Generation of HeLa spheroids in Ca-alginate-PEG microbeads using flicking technique as an improved three-dimensional cell culture system

In a conventional three-dimensional (3D) cell culture system based on microencapsulation, the calcium alginate microcapsules tend to rupture within 7 days of culture, causing unwanted cell leakage. The microencapsulation based on flicking model of calcium-alginate-polyethylene glycol (Ca-alg-PEG) was proposed to rectify this problem. An analytical model to simulate the flicking process based on the deflection of a needle cantilever was also successfully developed and used to predict the size of the microbeads. The size of the microbeads were ranged from 300 to 500 μm and it is controlled by varying the liquid flow rate from 4.8 to 366 μL/min and flicking speed from 70 to 120 rpm. Under a flicking force of 0.58 N, uniform sized and spherical shaped Ca-alginate-PEG microbeads were produced at a liquid flow rate of 40 μL/min and a flicking rate of 100 rpm. The microbeads were characterized by Field Emission Scanning Microscopy, Atomic Force Microscopy, Raman Spectroscopy and Nanoindentation, and the results indicated improved bio-physical properties of the ca-alginate microbeads after added with PEG. The cell viability test demonstrated that Ca-alginate-PEG microbeads were able to support the growth of viable HeLa cells into spheroids. Resilient calcium-alginate-polyethylene glycol (Ca-alg-PEG) microbeads were found to be able to last up to 15 days before rupturing and greatly reduced the cell leakage problem.