Preparation of Smart pH-Responsive Cell Laden Hybrid Hydrogel Microsphere Using Carbon Dots

Background and Aim: Cell culture in 3D microenvironments mimickingphysiological conditions. One of the suitable models for solid tumor ismicrosphere due to the formation of the poor perfusion condition whichcauses similar hypoxic and acidic region in tumor mass. Accordingly,measuring the amount of acidity inside these types of cancer modelscan help to understand the status of the cells. To achieve this goal, weproposed a facile method for recording the interior pH of cell-ladenhydrogel microsphere without sectioning and staining.Methods: In the first step, the carbon dots (CDs) were synthesized using ahydrothermal method. The prepared CDs were characterized by dynamiclight scattering and fluorescent spectrofluorimetric techniques. Thenthe CDs solution was lyophilized and CDs dry powder was added tothe mixture of alginate hydrogel and cell culture medium with a cellconcentration of 103 cells/mL. In the next step, the CDs-hydrogel particleswere prepared trough automatic pipetting the prepared mixture to theCaCl2 solution. The size of hydrogels was adjusted by pumping flowrate. After bead formation, the hydrogel particles removed and washedwith PBS buffer. The prepared cell-laden hydrogels were transferred tothe 6-well plate contacting culture medium and incubated at 37 o C. Thefluorescent intensity of incubated hydrogels was measured through labmade smart-phone spectrofluorometer over a period of 5 days.Results: Excitation and emission wavelengths of prepared CDs wereindependent which is suitable for pH measurement. The MTT assayshowed low toxicity effect of CDs on MCF7. The shape and thediameter size (500 ± 45 μM) of prepared hydrogels were uniforms. Thefluorescence intensity of the cell-laden hydrogel particles increased overtime and peaked on the 5th day. This fluorescence emission incrementindicates an increase in the acidity of the microsphere interior.Conclusion: The proposed method for preparing hybrid hydrogel cellladenmicrosphere provide appropriate tumor model for imaging andanticancer drug investigation.

کلیدواژه ها:

Cell-laden microsphere ، Hydrogel ، Carbon dots ، pHresponsive