Unveiling the mechanisms underlying photothermal efficiency of gold shell-isolated nanoparticles (AuSHINs) on ductal mammary carcinoma cells (BT-474)

Elucidating the toxicity of methyl parathion, imazapic, isoxaflutole, and chlorantraniliprole on human hepatocarcinoma cells and bioinspired membranes

Pesticides have boosted agricultural productivity but pose significant risks to environmental and human health. The intensification of agriculture has driven widespread pesticide use, with 66 % of global consumption allocated to sugarcane, soybean and corn. Sugarcane, a major monoculture in Brazil, India, and China, has driven a 700 % increase in pesticide use in Brazil over the past 40 years. Commonly used pesticides in Brazilian sugarcane farming include methyl parathion (PM), imazapic (IM), isoxaflutole (IS), and chlorantraniliprole (CL). Despite regulatory efforts by governmental agencies worldwide, the long-term toxicity of these substances on human health remains insufficiently studied. This study evaluates the cytotoxicity of PM, IM, IS, and CL at concentrations regulated by governmental agencies in human hepatocarcinoma (HepG2) cells. Given the liver's role in metabolizing xenobiotics, it is especially vulnerable to pesticide-toxicity. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and LDH (lactate dehydrogenase release) assays, alongside confocal microscopy, showed reduced cell viability and impaired membrane integrity, with progressive toxicity (from 24 to 96 h), primarily impacting mitochondrial activity. Surface pressure-area (π-A) isotherms, compressibility (CS⁻¹), and atomic force microscopy (AFM) revealed distinct pesticide incorporation mechanisms into Langmuir monolayers of HepG2 lipid extracts, used as membrane models. The findings underscore the hepatotoxicity of PM, IM, IS, and CL, even at concentrations regulated by governmental agencies, emphasizing their potential human health hazards.

Enhancing Photothermal Therapy Against Breast Cancer Cells by Modulating the End Point of Gold Shell-Isolated Nanoparticles Using Nanostraw-Assisted Injection

Gold shell-isolated nanoparticles (AuSHINs) are promising photothermal therapy (PTT) agents for cancer treatment due to their excellent photoconversion efficiency, biocompatibility, colloidal stability, and tunable properties, including size, shape, and surface functionalization. However, their therapeutic efficacy in in vitro assays is often limited by poor cellular uptake and lysosomal entrapment, which can result in nanoparticle degradation and a reduction in PTT effectiveness. In this study, we demonstrate that nanostraw-assisted injection enhances the PTT efficacy of AuSHINs compared to the conventional incubation method, as evaluated in human breast cancer cell lines: adenocarcinoma cells (MDA-MB-231) and glandular carcinoma cells (MCF7). This enhancement is attributed to three differences between the delivery methods: nanoparticle internalization, intracellular targeting, and the progression of cell death pathways. Nanostraw injection resulted in approximately 10-fold higher internalization of AuSHINs compared to 0.5-h incubation. Confocal fluorescence microscopy revealed that AuSHINs delivered via conventional incubation predominantly localize within lysosomes, whereas those introduced through nanostraw-assisted injection primarily targeted the endoplasmic reticulum (ER), thus avoiding lysosomal degradation. This differential targeting led to approximately a 2-fold higher reduction in the viability of photoactivated breast cancer cells treated with nanostraw-delivered AuSHINs. Furthermore, nanostraw-assisted injection accelerated the initiation of apoptosis relative to incubation. PTT-induced cell death was more pronounced in MCF7 cells compared to MDA-MB-231 cells, reflecting the higher resistance to therapy of the latter. These findings highlight the potential of nanostraw-assisted injection to enhance PTT, and we now face the challenge of integrating it into in vivo delivery strategies.

Single-particle adsorption of ultra-small gold nanoparticles at the biomembrane phase boundary

Nanomaterials are revolutionizing biomedical research by enabling the development of novel therapies, with applications ranging from drug delivery and diagnostics to the modulation of specific biological processes. Current research focuses on tasks such as enhancing cellular uptake of materials while preserving their functionality. However, the mechanisms governing interactions between nanomaterials and biological systems-particularly cellular membranes-remain challenging to elucidate due to the complex, dynamic nature of the lipid bilayer environment. This complexity arises from factors such as coexisting lipid domains (conserved regions of lipids) or lipid rafts, as well as cellular behaviors that induce state changes. The heterogeneous membrane landscape may offer unique adsorption properties and other functional effects, making it crucial to understand these interactions for greater biological control in nanotherapeutics. In this work, we systematically expose a phase-separated phospholipid-supported lipid bilayer (SLB)-specifically, a fluid-gel DOPC:DPPC bilayer-to low concentrations of citrate-capped 5 nm gold nanoparticles (AuNPs) to observe the adsorption process of individual AuNPs at the molecular scale. Using atomic force microscopy (AFM), we experimentally detect the adsorption of some AuNPs at the phase boundary. Complementary molecular dynamics (MD) simulations further elucidate the mechanism of single AuNP adsorption at lipid phase boundaries. Our findings indicate that the AuNP preferentially incorporates into the fluid-phase DOPC lipids while maintaining partial association with the gel-phase DPPC lipids due to diffusion effects. During adsorption, the AuNP disrupts lipid organization by increasing lateral lipid mixing across the phase boundary. This disruption to lipid molecular ordering is further evident upon AuNP incorporation into the bilayer. The ability to modulate the spatial organization and structure of lipid molecules has significant implications for therapeutics that leverage lipid diffusion pathways for alternative drug delivery mechanisms or to induce specific lipid behaviors.

