Cellulose microbeads were made by regenerating cellulose from cellulose triacetate (CTA) microbeads. In a typical process, 1 g of cellulose triacetate (Aldrich) was completely dissolved in 20ml of CH2 Cl2 . The CTA/CH2 Cl2 solution (5%) was then poured into a special glass vessel containing 4g of polyvinyl alcohol disper- sant in 200 mL of Milli-Q water. The system was then continuously stirred for 24 h at room temperature. CTA microbeads were then filtered, washed in deionised water and vacuum dried at 45 ◦ C for 3 days. Cellulose was regenerated from CTA microbeads by a saponification reaction [40]. In a typical process, 0.5g of CTA microbeads were suspended in 100 ml of Milli-Q water over night. The microbeads were then filtered and cellulose was regenerated by heating the CTA microbeads at 90◦C in a solution of 0.05N NaOH continuously stirred for 12h. The microbeads were then collected by filtration, washed thoroughly in Milli-Q water and vac- uum dried at 45 ◦ C for 3 days. The cellulose regeneration process was verified by IR spectroscopy (Perkin Elmer) on CTA microbeads (non-regenerated), regenerated microbeads, and pure cellulose
powder. A single microbead of cellulose was then glued (Loctite 3040) at the extreme end of an AFM cantilever tip. The glue was allowed to cure for 48 h under ambient conditions. The radius of the attached microbead measured by the SEM was estimated to be 9.15 ± 0.63