Research Outputs
Citrate-buffered Yamanaka medium allows to produce high-yield bacterial nanocellulose in static culture using Komagataeibacter strains isolated from apple cider vinegar
Bacterial nanocellulose (BNC) is a sustainable, renewable, and eco-friendly nanomaterial, which has gained great attentions in both academic and industrial fields. Two bacterial nanocellulose-producing strains (CVV and CVN) were isolated from apple vinegar sources, presenting high 16S rRNA gene sequence similarities (96%–98%) with Komagataeibacter species. The biofilm was characterized by scanning electron microscopy (SEM), revealing the presence of rod-shaped bacteria intricately embedded in the polymeric matrix composed of nanofibers of bacterial nanocellulose. FTIR spectrum and XRD pattern additionally confirmed the characteristic chemical structure associated with this material. The yields and productivities achieved during 10 days of fermentation were compared with Komagataeibacter xylinus ATCC 53524, resulting in low levels of BNC production. However, a remarkable increase in the BNC yield was achieved for CVV (690% increase) and CVN (750% increase) strains at day 6 of the fermentation upon adding 22 mM citrate buffer into the medium. This effect is mainly attributed to the buffering capacity of the modified Yakamana medium, which allowed to maintain pH close to 4.0 until day 6, though in combination with additional factors including stimulation of the gluconeogenesis pathway and citrate assimilation as a carbon source. In addition, the productivities determined for both isolated strains (0.850 and 0.917 g L−1 d−1) compare favorably to previous works, supporting current efforts to improve fermentation performance in static cultures and the feasibility of scaling-up BNC production in these systems.
Lanthanum-doped carbon dots for anticancer drug transport
Herein, we report lanthanum-doped carbon dots for delivering the anticancer drug camptothecin. The carbon dots are made as a nanocomposite with a β-cyclodextrin-polyethylene glycol-folate polymer. XRD shows a typical reflection of carbon dots (002). The size of the carbon dot composite is 10.19 nm. XPS shows peaks at 830 and 850 eV, characteristic of lanthanum doped in the carbon dots. The material is superparamagnetic with a saturation magnetization of 0.28 emu/g. The nanocomposite shows a broad absorption band with tail absorption in the near-infrared range. Further, the material shows a high camptothecin encapsulation efficiency above 90 % and a slow release for above 5 days. The in vitro anticancer effect of the drug-loaded nanocarrier is examined on MCF-7 cell lines, and the IC50 value is 1.92 µg mL− 1. The cell cycle arrest is analyzed using flow cytometry. The nanocarrier shows promising results as a drug delivery agent.
Toward biomanufacturing of next-generation bacterial nanocellulose (BNC)-based materials with tailored properties: A review on genetic engineering approaches
Bacterial nanocellulose (BNC) is a biopolymer that is drawing significant attention for a wide range of applications thanks to its unique structure and excellent properties, such as high purity, mechanical strength, high water holding capacity and biocompatibility. Nevertheless, the biomanufacturing of BNC is hindered due to its low yield, the instability of microbial strains and cost limitations that prevent it from being mass-produced on a large scale. Various approaches have been developed to address these problems by genetically modifying strains and to produce BNC-based biomaterials with added value. These works are summarized and discussed in the present article, which include the overexpression and knockout of genes related and not related with the nanocellulose biosynthetic operon, the application of synthetic biology approaches and CRISPR/Cas techniques to modulate BNC biosynthesis. Further discussion is provided on functionalized BNC-based biomaterials with tailored properties that are incorporated in-vivo during its biosynthesis using genetically modified strains either in single or co-culture systems (in-vivo manufacturing). This novel strategy holds potential to open the road toward cost-effective production processes and to find novel applications in a variety of technology and industrial fields.
Adsorbents Derived from Xylan Hemicellulose with Removal Properties of Pollutant Metals
The adsorption capacity of hydrogels derived from modified xylan hemicellulose has been tested in order to develop new bio-based adsorbent materials useful for removing metal ions pollutants, such as Cd(II), Cu(II) and Pb(II) from an aqueous solution. Xylan was extracted from bleached kraft pulp of eucalyptus and subsequently modified with different proportions of functional sulfonic acid groups (HA3–HA7) and sulfonate groups (HS30–HS70) to generate hydrogels. The results showed that all the synthesized hydrogels were capable of adsorbing metal ions, being the hydrogels with 30% and 50% xylan the ones that presented the highest adsorption capacity. Maximum capacity studies at different initial concentrations revealed that at an initial concentration of 300 mg·L−1, the HA3 hydrogel presented an adsorption capacity of 193 mg Pb(II), 182 mg Cd(II), and 66 mg Cu(II) per g hydrogel. The HA5 hydrogel presented a capacity of 185 mg Pb(II), 113 mg Cd(II), and 48 mg Cu(II) per g hydrogel. The HS30 hydrogel exhibited an adsorption of 205 mg Pb(II), 174 mg Cd(II), and 71 mg Cu(II) per g hydrogel, and HS50 hydrogel exhibited an adsorption capacity of 273 mg Pb(II), 143 mg Cd(II), and 45 mg Cu(II) per g hydrogel. These results show that modified Xylan hemicellulose is a promising adsorbent for removal Cd(II), Cu(II), and Pb(II) ions from aqueous solutions.
Hybrid nanomaterial composed of chitosan, curcumin, ZnO and TiO2 for antibacterial therapies
Metal nanoparticles have been tremendously utilised, such as; antibacterial and anticancer agents. Although metal nanoparticles exhibits antibacterial and anticancer activity, but the drawback of toxicity on normal cells limits their clinical applications. Therefore, improving the bioactivity of hybrid nanomaterial (HNM) and minimizing toxicity is of paramount importance for biomedical applications. Herein, a facile and simple double precipitation method was used to develop biocompatible and multifunctional HNM from antimicrobial chitosan, curcumin, ZnO and TiO2. In HNM, biomolecules chitosan and curcumin were used to control the toxicity of ZnO and TiO2 and improve their biocidal properties. The cytotxicological properties of the HNM was studied against human breast cancer (MDA-MB-231) and fibroblast (L929) cell lines. The antimicrobial activity of the HNM was examined against Escherichia coli and Staphylococcus aureus bacteria, via the well-diffusion method. In addition, the antioxidant property was evaluated by the radical scavenging method. These findings actively, support the ZTCC HNM potential, as an innovative biocidal agent for applications in the clinical and healthcare sectors.