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INTERNATIONAL CONGRESS OF

CancerGenetics

• Chitosan-Functionalized Niosomes as a Dual-Action Delivery System for Spirulina maxima: Targeting Drug-Resistant Bacteria and Colorectal Cancer Cells

• Sepideh Asadi,^1,* Saeedeh Hosseini,² Maryam Jafari,³ Fatemeh Ashrafi,⁴ Pooria Moulavi,⁵
  1. Department of Pathobiology, Faculty of Veterinary Medicine, Amol University of Special Modern Technologies, Amol, Iran.
  2. Department of Fisheries, Faculty of Natural Resources, University of Tehran, Karaj, Iran.
  3. Department of Microbiology and Immunology, Faculty of Veterinary Medicine, University of Tehran, Tehran, Iran
  4. Department of Biology, North Tehran Branch, Islamic Azad University, Tehran, Iran.
  5. Department of Biology, North Tehran Branch, Islamic Azad University, Tehran, Iran.
  
  
  
• Introduction: The growing prevalence of multidrug-resistant (MDR) bacterial strains and the limited effectiveness of conventional cancer treatments have necessitated the development of innovative therapeutic strategies. One such approach involves using nanoscale drug delivery systems that enhance the bioavailability, stability, and targeted delivery of therapeutic agents. Niosomes, vesicular nanocarriers composed of non-ionic surfactants, offer advantages such as biocompatibility, sustained drug release, and the ability to encapsulate both hydrophilic and hydrophobic molecules. Nevertheless, their performance can be further improved through surface functionalization. Spirulina maxima, a cyanobacterial species rich in bioactive compounds, has demonstrated diverse therapeutic properties, including antioxidant, antimicrobial, and anticancer activities. However, its clinical application is limited by poor bioavailability and rapid degradation in physiological conditions. To overcome these limitations, this study developed a chitosan-coated niosomal system (Nio-maxima@CS) loaded with S. maxima extract. The aim was to evaluate the antibacterial activity of the formulation against carbapenem-resistant Klebsiella pneumoniae (CRKP) and its anticancer efficacy against colorectal cancer (HT-29) cells.
• Methods: Niosomes were prepared using the thin-film hydration method with a 1:1 ratio of Span 60 and Tween 60 as surfactants. After hydration with S. maxima extract and sonication for 7 minutes, the vesicles were coated with 0.1% chitosan to enhance their stability and biological activity. The formulations were characterized by dynamic light scattering (DLS) for particle size and zeta potential, and transmission electron microscopy (TEM) for morphological analysis. Entrapment efficiency (EE%) was measured spectrophotometrically. Drug release studies were performed over 72 hours using a dialysis bag method in PBS (pH 7.4). Antibacterial activity was tested against CRKP using broth microdilution for minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), as well as crystal violet staining to assess biofilm inhibition. Gene expression of ampC, blaKPC, and fimH was analyzed via quantitative PCR. For anticancer studies, MTT assays were performed to assess cytotoxicity in HT-29 cells and normal fibroblasts. Apoptosis was evaluated by measuring the expression levels of Bax, Bcl-2, p53, and caspase-3. Intracellular reactive oxygen species (ROS) and nitric oxide (NO) levels were also quantified using standard fluorescent probes.
• Results: The uncoated and chitosan-coated niosomes exhibited average sizes of 120.7 nm and 135.7 nm, respectively. TEM images confirmed spherical morphology and uniform distribution. Entrapment efficiency increased from 73.9% in Nio-maxima to 77.2% in Nio-maxima@CS. Chitosan coating contributed to enhanced stability and reduced burst release; after 72 hours, cumulative release was 42% for Nio-maxima@CS compared to 51.5% for uncoated vesicles. Nio-maxima@CS demonstrated enhanced antibacterial activity against CRKP, with MIC and MBC values 8-fold and 4-fold lower, respectively, than the free extract. Additionally, it inhibited biofilm formation by approximately 75%. Gene expression analysis revealed significant downregulation of ampC, blaKPC, and fimH, suggesting suppression of resistance and biofilm-related mechanisms. In cytotoxicity assays, Nio-maxima@CS reduced the viability of HT-29 cells in a time- and dose-dependent manner, with an IC50 of 21.37 µg/mL at 72 hours, while maintaining low toxicity in normal fibroblasts. Apoptotic gene profiling showed increased expression of pro-apoptotic Bax (4.21-fold) and p53 (4.4-fold), decreased anti-apoptotic Bcl-2 (0.44-fold), and elevated caspase-3 levels (4.7-fold). ROS production rose to 169.3% compared to control, accompanied by a marked increase in NO levels, indicating oxidative stress as a key mediator of apoptosis.
• Conclusion: The chitosan-coated niosomal delivery system significantly enhanced the antibacterial and anticancer efficacy of S. maxima extract. Nio-maxima@CS effectively suppressed CRKP growth and biofilm formation, downregulated key resistance genes, and induced selective apoptosis in colorectal cancer cells via ROS and caspase pathways. These findings support the potential of functionalized niosomes as dual-action nanocarriers for combating MDR infections and colorectal cancer. Further in vivo studies are warranted to validate clinical applicability.
• Keywords: Chitosan-coated niosomes, Spirulina maxima, Antibacterial drug delivery, Carbapenem-resistant Klebsi