An approach to an established technique that is potentially applicable for a more comprehensive understanding of the electrical properties of red blood cells (RBCs) is presented. Using a high-intensity gradient laser trap, RBCs can be singly trapped and consequentially ionized. The subsequent dynamics of the ionized cell allows one to calculate the charge developed and the ionization energy (IE) through a Newtonian-based analysis. RBCs with two different hemoglobin (Hb) types were ionized. The first sample was identified as carrying Hb HbAA (normal Hb) and the second one was identified as carrying HbAC (HbC trait). By analyzing the charge developed on each cell and several other related factors, we were able to discern a difference between the main Hb types contained within the individual RBC, independent of cell size. A relationship between the charge developed and the IE of the cell was also established based on the electrical properties of RBCs. Thus, we present this laser trapping technique as a study of the electrical properties of RBCs and as possible biomedical tool to be used for the differentiation of Hb types.

We used laser trapping to study the effects of suffruticosol B on lung cancer cells. Physical and mechanical changes were found to be statistically significant, with a 63.97% increase over untreated cells and a 79.57% increase over untreated cells after treatment for 3 or 6 h, respectively. The treatment affected the internal structure of the cells, with changes in their elastic properties. The cellular responses showed that treatment with suffruticosol B resulted in the decreased proliferation and invasion of cancer cells. These results suggest that the treatment may be useful in preventing or treating lung cancer.

. Significance: We introduce a model for better calibration of the trapping force using an equal but oppositely directed drag force acting on a trapped red blood cell (RBC). We demonstrate this approach by studying RBCs’ elastic properties from deidentified sickle cell anemia (SCA) and sickle cell trait (SCT) blood samples. Aim: A laser trapping (LT) force was formulated and analytically calculated in a cylindrical model. Using this trapping force relative percent difference, the maximum (longitudinal) and minimum (transverse) radius rate and stiffness were used to study the elasticity. Approach: The elastic property of SCA and SCT RBCs was analyzed using LT technique with computer controlled piezo-driven stage, in order to trap and stretch the RBCs. Results: For all parameters, the results show that the SCT RBC samples have higher elastic property than the SCA RBCs. The higher rigidity in the SCA cell may be due to the lipid composition of the membrane, which was affected by the cholesterol concentration. Conclusions: By developing a theoretical model for different trapping forces, we have also studied the elasticity of RBCs in SCT (with hemoglobin type HbAS) and in SCA (with hemoglobin type HbSS). The results for the quantities describing the elasticity of the cells consistently showed that the RBCs in the SCT display lower rigidity and higher deformability than the RBCs with SCA.

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Application of high intensity gradient laser trap for charging a single cell is demonstrated. We used RBCs from normal person (AA hemoglobin) and an individual with sickle cell trait (AC hemoglobin). OCIS codes: (170.0170) Medical optics and biotechnology; (350.4855) Optical tweezers or optical manipulation IntroductionHigh performance liquid chromatography HPLC [1] is commonly used to determine the hemoglobin types present in a blood sample. Hemoglobin (Hb) quantitation in a blood sample is essential in screening sickle cell disease (SCD) and also in monitoring patients receiving various types of treatments. HPLC techniques employ principles of ion exchange chromatography and spectrophotometric detection. In this technique a few microliters of blood is hemolyzed and injected onto a positively charged column of HPLC. At a moderately alkaline pH, all hemoglobin cells carry a variable net negative charge and bind with the positive charge. However, the magnitude of the negative charge varies from one type of hemoglobin to another. Although there are many types of hemoglobin, the most common hemoglobin types found in blood are HbF, HbA, HbS, and HbC. In this order HbF has the weakest and HbC has the strongest negative charge. When these differentially negatively charged hemoglobin types are injected into the positively charged HPLC column, the HbF type will bind weakly and be eluted quickly from the column whereas the HbC type will bind more strongly and be retained longer on the column. Here we present a new technique that can be used to identify the different types of hemoglobin and the magnitude of the charge on the molecules. This technique is based on high intensity laser trapping of a single RBC. Laser trapping (LT) [2] techniques have been widely used to study the mechanical properties of RBCs [3,4]. In this study, we report our new procedure that demonstrates how individual RBCs can be charged, and the magnitude of the charge can be measured. We used a blood sample from an individual with sickle cell trait (SCT) and the AC hemoglobin type and a healthy subject with the AA hemoglobin type. Experimental MethodThe design and detailed discussion of the LT we used can be referenced in our recently reported studies on LT biomedical application [3]. Here we only discuss the basic elements of the experimental set-up that are needed to explain the procedure. The basic elements of the LT we used for this study are the laser, the microscope equipped with a high numerical aperture; a computer controlled digital camera, and a piezo-driven mechanical stage. The laser we used to form the trap is a linearly polarized infrared diode laser (5 watts at 1064nm) for which the power was controlled by a λ/2-wave plate and polarizer combination. After the laser beam was expanded and aligned, it was coupled to an inverted microscope (Olympus IX 71) and redirected for a normal incidence angle at the center of the back of an objective lens (OL) of the microscope using a dichroic mirror (DM) positioned at 45° inside the microscope to fo...