A choice of anticancer drugs have been conjugated with polymers, including anthracycline antibiotics, antimetabolites, platinum analogues, alkylating agents, as well as peptides, proteins and enzymes (Meng, and El-Deiry, 2002). The main requirement for a candidate drug in this field is the drug minimum effective concentration. For example, if the minimum effective concentration needs to be ~10 '3 M for a drug with a molecular weight of -50 kDa, it becomes impractical. In regard to the candidate conjugated polymers, both natural and synthetic materials are used, e.g. polysaccharides, gelatin, amino acids, polyethyleneglycol (PEG), and numerous polyacrylates (Rock, and DeMichele, 2003). These …show more content…
• The conjugated drugs must be stable in the lysosomal environment.
• Active drugs should be able to pass across the lysosomal membrane to reach pharmacological target.
• Active drugs should be released at a rate fitting their functional mechanism.
• Polymers must be water-soluble, biocompatible, non toxic or immunogenic, preferably biodegradable.
• Polymers should be able to carry the required load of the drug.
• Polymers should be able to protect the drugs against premature metabolism in delivery.
• Polymers should avoid rapid clearance, such as liver …show more content…
(2006) stated that Protein PEGylation generally includes two steps. An inert PEG polymer is first chemically activated by the appropriate functionalization in order to react with an enzyme. The choice of the suitable group for the activated PEG derivative is based on the type of available reactive group on the molecule, to which PEG will be conjugated. For proteins, typical reactive amino acids include lysine, cysteine, histidine, arginine, aspartic acid, glutamic acid, serine, threonine, tyrosine as well as N-terminal amino acid group and the C-terminal carboxylic acid. Among them, lysine and N-terminal amino acid groups are the most used for the protein PEGylation (Wilson et al.