Cancer cell uptake behavior of Au nanoring and its localized surface plasmon resonance induced cell inactivation

Abstract

Au nanorings (NRIs), which have the localized surface plasmon resonance (LSPR) wavelength around 1058 nm, either with or without linked antibodies, are applied to SAS oral cancer cells for cell inactivation through the LSPR-induced photothermal effect when they are illuminated by a laser of 1065 nm in wavelength. Different incubation times of cells with Au NRIs are considered for observing the variations of cell uptake efficiency of Au NRI and the threshold laser intensity for cell inactivation. In each case of incubation time, the cell sample is washed for evaluating the total Au NRI number per cell adsorbed and internalized by the cells based on inductively coupled plasma mass spectrometry measurement. Also, the Au NRIs remaining on cell membrane are etched with KI/I2 solution to evaluate the internalized Au NRI number per cell. The threshold laser intensities for cell inactivation before washout, after washout, and after KI/I2 etching are calibrated from the circular area sizes of inactivated cells around the illuminated laser spot center with various laser power levels. By using Au NRIs with antibodies, the internalized Au NRI number per cell increases monotonically with incubation time up to 24 h. However, the number of Au NRI remaining on cell membrane reaches a maximum at 12 h in incubation time. The cell uptake behavior of an Au NRI without antibodies is similar to that with antibodies except that the uptake NRI number is significantly smaller and the incubation time for the maximum NRI number remaining on cell membrane is delayed to 20 h. By comparing the threshold laser intensities before and after KI/I2 etching, it is found that the Au NRIs remaining on cell membrane cause more effective cancer cell inactivation, when compared with the internalized Au NRIs.

Gold Nanoparticle Mediated Phototherapy for Cancer

“…Like gold nanorings with the LSPR wavelength range between 1000 and 1300 nm [60], gold nanostars possess more SPR hot spots [59], hollow gold nanoshells [62], and gold-gold sulfide nanoparticles [102]. Chu et al utilized gold nanorings functionalized with anti-EGFR antibody for successful targeting and inactivation of SAS oral cancer cells under irradiation of a 1065 nm laser [103]. Yang et al and Zhang et al have conducted NIR photothermal therapy mediated by citrate-capped gold nanoflowers and gamma Fe 2 O 3 @Au core/shell-type magnetic gold nanoflower, respectively [44,104].…”

Important factors for cell-membrane permeabilization by gold nanoparticles activated by nanosecond-laser irradiation

“…Moreover, internalized AuNPs are less effective in cell inactivation compared with AuNPs remaining on the cell membrane. 32 We can speculate that AuNPs inside cells are less efficient in permeabilization of the membrane, but destroy internal cellular structures for localized thermal damage. 33 The evolving cavitation bubbles around the particles can have diameters up to the micrometer range, and could damage intracellular structures and compartments, like endo/lysosomes, mitochondria, or the endoplasmic reticulum.…”

Enhancements of Cancer Cell Damage Efficiencies in Photothermal and Photodynamic Processes through Cell Perforation and Preheating with Surface Plasmon Resonance of Gold Nanoring

“…Au NRIs were fabricated first on a polymer substrate based on the techniques of nano-imprint lithography and ion-bombardment induced Au sputtering in a reactive ion etching process [22,23,24]. Briefly speaking, regularly patterned nanopillars were formed first on a polymer substrate through the processes of nano-imprint and dry etching.…”

“…In this spectral range, light can penetrate into tissue the deepest [22,23,24,25]. When Au NRIs taken up by cells are excited by a light source with the wavelength close to its LSP resonance peak, the enhanced absorption can produce a strong PT effect for causing cancer cell damage [22,23,24,25]. By linking a photosensitizer to Au NRIs for cell uptake, i.e., using Au NRIs as the photosensitizer carrier, an illumination to excite the photosensitizer can result in the PD effect.…”