Hybrid Supports for Oligonucleotide Synthesis: Controlled Pore Glass Derivatives with Branched Amine‐Ended Polyether or Polyimine

Abstract

Controlled pore glass (CPG), differing in pore size and subsequent specific surface, was chemically modified by: (1) increasing surface susceptibility for amine functionalization via reaction with oxirane‐type (active) and alkyl/aryl‐type (inactive towards amine compounds) silane pro‐adhesive compounds, and (2) immobilization of trimethylolpropane tris[poly(propylene glycol), amine terminated] ether, comb‐like 8‐arm octa[poly(ethylene glycol) amine] with each branch amine terminated, and a poly(propylene imine) amine‐terminated second‐generation dendrimer. The increase in surface density of amine functions—monitored by UV‐Vis technique adopted for quantitative measurements of Ruhemann’s purple intensity—improved final loading capacity, characterized by dimethoxytrityl cation absorption. Obtained materials proved their applicability in automatic oligonucleotide (ON) synthesis, especially when silanized 2000 Å CPG modified with 8‐arm octa[poly(ethylene glycol) amine], with deduced empirical formula CPG—silane—(NH)5.7PEG‐(NH2)2.3, was used for long‐chain (150 nucleotides) ONs synthesis. This can be regarded as a good CPG support for this purpose. Moreover, hybrid supports with different porosity allowed the synthesis of shorter ONs with satisfactory yield and purity, monitored by RP‐HPLC and MALDI‐TOF. On the molecular level, two competitive mechanisms seem to influence the utility of the final hybrid support: spatial availability of active sites and the propensity of the functionalizer to bond with the CPG surface.