Investigating a Lock-In Thermal Imaging Setup for the Detection and Characterization of Magnetic Nanoparticles

Abstract

Magnetic hyperthermia treatments utilize the heat generated by magnetic nanoparticles stimulated by an alternating magnetic field. Therefore, analytical methods are required to precisely characterize the dissipated thermal energy and to evaluate potential amplifying or diminishing factors in order to ensure optimal treatment conditions. Here, we present a lock-in thermal imaging setup specifically designed to thermally measure magnetic nanoparticles and we investigate theoretically how the various experimental parameters may influence the measurement. We compare two detection methods and highlight how an affordable microbolometer can achieve identical sensitivity with respect to a thermal camera-based system by adapting the measurement time. Furthermore, a numerical model is used to demonstrate the optimal stimulation frequency, the degree of nanomaterial heating power, preferential sample holder dimensions and the extent of heat losses to the environment. Using this model, we also revisit some technical assumptions and experimental results that previous studies have stated and suggest an optimal experimental configuration.

BODIPY-Based Photothermal Agents with Excellent Phototoxic Indices for Cancer Treatment

“…Aggregates formed by 1b in the cell could give rise to a photothermal MOA of 1b upon irradiation that triggers a cell death pathway through the local light-to-heat generation, similar to nanomaterials applied in PTT. 25 To test this hypothesis, the specific absorption rates (SARs), which are used in literature to experimentally quantify the heating efficiency of compounds, 66 of 1a and 1b were determined (Figure S27) using a lock-in thermal imaging setup (LIT) measuring the corresponding amplitude (section S36). Compound 1b shows overall higher SAR values compared to 1a (Table 4, Figure 4), which is in line with the behavior of the compounds regarding photocytotoxicity (Table 2).…”

BODIPY-Based Photothermal Agents for Cancer Treatment

“…Aggregates formed by 1b in the cell upon irradiation could give rise to a photothermal MOA of 1b upon irradiation involving a that triggers cell death pathway through the local light-to-heat generation, by the compound clusters similar to nanomaterials applied in PTT. [25] To test this hypothesis, the specific absorption rates (SARs), which are used in literature to experimentally quantify the heating efficiency of compounds [63] , of 1a and 1b were determined using a lock-in thermal imaging setup (LIT) measuring the corresponding amplitude (Fig. S19) as described in S35.…”

BODIPY-Based Photothermal Agents with Unprecedented Phototoxic Indices for Cancer Treatment

“…Aggregates formed by 1b in the cell upon irradiation could give rise to a photothermal MOA of 1b upon irradiation involving a that triggers cell death pathway through the local light-to-heat generation, by the compound clusters similar to nanomaterials applied in PTT. 25 To test this hypothesis, the specific absorption rates (SARs), which are used in literature to experimentally quantify the heating efficiency of compounds 66 , of 1a and 1b were determined (Fig. S27) using a lock-in thermal imaging setup (LIT) measuring the corresponding amplitude (S36).…”