Gold nanoparticles on superfluid droplets illuminate century-old ‘Thomson problem’
Technique could be expanded to control self organization The post Gold nanoparticles on superfluid droplets illuminate century-old ‘Thomson problem’ appeared first on Physics World .
Gold nanoparticles (AuNPs) have shown great potential for photothermal therapy (PTT) in cancer treatment, but their clinical application is limited by systemic toxicity and poor deep-tissue penetration. This study presents a sustainable and biocompatible bio-hybrid platform that utilizes the probiotic E. coli Nissle 1917 (EcN) to create AuNPs through an eco-friendly intracellular green chemistry method.
EcN cultures were grown in Luria-Bertani (LB) medium and exposed to a 1 mM chloroauric acid (HAuCl4) metallic precursor. A room-temperature green synthesis protocol used ascorbic acid (Vitamin C) as a non-toxic co-reductant to induce seed-mediated crystallization of AuNPs onto the bacterial interior.
The resulting bio-hybrid system (EcN::AuNPs) was characterized through visual inspection, UV-Vis spectroscopy, and in vitro PTT assays under continuous-wave near-infrared (NIR) laser irradiation. Upon visual examination, the AuNPs exhibited a deep dark-brownish hue due to the reduction of Au3+ to Au0. UV-Vis spectroscopy confirmed the formation of stabilized, isotropic gold nanostructures (30-60nm) with a broadened surface plasmon resonance (SPR) band at 560nm, which is indicative of the enhanced localization of electromagnetic fields.
Biocompatibility tests showed that the EcN::AuNPs platform caused a significant decrease in cell viability, from 10^8CFU/mL to 10^3CFU/mL, due to trivalent gold heavy-metal toxicity, mechanical disruption of the bacterial cell wall, and metabolic/oxidative stress. However, the surviving bacterial population retained chemotactic capabilities necessary for targeting tumors.
When exposed to 5 minutes of continuous NIR laser irradiation, the EcN::AuNPs bio-hybrid platform demonstrated exceptional concentration-dependent hyperthermia kinetics, causing a thermal increase from 20°C to an absolute peak of 75.4°C. This performance outperformed all control groups (pure EcN, bare HAuCl4, and standalone ascorbic acid).
The engineered EcN::AuNPs bio-hybrid platform represents a promising alternative for targeted oncological interventions, offering a balance between active biological tumor targeting and rapid, localized photothermal ablation while maintaining biosafety and biocompatibility.
Written by urgent.news from bioRxiv's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
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