Real-time assessment of cigarette smoke particle deposition in vitro

Abstract

BackgroundRecently there has been a rapid increase in approaches to assess the effects of cigarette smoke in vitro. Despite a range of gravimetric and chemical methods, there is a requirement to identify simpler and more reliable methods to quantify in vitro whole smoke dose, to support extrapolation and comparisons to human/in vivo dose. We have previously characterised an in vitro exposure system using a Borgwaldt RM20S smoking machine and a chamber exposing cellular cultures to whole smoke at the air-liquid interface. In this study we demonstrate the utility of a quartz crystal microbalance (QCM), using this exposure system, to assess real-time cigarette smoke particulate deposition during a 30 minute smoke exposure. Smoke was generated at various dilutions (1:5–1:400, smoke:air) using two cigarette products, 3R4F Kentucky reference and 1 mg commercially available cigarettes. The QCM, integrated into the chamber, assessed particulate deposition and data generated were compared to traditional chemical spectrofluorometric analysis.ResultsThe QCM chamber was able to detect mass differences between the different products within the nanogram range. 3R4F reference cigarette smoke deposition ranged from 25.75 ±2.30 μg/cm2 (1:5) to 0.22 ±0.03 μg/cm2 (1:400). 1 mg cigarette smoke deposition was less and ranged from 1.42 ±0.26 μg/cm2 (1:5), to 0.13 ±0.02 μg/cm2 (1:100). Spectrofluorometric analysis demonstrated statistically significant correlation of particulate deposition with the QCM (p < 0.05), and regression R2 value were 97.4 %. The fitted equation for the linear model which describes the relationship is: QCM = −0.6796 + 0.9744 chemical spectrofluorescence.ConclusionsWe suggest the QCM is a reliable, effective and simple tool that can be used to quantify smoke particulate deposition in real-time, in vitro and can be used to quantify other aerosols delivered to our chamber for assessment.

Cigarette Mainstream Smoke: The Evolution of Methods and Devices for Generation, Exposure and Collection

“…A study similar to the one just discussed (13) for "an exposure device", which obviously followed the principles underlying the exposure chamber described by MASSEY et al (13) though with a quite differently designed top portion featuring a horizontal discshaped metal plate for homogeneous smoke dispersion and three holes in the base for housing inserts. This chamber (Figure 49) -called "BAT exposure chamber" in several publications -was used in a number of BAT research projects (472)(473)(474)(475)(476)(477), discussed below, in combination with the Borgwaldt smoking machine RM20S. The Borgwaldt RM20S is a cigarette smoking machine (first commercialized in 2002) for the generation, dilution and transfer of mainstream smoke for direct in vitro exposure of cells and tissues (108).…”

“…Dependable dosimetric data are essential for the interpretation of in vitro toxicity findings and their extrapolation to human exposure scenarios. Linking up the RM20S smoking machine (108) and BAT exposure chamber (471), ADAMSON et al (475) examined the applicability and reliability of a quartz crystal microbalance (QCM) system for the real-time assessment of cigarette smoke particle deposition. Changes in oscillation frequency of a quartz crystal, held between two electrodes, were recorded under the influence of increased particle deposition -a gravimetric approach first explored and developed in 1959 by SAUERBREY (481).…”

“…However, the use of dilution air flow rates -a simple and easily controllable parameter -in addi- Brought to you by | MIT Libraries Authenticated Download Date | 5/11/18 10:15 PM tional ambitious calculations looks like a daring exercise as long as their relationship with exposure intensity and particle deposition (measured by QCMs with whole smoke) is yet insufficiently understood. Following up on their earlier studies (475,476), in which the RM20S smoking machine (108) was combined with the BAT exposure chamber (471), ADAMSON et al (492) documented the deposition of smoke particles in real time by means of a quartz crystal microbalance (QCM) system (technical details explained above), now integrating the VC 10 ® smoking robot (450) and the dilution system with the Vitrocell ® mammalian 6/4 stainless exposure module. 3R4F Kentucky reference cigarettes were smoked under ISO conditions in single mode (one cigarette only smoked at a time, and three cigarettes smoked consecutively with eight puffs each for a total exposure time of 24 min).…”

“…This way, different smoke generation and dilution systems can be characterized and compared directly regarding their performance and potential to supply suitable atmospheres for exposure studies. After three earlier studies (475,476,492) had convincingly demonstrated the value of quartz crystal microbalances (QCMs) for the quantitative assessment of cigarette smoke particle deposition, ADAMSON et al (493) used QCM technology for a comparative evaluation of Vitrocell ® smoke generation and exposure systems. The direct gravimetric measurement of precipitated mass per surface area in real time and in situ offered considerable advantages over traditional methods, such as measurement of fluorescence or differential mobility spectrometry backed by specific air flow rates.…”

“…When different concentrations of smoke were examined a linear correlation between optical density and dilution was shown. In the very same experiment, quartz crystal microbalances (QCMs) were installed into each of the seven pipe connectors between the smoke dilution elements and the base module -and not placed in any of the wells as done by ADAMSON et al (475,476,492,493) in a number of earlier studies. Particle deposition was monitored online and the final mass determined at the end of the smoking run.…”