blend with bioactive MCPA-PHBV conjugate suppresses weed growth

      Kwiecień, Iwona; Adamus, Grazyna; Jiang, Guozhan; Radecka, Iza; Baldwin, Timothy C.; Khan, Habib R.; Johnston, Brian; Pennetta, Valentina; Hill, David; Bretz, Inna; et al. (ACS Paragon Plus Environment, 2017-12-20)
      The herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) conjugated with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was prepared via a melt transesterification route. The resultant bioactive oligomer was then mixed with a blend of polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) with different loadings; to manufacture films to be used as a bioactive, biodegradable mulch to deliver the herbicide to target broadleaf weed species. The biological targeting of the MCPA-PHBV conjugate in the mulch film was investigated under glasshouse conditions using faba bean (Vicia faba) as a selective (non-target) model crop species having broadleaf morphology. The presence of the MCPA-PHBV conjugate in the biodegradable PBTA/PLA blend was shown to completely suppress the growth of broadleaf weed species, whilst displaying only a mild effect on the growth of the model crop. The degradation of the mulch film under glasshouse conditions was quite slow. The release of the MCPA-PHBV during this process was detected using NMR, GPC, EDS and DSC analyses, indicating that the majority of the MCPA diffused out after MCPA-PHBV conjugate bond scission. These data provide a strong “proof of concept” and show that this biodegradable, bioactive film is a good candidate for future field applications and may be of wide agricultural applicability.
    • Synthesis of silver nanoparticles using curcumin-cyclodextrins loaded into bacterial cellulose based hydrogels for wound dressing applications

      Gupta, Abhishek; Briffa, Sophie M; Swingler, Sam; Gibson, Hazel; Kannappan, Vinodh; Adamus, Grazyna; Kowalczuk, Marek M; Martin, Claire; Radecka, Iza (American Chemical Society (ACS), 2020-01-22)
      Chronic wounds are often recalcitrant to treatment due to high microbial bioburden and the problem of microbial resistance. Silver is a broad spectrum natural antimicrobial agent with wide applications extending to proprietary wound dressings. Recently silver nanoparticles have attracted attention in wound management. In the current study, the green synthesis of nanoparticles was accomplished using a natural reducing agent, curcumin which is a natural polyphenolic compound, well known as a wound healing agent. The hydrophobicity of curcumin was overcome by its microencapsulation in cyclodextrins. This prediction study demonstrates the production, characterisation of silver nanoparticles using aqueous curcumin:hydroxypropyl-β-cyclodextrin complex and loading them into bacterial cellulose hydrogel with moist wound healing properties. These silver nanoparticle-loaded bacterial cellulose hydrogels were characterised for wound management applications. In addition to high cytocompatibility, these novel dressings exhibited antimicrobial activity against three representative wound infecting pathogenic microbes Staphylococcus aureus, Pseudomonas. aeruginosa and Candida auris.
    • Tailoring the supramolecular structure of guanidinylated pullulan toward enhanced genetic photodynamic therapy

      Zhou, Jie; Mohamed Wali, Aisha Roshan; Ma, Shengnan; He, Yiyan; Yue, Dong; Tang, James Zhenggui; Gu, Zhongwei (ACS Publications, 2018-04-24)
      In the progress of designing a gene carrier system, what is urgently needed is a balance of excellent safety and satisfactory efficiency. Herein, a straightforward and versatile synthesis of a cationic guanidine-decorated dendronized pullulan (OGG3P) for efficient genetic photodynamic therapy was proposed. OGG3P was able to block the mobility of DNA from a weight ratio of 2. However, G3P lacking guanidine residues could not block DNA migration until at a weight ratio of 15, revealing guanidination could facilitate DNA condensation via specific guanidinium-phosphate interactions. A zeta potential plateau (∼+23 mV) of OGG3P complexes indicated the nonionic hydrophilic hydroxyl groups in pullulan might neutralize the excessive detrimental cationic charges. There was no obvious cytotoxicity and hemolysis, but also enhancement of transfection efficiency with regard to OGG3P in comparison with that of native G3P in Hela and HEK293T cells. More importantly, we found that the uptake efficiency in Hela cells between OGG3P and G3P complexes was not markedly different. However, guanidination caused changes in uptake pathway and led to macropinocytosis pathway, which may be a crucial reason for improved transfection efficiency. After introducing a therapeutic pKillerRed-mem plasmid, OGG3P complexes achieved significantly enhanced KillerRed protein expression and ROS production under irradiation. ROS-induced cancer cells proliferation suppression was also confirmed. This study highlights the guanidine-decorated dendronized pullulan could emerge as a reliable nonviral gene carrier to specifically deliver therapeutic genes.