Investigation of Biophysical Mechanisms in Gold Nanoparticle Mediated Laser Manipulation of Cells Using a Multimodal Holographic and Fluorescence Imaging Setup

Abstract

Laser based cell manipulation has proven to be a versatile tool in biomedical applications. In this context, combining weakly focused laser pulses and nanostructures, e.g. gold nanoparticles, promises to be useful for high throughput cell manipulation, such as transfection and photothermal therapy. Interactions between laser pulses and gold nanoparticles are well understood. However, it is still necessary to study cell behavior in gold nanoparticle mediated laser manipulation. While parameters like cell viability or perforation efficiency are commonly addressed, the influence of the manipulation process on other essential cell parameters is not sufficiently investigated yet. Thus, we set out to study four relevant cell properties: cell volume and area, ion exchange and cytoskeleton structure after gold nanoparticle based laser manipulation. For this, we designed a multimodal imaging and manipulation setup. 200 nm gold nanoparticles were attached unspecifically to canine cells and irradiated by weakly focused 850 ps laser pulses. Volume and area change in the first minute post laser manipulation was monitored using digital holography. Calcium imaging and cells expressing a marker for filamentous actin (F-actin) served to analyze the ion exchange and the cytoskeleton, respectively. High radiant exposures led to cells exhibiting a tendency to shrink in volume and area, possibly due to outflow of cytoplasm. An intracellular raise in calcium was observed and accompanied by an intercellular calcium wave. This multimodal approach enabled for the first time a comprehensive analysis of the cell behavior in gold nanoparticle mediated cell manipulation. Additionally, this work can pave the way for a better understanding and the evaluation of new applications in the context of cell transfection or photothermal therapy.

Analysis of poration-induced changes in cells from laser-activated plasmonic substrates

“…The sample was exposed for fixed times using a mechanical shutter, and laser power was adjusted using an attenuation unit. A more detailed description of the setup can be found in [35].…”

“…To better understand and optimize the delivery process, it is important to analyze the induced membrane pores and associated cellular changes. Developing a biophysical understanding of the poration process by quantifying morphological cellular changes and studying how organelles behave after poration enables us to verify the safety of this technique for future applications [35,36].…”

Characterization of the cellular response triggered by gold nanoparticle–mediated laser manipulation

“…26 Recently, we were able to provide a comprehensive analysis of four important cell parameters: cell volume and area, ion exchange (calcium), and the cytoskeleton (filamentous actin) in resonant gold nanoparticle-mediated laser manipulation with 850 ps laser pulses by a multimodal imaging setup. 27 Despite these analyses, an exhaustive characterization of the transfection procedure requires an extension of this work to the perforation kinetics and oxidative or heat-induced cell stress phenomena. A detailed examination of these additional parameters was performed within this study and extends the biophysical and biochemical analysis of the cell response in laser transfection.…”

Biodegradable microsphere-mediated cell perforation in microfluidic channel using femtosecond laser

“…The scheme for GNOME laser transfection shows applications for cell manipulation reported in the latest publications. 17,18 The microfluidic platform is one of the attractive systems for obtaining synergy with laser-based technology for cell manipulation, including optoinjection. Microfluidic chips have been used for dispensing, 19 cell analyzing, 20 and cell sorting 21 as well as drug delivery.…”