In this work, we report a fast and accessible method for quantification of cetyltrimethylammonium bromide (CTAB) in solutions of gold nanorods (GNRs) by bromophenol blue (BPB) ion-paring formation and spectrophotometric detection. The ion-par method used to quantify CTAB exhibited adequate figures of merit and was applied to the quantification of CTAB present in solutions of GNRs-CTAB and in GNRs-CLPFFD samples obtained by the seed growth method. This type of methodology could be extensive to others surfactants employed for the synthesis of nanoparticles. In addition, this method allows screening CTAB in GNRs samples and consequently would help to know if CTAB concentration is lower than an acceptable cut-off for cell viability analysis.

The malarial GBP 130 protein binds weakly to intact human erythrocytes; the binding sites seem to be located in the repeat region and this region's antibodies block the merozoite invasion. A peptide from this region (residues from 701 to 720) which binds to human erythrocytes was identified. This peptide named 2220 did not bind to sialic acid; the binding site on human erythrocyte was affected by treatment with trypsin but not by chymotrypsin. The peptide was able to inhibit Plasmodium falciparum merozoite invasion of erythrocytes. The residues F701, K703, L705, T706, E713 (FYKILTNTDPNDEVERDNAD) were found to be critical for peptide binding to erythrocytes.