Eco – Friendly Synthesis of Ag / Tio 2 Nanoparticles Using Beta Vulgaris Leaf Extract and Their Biomedical Applications

Technical Summary: Eco-Friendly Synthesis of Ag/TiO₂ Nanoparticles Using Beta vulgaris Leaf Extract and Their Biomedical Applications

Problem Statement
The study addresses two critical challenges: the environmental persistence of pharmaceutical contaminants, specifically diclofenac sodium (DCF), and the need for sustainable, non-toxic methods for synthesizing advanced nanomaterials. DCF is a widely used non-steroidal anti-inflammatory drug (NSAID) that resists conventional wastewater treatment, leading to its accumulation in aquatic ecosystems and causing ecological harm, including endocrine disruption in aquatic life and population declines in vultures. While Advanced Oxidation Processes (AOPs) like the Fenton process offer degradation solutions, they often rely on unstable reagents like hydrogen peroxide. Concurrently, the synthesis of metal oxide nanocomposites typically involves hazardous chemicals. This research proposes a "green" alternative: synthesizing Silver-doped Titanium Dioxide (Ag/TiO₂) nanoparticles using Beta vulgaris (beetroot) leaf extract to create an eco-friendly photocatalyst for drug degradation and a multifunctional agent for biomedical applications.

Methodology
The researchers employed a green synthesis protocol where fresh Beta vulgaris leaves were washed, shade-dried, ground into powder, and used as a reducing and capping agent to synthesize Ag/TiO₂ nanoparticles. The resulting nanohybrids were comprehensively characterized using:

• Morphological and Structural Analysis: Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS) and elemental mapping, Transmission Electron Microscopy (TEM), and X-ray Diffraction (XRD).
• Physical and Spectral Characterization: Dynamic Light Scattering (DLS) for particle size distribution, Fourier Transform Infrared (FT-IR) spectroscopy for functional groups, and UV-Vis spectroscopy for optical properties.
• Photocatalytic Degradation: The degradation of diclofenac sodium was assessed under UV-Vis light irradiation using the synthesized Ag/TiO₂ nanocomposite. Kinetic studies were performed to determine reaction rates, and the influence of pH (2.5 to 10.5) was evaluated.
• Biomedical Assays:
  • Cytotoxicity and Anticancer Activity: Evaluated via MTT assay on normal Vero cells and human breast cancer (MCF-7) cell lines.
  • Antioxidant Activity: Measured using the DPPH radical scavenging assay.
  • Antimicrobial Activity: Tested against four bacterial strains (Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa) and two fungal strains (Candida albicans, Trichoderma viride) using the disc diffusion method.

Key Results

• Synthesis and Characterization: The green synthesis successfully produced Ag/TiO₂ nanohybrids. SEM and TEM analyses revealed a mixed morphology of spherical, rod-shaped, and cauliflower-like structures with particle sizes ranging from 8 to 60 nm (with some aggregation up to >100 nm). XRD confirmed a face-centered cubic structure with an average crystallite size of approximately 36 nm. Elemental mapping confirmed the homogeneous distribution of Ag, Ti, and O, along with phytochemical elements (K, Cl, S, P, Si) from the leaf extract.
• Photocatalytic Degradation: The Ag/TiO₂ nanocomposite demonstrated high efficiency in degrading diclofenac sodium. Under UV-Vis irradiation, approximately 90% to 98% degradation was achieved within 40 minutes. The degradation followed pseudo-first-order kinetics. The process was most effective under acidic conditions (pH 2.5), where electrostatic attraction between the positively charged catalyst surface and neutral drug molecules facilitated adsorption and radical generation.
• Biomedical Applications:
  • Anticancer Activity: The nanoparticles exhibited concentration-dependent cytotoxicity. Against MCF-7 breast cancer cells, viability dropped to 24.78% at 1000 µg/mL, with an IC₅₀ value of approximately 31.2 µg/mL. Normal Vero cells showed higher viability (54.06% at 1000 µg/mL), suggesting selective toxicity toward cancer cells.
  • Antioxidant Activity: The nanoparticles showed significant DPPH radical scavenging activity, reaching 82.91% inhibition at 1000 µg/mL.
  • Antimicrobial Activity: The nanocomposites displayed strong, concentration-dependent antibacterial activity, particularly against Bacillus cereus (18 mm inhibition zone at 1000 mg/mL) and Pseudomonas spp. (15 mm). However, antifungal activity against Candida albicans and Trichoderma viride was comparatively weak and showed little variation with concentration.

Significance and Claims
The paper claims that the study successfully demonstrates a simple, cost-effective, and eco-friendly method for synthesizing Ag/TiO₂ nanoparticles using plant extracts, eliminating the need for hazardous chemical reagents. The synthesized nanomaterials are presented as multifunctional agents with promising applications in:

1. Environmental Remediation: Effective degradation of persistent pharmaceutical pollutants like diclofenac sodium from aqueous environments.
2. Biomedical Research: Potential use as an anticancer agent against breast cancer cells, an antioxidant, and an antibacterial agent.

The authors conclude that while the nanoparticles show significant potential, further in vivo studies and mechanistic investigations are required to confirm their therapeutic efficacy and safety before clinical application. The work positions green-synthesized Ag/TiO₂ as a viable candidate for future drug delivery systems, pharmaceutical formulations, and environmental treatment technologies.