No abstract

Laser-induced ionization process led to an ultrafast reversible destabilization of the phospholipid layer of the cellular membrane. The inner cell membrane remained intact during the attachment procedure, and isolation of the cells' cytoplasm from the surrounding medium was obtained. A strong physical attachment between the cells was obtained due to the bonding of the membranes' ionized phospholipid molecules and the formation of a joint cellular membrane at the connection point. The cellular attachment technique, femtosecond laser-induced cell-cell surgical attachment, can potentially provide a platform for the creation of engineered tissue and cell cultures.

This article provides insight into the mechanism of femtosecond laser nanosurgical attachment of cells. We have demonstrated that during the attachment of two retinoblastoma cells using sub-10 femtosecond laser pulses, with 800 nm central wavelength, the phospholipid molecules of both cells hemifuse and form one shared phospholipid bilayer, at the attachment location. In order to verify the hypothesis that hemifusion takes place, transmission electron microscope images of the cell membranes of retinoblastoma cells were taken. It is shown that at the attachment interface, the two cell membranes coalesce and form one single membrane shared by both cells. Thus, further evidence is provided to support the hypothesis that laser-induced ionization process led to an ultrafast reversible destabilization of the phospholipid layer of the cellular membrane, which resulted in crosslinking of the phospholipid molecules in each membrane. This process of hemifusion occurs throughout the entire penetration depth of the femtosecond laser pulse train. Thus, the attachment between the cells takes place across a large surface area, which affirms our findings of strong physical attachment between the cells. The femtosecond laser pulse hemifusion technique can potentially provide a platform for precise molecular manipulation of cellular membranes. Manipulation of the cellular membrane is an important procedure that could aid in studying diseases such as cancer; where the expression level of plasma proteins on the cell membrane is altered.

Retinoblastoma is a cancerous disease that affects the retina, and primarily affects young children. To date, the primary treatment goal of retinoblastoma is to save the child's life, while the preservation of the eye and its functionality are the secondary goals. Reoccurrence of tumors is mainly attributed to the persistence of cancer stem cells. EpCAM+ Y79 retinoblastoma cells behave like cancer stem cells and are recognized as cells that are resistant to treatment. We demonstrate an effective technique to treat retinoblastoma cancer cells, using femtosecond laser pulses and epithelial cell adhesion molecule (EpCAM)-targeting gold nanorods (Au-NRs). Complete assessment of the optimal laser parameters required for the development of a translational retinoblastoma cancer treatment is provided. Both an MTS cellular metabolism assay and a fluorescence viability assay demonstrate an astonishing cellular viability drop, to 10%. Right after laser irradiation the cellular membrane ruptures. Calculations and field-emission scanning electron microscopy (FESEM) imaging show that Au-NRs reach melting temperature after laser pulse exposure. Delivering femtosecond laser pulses directly onto the retina to treat retinoblastoma through the medium of the eye is possible without interacting with its compartments-making this treatment ideal for this type of cancer. This treatment methodology would be an invaluable

Neuronal injury may cause an irreversible damage to cellular, organ and organism function. While preventing neural injury is ideal, it is not always possible. There are multiple etiologies for neuronal injury including trauma, infection, inflammation, immune mediated disorders, toxins and hereditary conditions. We describe a novel laser application, utilizing femtosecond laser pulses, in order to connect neuronal axon to neuronal soma. We were able to maintain cellular viability, and demonstrate that this technique is universal as it is applicable to multiple cell types and media.