Biocompatibility effect

Data on the biocompatibility of gelatin microspheres is extremely limited. Drug-free microspheres elicited no untoward effects when injected intravenously into mice over a 12-week period (159). When albumin microspheres were injected repeatedly into the knee joints of rabbits, pronounced rapid joint swelling occurred after the second and subsequent injections. By comparison, no swelling occurred when gelatin microspheres were administered (160). 

This preservative has been used in a dry eye treatment and was shown in a clinical study to have the same biocompatibility as another marketed preparation [152]. Cetrimonium chloride (0.01%) produced the same corneal and conjunctival changes after one-month ocular administration in rats as the effective levels of other major preservatives [153],... 

The effect of the material on cellular metabolism is also an important measure of biocompatibility. To determine such effects, cultured ex vivo cells can be exposed to the polymer and the growth rates compared to controls [216,217], The metabolic function of the cells can be tested by assay for production of a marker enzyme. An additional advantage of this type of test is that it avoids the use of live animals. 

The realization of the reasons for poor biocompatibility of general alkoxides with biopolymers led to the development of approaches to minimize or eliminate the problem of the detrimental effect of alcohols. This can be done in two ways modification of the sol-gel processing or the silica precursor. This is considered in some detail below. 

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