Cell-specific multifunctional processing of heterogeneous cell systems in a single laser pulse treatment

Abstract

Current methods of cell processing for gene and cell therapies use several separate procedures for gene transfer and cell separation or elimination, because no current technology can offer simultaneous multifunctional processing of specific cell subsets in highly heterogeneous cell systems. Using the cell-specific generation of plasmonic nanobubbles of different sizes around cell-targeted gold nanoshells and nanospheres, we achieved simultaneous multifunctional cell-specific processing in a rapid single 70 ps laser pulse bulk treatment of heterogeneous cell suspension. This method supported the detection of cells, delivery of external molecular cargo to one type of cells and the concomitant destruction of another type of cells without damaging other cells in suspension, and real-time guidance of the above two cellular effects.

Figure 1

Multi-functional cell-specific processing of heterogeneous cell system with plasmonic nanobubbles (PNBs) that are selectively generated around the clusters of gold spheres in spheres-targeted cells (blue) and around the clusters of gold shells in shells-targeted cells (red) with a single laser pulse, resulting in the simultaneous delivery of molecular cargo into blue cells due to injection of the molecules (green dots) with small PNB and mechanical destruction of red cell with large PNB without the damage to other cells, all realized in a single pulse treatment.

Figure 2

PNBs in cells targeted with gold spheres (NSP) and shells (NS). (A): Bright field image of a mixture of J32 cells treated by NS-OKT3 (red arrow) and NSP-OKT3 (blue arrow); (B): optical scattering time-resolved image of large (bright) PNBs in NS-OKT3-treated cells (red) and small (dim) PNBs in NSP-OKT3-treated cells (blue); (C): PNB lifetime in NS-OKT3, NSP-OKT3, NS, NSPs -treated and intact cells, all obtained under exposure to a single laser pulse of 60 mJ/cm²; (D): PNB lifetime as a function of the laser pulse fluence for NS-OKT3 (solid red), NSP-OKT3 (solid blue), NS (hollow red), NSP (hollow blue) -treated and intact (solid black) cells.

Figure 3

(A): J32 cells with intracellular clusters of gold spheres (NSP-OKT3, blue DAPI marker) and shells (NS-OKT3, Calcein Red marker); (B): optical scattering PNB-specific time-responses of individual cells to a single laser pulse show simultaneous generation of small PNBs in blue and large PNBs in red cells in presence of extracellular molecular cargo FITC- Dextran (the lifetimes of PNBs are shown); (C): post-laser treatment blue cells show the injected FITC-Dextran (green fluorescence) and red cells show leaked out Calcein Red dye and distorted membranes due to their destruction. The fluorescence intensity profiles of individual cells in (A) and (C) are indicated by small color-matched arrows.

Figure 4

Parameters of individual red and blue cells targeted with NS-OKT3 and NSP-OKT3, respectively, after a single laser pulse treatment with PNBs (normalized by the corresponding parameters before the laser pulse): PNB lifetime (grey), cell destruction (shown through the viability level, magenta bars) and cargo delivery (shown through the level of green fluorescence, green bars); two types of gold NP-targeted cells are identified through the fluorescence of their markers, blue and red.

Figure 5

Experimental set up for the excitation and detection of plasmonic nanobubbles with two simultaneous techniques. (A) Generation of a vapor nanobubble around a gold NP cluster inside the cell. (B) Optical scattering response is obtained with a continuous probe laser (633 nm) that is focused into a sample collinearly with the excitation pulse. The scattering effect of the nanobubble reduces the axial intensity of the probe beam, which is measured by a fast photodetector. (C) Time-resolved optical scattering imaging employs side illumination with a probe laser pulse (70 ps, 580 nm, 2 nJ) that is delayed for 10 ns relative to the excitation pulse. The probe light is scattered by the water-vapor boundary of the nanobubble and generates a distinct image in the microscope.