Thermal effects and biological response of breast and pancreatic cancer cells undergoing gold nanorod-assisted photothermal therapy.

To increase the therapeutic efficacy of nanoparticle (NP)-assisted photothermal therapy (PTT) and allow for a transition toward the clinical setting, it is pivotal to characterize the thermal effect induced in cancer cells and correlate it with the cell biological response, namely cell viability and cell death pathways. This study quantitatively evaluated the effects of gold nanorod (GNR)-assisted near-infrared (NIR) PTT on two different cancer cell lines, the 4T1 triple-negative breast cancer cells and the Pan02 pancreatic cancer cells. The interaction between nanomaterials and biological matrices was investigated in terms of GNR internalization and effect on cell viability at different GNR concentrations. GNR-mediated PTT was executed on both cell lines, at the same treatment settings to allow a straightforward comparison, and real-time monitored through thermographic imaging. A thermal analysis based on various parameters (i.e., maximum absolute temperature, maximum temperature change, temperature variation profile, area under the time-temperature change curve, effective thermal enhancement (ETE), and time constants) was performed to evaluate the treatment thermal outcome. While GNR treatment and NIR laser irradiation alone did not cause cell toxicity in the selected settings, their combination induced a significant reduction of cell viability in both cell lines. At the optimal experimental condition (i.e., 6 µg/mL of GNRs and 4.5 W/cm2 laser power density), GNR-assisted PTT reduced the cell viability of 4T1 and Pan02 cells by 94% and 87% and it was associated with maximum temperature changes of 25 °C and 29 °C (i.e., ∼1.8-fold increase compared to the laser-only condition), maximum absolute temperatures of 55 °C and 54 °C, and ETE values of 78% and 81%, for 4T1 and Pan02 cells, correspondingly. Also, the increase in the GNR concentration led to a decrease in the time constants, denoting faster heating kinetics upon irradiation. Furthermore, the thermal analysis parameters were correlated with the extent of cell death. Twelve hours after NIR exposure, GNR-assisted PTT was found to mainly trigger secondary apoptosis in both cell lines. The proposed study provides relevant insights into the relationship between temperature history and biological responses in the context of PTT. The findings contribute to the development of a universal methodology for evaluating thermal sensitivity upon NP-assisted PTT on different cell types and lay the groundwork for future translational studies.

Next Generation Risk Assessment approaches for advanced nanomaterials: Current status and future perspectives.

This manuscript discusses the challenges of applying New Approach Methodologies (NAMs) for safe by design and regulatory risk assessment of advanced nanomaterials (AdNMs). The authors propose a framework for Next Generation Risk Assessment of AdNMs involving NAMs that is aligned to the conventional risk assessment paradigm. This framework is exposure-driven, endpoint-specific, makes best use of pre-existing information, and can be implemented in tiers of increasing specificity and complexity of the adopted NAMs. The tiered structure of the approach, which effectively combines the use of existing data with targeted testing will allow safety to be assessed cost-effectively and as far as possible with even more limited use of vertebrates. The regulatory readiness of state-of-the-art emerging NAMs is assessed in terms of Transparency, Reliability, Accessibility, Applicability, Relevance and Completeness, and their appropriateness for AdNMs is discussed in relation to each step of the risk assessment paradigm along with providing perspectives for future developments in the respective scientific and regulatory areas.

Mucosa-penetrating liposomes for esophageal local drug delivery.

Local drug delivery to the esophagus is hampered by rapid transit time and poor permeability of the mucosa. If some strategies aimed to improve the residence time have been proposed, non-invasive approaches to increase the drug penetration in the mucosa have not been described so far. Herein, we designed mucosa-penetrating liposomes to favor the penetration and retention of curcumin (CURC) in the esophagus. A novel mucosa penetrating peptide (MPP), SLENKGP, was selected by Phage Display and conjugated to pegylated liposomes at different PEG and MPP's surface densities. Pegylation assured a long residence time of liposomes (at least 30 min) in the esophagus in vivo, but it did not favor the penetration of CURC in the mucosa. MPP-decorated liposomes instead delivered a significant higher amount of CURC in the mucosa compared to naked pegylated liposomes. Confocal microscopy studies showed that naked pegylated liposomes remain confined in the superficial layers of the mucosa whereas MPP-decorated liposomes penetrate the whole epithelium. In vitro, MPP reduced the interaction of PEG with mucin, meanwhile favoring the paracellular penetration of liposomes across epithelial cell multilayers. In conclusion, pegylated liposomes represent a valid approach to target the esophagus and the surface functionalization with MPP enhances their penetration in the mucosa.