The first goal of this thesis was to investigate the potential of two cationic polysaccharides (PQ-4 and PQ-10) for DNA delivery. We have shown that, compared to PEI based polyplexes, they were less efficient in transfecting cells. However, as they had very low toxicity, further tailoring of the nature and extent of cationic side chains on cationic hydroxyethylcellulose may be a promising avenue to further enhance their DNA delivery properties. As a second goal we investigated the applications of digitally encoded microcarriers for cell based assays. We succeeded to show that encoded microcarriers were suitable to grow cells on. Neither the coating at the surface of the beads (which facilitates the growth of the cells), nor the cells themselves hampered the decoding of the beads, even when the cells covering the microcarriers exhibited green or red fluorescence due to the expression of GFP and RFP respectively. We were able (a) to immobilize DNA, siRNA or adenoviral particles on the surfaces of the encoded microcarriers by the use of polyelectrolytes and, subsequently, (b) to grow cells on top of the nucleic acids/adenoviral particles. The DNA and siRNA immobilized on the surface of the microcarrier were not able to transfect cells. However, we showed that the cells growing on the polyelectrolyte layer could indeed become transduced with adenoviral particles hosted by the polyelectrolyte layer. In conclusion, a proof of principal to use photophysically encoded microcarriers as transfected microarray has been shown. As a third goal we investigated the use of digitally encoded microcarriers as tool to combat counterfeiting of tablets. We showed that the codes in the Memobeads in tables produced by granulation did not deform during tabletting and that the code in the beads remained readable. We also found evidence that, after oral intake, the encoded microparticles are highly unlikely toxic to humans.