The present invention relates to delivery systems. In particular, the present invention provides microporous scaffolds having thereon agents (e.g., extracellular matrix proteins, exendin-4) and biological material (e.g., pancreatic islet cells). In some embodiments, the scaffolds are used for transplanting biological material into a subject. In some embodiments, the scaffolds are used in the treatment of diseases (e.g., type 1 diabetes), and related methods (e.g., diagnostic methods, research methods, drug screening).