Immunoreactivity changes of human serum albumin and alpha-1-microglobulin induced by their interaction with dendrimers.

Dendrimers are hyperbranched polymers for delivery of therapeutic genetic material to cancer cells. The fine tuning chemical modifications of dendrimers allow for the modification of the composition. The architecture and the properties of dendrimers are key factors to improve their in vitro and in vivo properties such as biocompatibility with cells and tissues and their pharmacokinetic/pharmacodynamic behavior. The side effects of dendrimers on structure and function of proteins is an important question that must be addressed. We herein describe the effect of newly synthesized piperidine-based cationic phosphorous dendrimers of 2 generations and commercial cationic, neutral and anionic poly(amidoamine) (PAMAM) dendrimers of 4th generation on immunochemical properties of 2 serum proteins: human serum albumin (HSA) and alpha-1-microglobulin (A1M). Both can bind and transfer ligands in blood, including hormones, fatty acids, toxins and drugs, and have immunoreactivity properties. Comparing the effects of piperidinium-terminated phosphorus and cationic, neutral and anionic PAMAM dendrimers on HSA and A1M, we conclude that, in the case of equimolar complexes, these dendrimers had no significant effect on immunoreactivity of proteins. In contrast, the formation of complexes in which a protein is fully bound to dendrimers leads to partial (1.2-2.3 times) reduction in protein immunoreactivity. The most important fact is that dendrimer-induced change in immunoreactivity of proteins is not complete, even if the protein is entirely bound by dendrimers. This means that the application of dendrimers in vivo will not totally hamper the immunoreactivity of these proteins and antibodies.

Dendronization of gold nanoparticles decreases their effect on human alpha-1-microglobulin.

Gold nanoparticles are new kinds of nanomaterials. Their large surface-to-volume ratio, stability, excellent biocompatibility, low toxicity and functionality make them very attractive for biomedical applications. Therefore we have analyzed how dendronized gold nanoparticles interact with human alpha-1-microglobulin. This is a glycoprotein of ∼30kDa present in blood plasma and some tissues of the human body. Comparing 3 nanoparticles with different dendronization, we conclude that the effect of a nanoparticle on the structure of alpha-1-microglobulin significantly decreased with second and third generations dendrons as a result of less exposure of the metal cores in the nanoparticles. These interactions indicate weak changes in the immunochemical properties of the protein, whereas the dendron coating had no effect. Thus, dendronization of gold nanoparticles helps to modify their binding properties by shielding them from interactions with plasma proteins.

Role of cationic carbosilane dendrons and metallic core of functionalized gold nanoparticles in their interaction with human serum albumin.

Functionalization of gold nanoparticles by different chemical groups is an important issue regarding the biomedical applications of such particles. Therefore we have analyzed the interaction between gold nanoparticles functionalized by carbosilane dendrons with human serum albumin at different pHs, and in the presence of the protein unfolding agent, guanidine hydrochloride, using circular dichroism, zeta-potential and fluorescence quenching. The effect of a nanoparticle dendronization and pure dendrons on the immunoreactivity of albumin was estimated using ELISA. In addition, the tool to estimate the binding capacity of dendronized gold nanoparticles using a hydrophobic fluorescent probe 1,8-ANS (1-anilinonaphthalene-8-sulfonic acid) was chosen. We concluded that the effect of a nanoparticle on the structure, immunochemical properties and unfolding of albumin significantly decreased with second and third generations dendrons attached. Differences in pH dependence of the interaction between nanoparticles, their dendrons and albumin showed several effects of the "dendritic corona" and the metallic part of nanoparticle on the protein. These interactions indicate changes in the immunoreactivity of the protein, whereas dendron coating per se had no effect. Thus, dendronization of gold nanoparticles helps to shield them from interactions with plasma proteins.