Enhancing Photothermal Therapy Against Breast Cancer Cells by Modulating the End Point of Gold Shell-Isolated Nanoparticles Using Nanostraw-Assisted Injection Sabrina A. Camacho, Pedro H. B. Aoki, Frida Ekstrand, Osvaldo N. Oliveira, Christelle N. Prinz ACS Applied Materials and Interfaces, 2025 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.
Baicalein Interactions with Lipid Membrane Models: Implications for Its Protective Role against Respiratory Viral Infections Bruna Alves Martins, Giovanna Eller Silva Sousa, Alexandre Mendes de Almeida, Karina Alves Toledo, Osvaldo N. Oliveira, et al. Langmuir, 2025 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 André Satoshi Ferreira, Alexandre Mendes de Almeida Junior, Mirella Boaro Kobal, Lucas Gontijo Moreira, Sabrina Aléssio Camacho, et al. Langmuir, 2025 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.
Determining Molecular-Level Interactions of Carboxyl-Functionalized Nanodiamonds with Bacterial Membrane Models as the Basis for Antimicrobial Activity Giovanna Eller Silva Sousa, Bruna Alves Martins, Alexandre Mendes de Almeida Junior, Rafaela Campos Queiroz, Dayane Batista Tada, et al. Langmuir, 2025 Carbon-based nanostructures, such as carboxylated nanodiamonds (NDCOOHs), are promising to combat resistant bacterial strains by targeting their protective membranes. Understanding their interactions with bacterial membranes is therefore important for elucidating the mechanisms underlying NDCOOHs antimicrobial activity. In this study, we investigated the incorporation of NDCOOHs into lipid Langmuir monolayers mimicking cytoplasmic membranes of Escherichia coli and Staphylococcus aureus, model systems for Gram-negative and Gram-positive bacteria, respectively. Using polarization-modulated infrared reflection-absorption spectroscopy (PM-IRRAS), we observed significant interactions between NDCOOHs and the polar head groups of the E. coli lipid monolayer, driven by electrostatic attraction to ammonium groups and repulsion from phosphate and carbonyl ester groups, limiting deeper penetration into the lipid chains. In contrast, S. aureus monolayers exhibited more pronounced changes in their hydrocarbon chains, indicating deeper NDCOOHs penetration. NDCOOHs incorporation increased the surface area of the E. coli monolayer by approximately 4% and reduced that of S. aureus by about 8%, changes likely attributed to lipid oxidation induced by superoxide and/or hydroxyl radicals generated by NDCOOHs. These findings highlight the distinct interactions of NDCOOHs with Gram-positive and Gram-negative lipid membranes, offering valuable insights for their development as targeted antimicrobial agents.
Enhancing Phototoxicity in Human Colorectal Tumor Cells Through Nanoarchitectonics for Synergistic Photothermal and Photodynamic Therapies Alexandre Mendes de Almeida Junior, André Satoshi Ferreira, Sabrina Aléssio Camacho, Lucas Gontijo Moreira, Karina Alves de Toledo, et al. ACS Applied Materials and Interfaces, 2024 Phototherapies are promising for noninvasive treatment of aggressive tumors, especially when combining heat induction and oxidative processes. Herein, we show enhanced phototoxicity of gold shell-isolated nanorods conjugated with toluidine blue-O (AuSHINRs@TBO) against human colorectal tumor cells (Caco-2) with synergic effects of photothermal (PTT) and photodynamic therapies (PDT). Mitochondrial metabolic activity tests (MTT) performed on Caco-2 cell cultures indicated a photothermal effect from AuSHINRs owing to enhanced light absorption from the localized surface plasmon resonance (LSPR). The phototoxicity against Caco-2 cells was further increased with AuSHINRs@TBO where oxidative processes, such as hydroperoxidation, were also present, leading to a cell viability reduction from 85.5 to 39.0%. The molecular-level mechanisms responsible for these effects were investigated on bioinspired tumor membranes using Langmuir monolayers of Caco-2 lipid extract. Polarization-modulation infrared reflection-absorption spectroscopy (PM-IRRAS) revealed that the AuSHINRs@TBO incorporation is due to attractive electrostatic interactions with negatively charged groups of the Caco-2 lipid extract, resulting in the expansion of surface pressure isotherms. Upon irradiation, Caco-2 lipid extract monolayers containing AuSHINRs@TBO (1:1 v/v) exhibited ca. 1.0% increase in surface area. This is attributed to the generation of reactive oxygen species (ROS) and their interaction with Caco-2 lipid extract monolayers, leading to hydroperoxide formation. The oxidative effects are facilitated by AuSHINRs@TBO penetration into the polar groups of the extract, allowing oxidative reactions with carbon chain unsaturations. These mechanisms are consistent with findings from confocal fluorescence microscopy, where the Caco-2 plasma membrane was the primary site of the cell death induction process.
Application in hyperthermia treatment Sabrina A. Camacho, J.J. Hernández-Sarria, Josino Villela S. Neto, M. Montañez-Molina, F. Muñoz-Muñoz, et al. Silicon Based Hybrid Nanoparticles Fundamentals Properties and Applications, 2021
