Nanocluster model of photothermal assay: application for high-sensitive monitoring of nicotine-induced changes in metabolism, apoptosis, and necrosis at a cellular level

Abstract

This study evaluates the capability of a photothermal (PT) assay to monitor the impact of nicotine on pancreatic cancer cells (AR42J). The specific PT response is closely proportional to nicotine concentrations at concentration range 1 nM to 100 microM, while at high concentrations of nicotine ranging from 1 mM to 50 mM, PT response shows dramatic decrease. According to the theoretical model, the mechanism of the PT assay is associated with metabolic and apoptotic-related shrinking of local cellular absorbing nanoscale zones caused by increased local absorption at low nicotine doses, while high doses of nicotine lead to apoptotic release of absorbing component (cytochrome c) into the intracellular space, and necrotic swelling of organelles, thereby causing a decrease in local absorption. This model is verified with conventional imaging and with Annexin-V Propidium iodide kits. The PT assay, in addition to its high sensitivity (3 orders of magnitude better than conventional assay), shows the potential to distinguish between various functional states of cells that are associated with changes in metabolism, early and late stages of apoptosis, and necrosis. Comparison of PT responses of pancreatic tumor cells AR42J with isolated primary pancreatic acinar cells and HepG2 cells shows a universal nature of PT assay.

In vivo photothermal flow cytometry: Imaging and detection of individual cells in blood and lymph flow

“…4 right: The biological basis for using PT assays to monitor cell responses to different environmental and therapeutic impacts can briefly be described as follows. Laser radiation initially interacts with endogenous cluster-forming nanoscale absorbers (i.e., absorbing cellular biomolecules, such as Cyt c, P450, and others) [Zharov et al, 2005c]. Because of the proximity of nanoabsorbers in these clusters, laserinduced optical, thermal, acoustic, and microbubble-formation phenomena around individual nanoabsorbers may overlap to create linear and nonlinear effects.…”

“…For example, shrinkage of absorbing clusters (e.g., whole cells or their organelles) is usually related to apoptosis, whereas swelling phenomena usually develop in the presence of lethal drug doses or necrosis. Spatial relocation of Cyt c may be related to its release by mitochondria during apoptosis [Tamaki et al, 2002;Zharov et al, 2005c].…”

“…In particular, in addition to being able to detect with high sensitivity (three orders of magnitude better than conventional assays) the impact of low doses of nicotine that are typically present in the blood of smokers, PTI also has the potential to distinguish between the various functional states of normal and cancer cells associated with nicotine-induced apoptotic and necrotic phenomena [Zharov et al, 2005c].…”

“…Simultaneously, the main parameters of microvessel function can be measured. These parameters include microvessel diameter, parameters of microlymphatic phasic contractions and valve activity, frequency of lymph flow oscillation, and width of the plasma layer near blood or lymph microvessel walls [Zharov et al, 2005c].…”

Fast Screening Techniques for Neurotoxigenic Substances and Other Toxicants and Pollutants Based on Thermal Lensing and Microfluidic Chips

“…8,20 However, high specificity can also be introduced into TLS measurements by applying a specific colorimetric reaction, [30][31][32][33] or the concept of bioanalytical assays. [34][35][36] The latter rely on the biorecognition capability of various biomolecules, such as enzymes and antibodies, which react or bind with the analyte with high specificity. Coupling TLS or TLM to bioanalytical techniques offers important improvements in the sensitivity as well as the selectivity of the determination of various analytes.…”