Strategy DPolyecaprolactone and PolyDLlactide Microspheres with Adsorbed Human Serum Albumin and Gamma Globulin [43

Biodegradable polyester microspheres are considered to be good candidates for protein and oligopeptide transportation. Examples of human serum albumin

[Ethyl salicylate]^, g/1

[Ethyl salicylate]^, g/1

FIG. 29 Loading of ethyl salicylate into poly(e-caprolactone) microspheres by swelling. Concentration of ethyl salicylate in microspheres as a function the initial drug concentration. (From Ref. 65.)

(HSA) and human gamma globulin (yG) adsorption onto poly(e-caprolactone) and poly(d,l-lactide) microspheres are given below.

Suspensions of poly(e-caprolactone) microspheres (Dn = 0.63 pm, particle concentration 3.12 mg/mL) and/or poly(d,l-lactide) microspheres (2.50 pm, 16.6 mg/mL) in phosphate buffer (pH 7.4) were incubated with HSA and/or yG at varied protein concentrations. Incubation was carried out at room temperature for 12 h. Surface concentrations of attached proteins (rHSA and ryG) as a function of protein concentration in solution are shown in Figs. 30 and 31. According to these figures, the maximal surface concentrations of adsorbed proteins at plateaus corresponding to saturation of surfaces of microspheres with proteins are as follows: For poly(e-caprolactone) microspheres rHSA(max) = 1.0 mg/m2 and ryG(max) = 2.6 mg/m2, whereas for poly(d,l-lactide) microspheres rHSA(max) = 0.9 mg/m2 and ryG(max) = 1.7 mg/m2. It is worth noting that adsorption of HSA and yG onto polyester microspheres is only about 30% lower than for polystyrene microspheres used for many applications (e.g., in medical diagnostics) as convenient supports for protein adsorption [43].

[Protein], mg/nil

FIG. 30 Surface concentrations of proteins (rHSA and ryG) adsorbed onto poly(£-capro-lactone) microspheres as functions of protein concentrations in solution. (From Ref. 43.)

[Protein], mg/nil

FIG. 30 Surface concentrations of proteins (rHSA and ryG) adsorbed onto poly(£-capro-lactone) microspheres as functions of protein concentrations in solution. (From Ref. 43.)

FIG. 31 Surface concentrations of proteins (rHSA and ryG) adsorbed onto poly(d,l-lactide) microspheres as functions of protein concentrations in solution. (From Ref. 43.)

FIG. 31 Surface concentrations of proteins (rHSA and ryG) adsorbed onto poly(d,l-lactide) microspheres as functions of protein concentrations in solution. (From Ref. 43.)

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