Table 2.

Essential considerations in selecting a suitable polymer for protein-polymer conjugation [143].

Factors Must Be Consider	Example	Description
Identity	PEG and PEG analogs	Increases the hydrodynamic radius, decreasing immunogenicity
	Stimuli-responsive polymers	Thermo responsive: p(NIPAAm) pH-responsive: poly(acrylic acid) and p(DMAEMA)
	Biomimetic polymers	Trehalose Heparin-mimicking polymers: poly(styrene sulfonate) and poly(vinyl sulfonate)
	Degradable polymers	Cyclic ketene acetals copolymerized with vinyl monomers: degradable under basic pH Hydroxyethyl starch: a-amylase sensitive
Toxicity	Hydroxyethyl starch	Plasma volume expander
Molecular weight	PEGylated proteins	Decreasing renal filtration
Polymer architecture	Branched, brush and linear polymers are accessible to be conjugate with proteins.	Stimulating the immune system
Polymer solubility	-	Soluble in the range between 100 and 500 mg/mL

Abbreviations: PEG: poly ethylene glycol; p(NIPAAm): poly(Nisopropylacrylamide); p(DMAEMA): poly((N,N-dimethylamino)ethyl methacrylate).