Serum stability of 5′ cholesterol triethylene glycol-26-OKA and 39′ cholesterol triethylene glycol-24-OKA modified protoporphyrin IX DNA-aptamer and their in vitro heme binding characteristics

Square wave voltammetry based electrochemical determination of affinity of cholesterol triethylene glycol modified DNA-aptamers for protoporphyrin IX

“…It can be extracted from this experiment that conjugation of cholesterol triethylene glycol to OKA_24 ( = 27.62 ± 1.2 nM) and OKA_26 ( = 15.2 ± 1.68 nM) leads to decrease in binding affinity for heme by 3-fold in both COL-TEG_26-OKA ( = 4 7.13 ± 3.767 nM) and COL-TEG_24-OKA ( = 84.6 ± 8.7 nM) conjugate. Despite the fact that these findings disagreed with the prior findings obtained by carrying out an ultraviolet visible spectrum titrations of native and lipid conjugated aptamers with heme, [5] , it is not surprising because of the role played by the environmental influence on the conformation of molecules which can either enhance or reduce their activity [20] , [21] . Immobilization of heme on a glutaraldehyde-cysteamine coated gold electrode, for example, improved the binding affinity of both modified and unmodified aptamers for heme relative to their respective binding affinity in buffer solutions analyzed by UV spectral titration [5] (data not shown).…”

“…Despite the fact that these findings disagreed with the prior findings obtained by carrying out an ultraviolet visible spectrum titrations of native and lipid conjugated aptamers with heme, [5] , it is not surprising because of the role played by the environmental influence on the conformation of molecules which can either enhance or reduce their activity [20] , [21] . Immobilization of heme on a glutaraldehyde-cysteamine coated gold electrode, for example, improved the binding affinity of both modified and unmodified aptamers for heme relative to their respective binding affinity in buffer solutions analyzed by UV spectral titration [5] (data not shown). However, this increase in binding favors unmodified aptamers with 3-fold increase compared to lipid conjugated once.…”

“…This finding is in agreement with the report of Niles [10] on the influence of caping of these aptamers with inverted deoxythymidine. Similarly, spectral titration of heme with modified OKA_24 and OKA_26 aptamers has shown that such modification has not affect their specificity for heme [5] . Although the electrochemical properties dissipated by aptamer-conjugate have demonstrated that, lipid moiety conjugation to OKA_24 and OKA_26 aptamers, does not inhibit their heme binding properties, the need to get a quantitative measurement of the extent to which they have an affinity for heme was necessary.…”

“…Aptamers are small length nucleotide sequence of single strand RNA or DNA with desirable biological activities such as specific molecular target recognition. They are also antigenic-free biologics that can be selected to form a complex with molecular target of interest due to their ability to assume three-dimensional conformation [4] , [5] , [6] . Numerous aptamer target molecules have been reported.…”

Aptamer-engineered (nano)materials for theranostic applications

“…Scientific considerations include factors like charge, size, binding affinity, and ligand stability. In the case of antibodies, it is also crucial to consider their potential to trigger antibody-dependent cell-mediated cytotoxicity 32 , 33 . Aptamers have further been incorporated into the development of nanomaterials for drug delivery purposes within biological environments 34 - 37 .…”