Baicalein Interactions with Lipid Membrane Models: Implications for Its Protective Role against Respiratory Viral Infections

Flavonoids are known for their antioxidant, anti-inflammatory, antitumoral, and antiviral properties, as is the case for baicalein derived from the roots of Scutellaria baicalensis, which is effective against respiratory viral infections. In this study, we investigate the molecular mechanisms underlying the interaction between baicalein and Langmuir monolayers as models for cell membranes. For comparison, we analyzed monolayers from lipid extracts of two cell lines: oropharyngeal carcinoma (HEp-2), which is susceptible to respiratory viral infections, and primary melanoma (A375), which is not. Baicalein incorporation into A375 lipid extract monolayers shifted the π-A isotherms to larger areas, reducing monolayer stability. In contrast, its incorporation into HEp-2 lipid extract monolayers shifted the π-A isotherms to smaller areas, enhancing both compaction and stability. Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) revealed that baicalein interactions with A375 lipid extracts involved electrostatic attractions and repulsions with choline and phosphate headgroups, disrupting chain organization and expanding the monolayer. In HEp-2 lipid extracts, baicalein interacted strongly with phosphate headgroups and lipid chains, increasing chain order and stabilizing the monolayer. These findings suggest that baicalein stabilizes HEp-2 lipid membranes, potentially providing a protective mechanism against respiratory viral infections. Its selective interaction with lipid membranes is consistent with its therapeutic potential and role in modulating membrane properties to inhibit viral entry.

Photoactivated Rose Bengal Triggers Phospholipid Hydroperoxidation and Late Apoptosis in Colorectal Cancer Cells

Rose Bengal (RB) is a promising photosensitizer (PS) for photodynamic therapy (PDT), but its application to colorectal carcinoma remains largely unexplored. Herein, we employ in vitro assays to demonstrate that incorporation of RB has substantial phototoxicity against Caco-2 cells, with more than 80% reduction in cell viability for 24 h incubation with 5 × 10-6 mol/L RB followed by irradiation. In contrast, RB had minimal toxicity without irradiation. The mechanisms of RB action were further elucidated using confocal fluorescence microscopy, Langmuir monolayers as cell membrane models, and flow cytometry to determine the cell death pathways. Flow cytometry revealed that the primary mode of cell death was late apoptosis. RB incorporation affected Caco-2 plasma membrane morphology under light irradiation, and membrane interactions were confirmed using Langmuir monolayers of Caco-2 lipid extracts. Incorporation of RB into the monolayers shifted the pressure-area isotherms toward larger molecular areas, especially at low surface pressures and increasing RB concentrations (1, 10, and 25 × 10-6 mol/L). RB adsorption also caused a decrease in the in-plane elasticity (Cs1-) of the Caco-2 monolayers, with a large increase in monolayer flexibility as RB concentration increased. According to polarization-modulated infrared reflection absorption spectroscopy (PM-IRRAS), the anionic RB interacted electrostatically with positively charged phospholipid groups. Moreover, the changes in surface area observed in the monolayers upon RB incorporation and irradiation could be attributed to hydroperoxidation reactions triggered by the generation of singlet oxygen (1O2). These findings indicate that RB may be used as a PS in the PDT of colorectal cancer, providing detailed insights into its mechanism of action and phototoxicity.

Designing Gold Nanoparticles for Precise Glioma Treatment: Challenges and Alternatives

Glioblastoma multiforme (GBM) is a glioma and the most aggressive type of brain tumor with a dismal average survival time, despite the standard of care. One promising alternative therapy is boron neutron capture therapy (BNCT), which is a noninvasive therapy for treating locally invasive malignant tumors, such as glioma. BNCT involves boron-10 isotope capturing neutrons to form boron-11, which then releases radiation directly into tumor cells with minimal damage to healthy tissues. This therapy lacks clinically approved targeted blood-brain-barrier-permeating delivery vehicles for the central nervous system (CNS) entry of therapeutic boron-10. Gold nanoparticles (GNPs) are selective and effective drug-delivery vehicles because of their desirable properties, facile synthesis, and biocompatibility. This review discusses biomedical/therapeutic applications of GNPs as a drug delivery vehicle, with an emphasis on their potential for carrying therapeutic drugs, imaging agents, and GBM-targeting antibodies/peptides for treating glioma. The constraints of GNP therapeutic efficacy and biosafety are discussed.