Electrostatic interaction effect for human DNA separation with functionalized mesoporous silicas Hong Kyung Choi a,b , Jeong Ho Chang a,n , Il Hwan Ko a , Jin Hyung Lee a , Bong Yong Jeong a , Jong Hee Kim a , Jung Bae Kim b a Korea Institute of Ceramic Engineering and Technology, Seoul 153-801, Republic of Korea b Department of Chemical and Biological Engineering, Korea University, Seoul 136-701, Republic of Korea article info Article history: Received 13 October 2010 Received in revised form 30 January 2011 Accepted 6 February 2011 Available online 12 February 2011 Keywords: Functionalized mesoporous silicas DNA separation Electrostatic interaction Solid-state NMR Confocal microscope abstract This work describes the development of highly efficient human DNA separation with functionalized mesoporous silica (FMS) materials. To demonstrate the electrostatic interaction effect between the target DNA molecules and FMS, three aminofunctionality types comprised of a mono-, a di-, and a tri- amine functional group were introduced on the inner surfaces of mesoporous silica particles. Systematic characterization of the synthesized materials was achieved by solid-state 29 Si and 13 C-NMR techniques, BET, FT-IR, and XPS. The DNA separation efficiency was explored via the function of the amino-group number, the amount used, and the added NaCl concentration. The DNA adsorption yields were high in terms of the use of triaminofunctionalized FMS at the 10 ng/L level, and the DNA desorption efficiency showed the optimum level at over 3.0 M NaCl concentration. The use of FMS in a DNA separation process provides numerous advantages over the conventional silica-based process. Crown Copyright & 2011 Published by Elsevier Inc. All rights reserved. 1. Introduction The application of silica and silica-based materials to life-science technologies is attracting attention from numerous research fields, including biotechnology, and nanomaterial science. These materials have been assessed as drug or gene delivery systems, bio-separation agents, diagnostic agents, and as sensors due to their high surface areas and straightforward surface modification [1–8]. One of the recent interests in bio-applications focused on the separation and purification of specific bio-pharmaceuticals such as DNA and protein from multi-component mixtures [9,10]. DNA separation is especially important for the sequencing of genomes, DNA fingerprinting, the identification of pathogens, and numerous types of genetic assays that are used to identify diseases. Current DNA separation methods engender several drawbacks that make them unsuitable for the manufacturing of pharmaceutical-grade materials. They often involve the use of some or all of the following: solvents; toxic chemicals such as cesium chloride, ethidium bromide, phenol, and chloroform; or animal-derived enzymes such as ribonuclease A and lysozyme that are either not approved or not recommended by regulatory agencies. Moreover, the research of the utilization of MNPs has been interesting and burgeoning in the fields of the bio-separation due to the convenient and time-saving process. Especially, iron-oxide-based magnetic nanomaterials have been used for the magnetic separation in DNA and proteome researches because of the good hydrophilicity, biocompatibility, and nontoxicity. However, the MNPs-based process suffers from the low separation efficiency due to the agglomeration and low surface reactivity. A common limitation of the commercial matrix is also the low capacity of DNA due to the inability of large molecules to penetrate porous beads, there have been no reports of a matrix being used to separate DNA simultaneously. Consequently, there is a need for large-scale processes to manufacture highly pure DNA, and the requirements of regulatory agencies regarding purity, potency, safety, and efficacy must be achieved. Hence, we tried to demonstrate novel approach with ordered mesoporous silica (MS) materials, in which they have the high surface areas by the homogeneous nanopores and channels. The lots of nanopores and high surface areas are suitable for enhance- ment of separation efficiency. Actually, the comparison of surface areas between MS and MNPs shows much difference; the MS has 800–1300 m 2 /g, but the MNPs has 10–30 m 2 /g. Furthermore, lots of silanol group ( OH) at the surface of MS are suitable for observation of electrostatic interaction between solid materials and target biomolecules by surface modification. In this work, we prepared poly-amino group assembled FMS as a function of the number of amino groups tailored for mono-, di-, and tri-aminofunctionality to demonstrate the highly efficient DNA separation efficiency. The application of FMS to DNA separa- tion research provides many immediate advantages, including higher surface-to-volume areas, enhanced binding efficiency, and Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jssc Journal of Solid State Chemistry 0022-4596/$ - see front matter Crown Copyright & 2011 Published by Elsevier Inc. All rights reserved. doi:10.1016/j.jssc.2011.02.005 n Corresponding author. E-mail address: jhchang@kicet.re.kr (J.H. Chang). Journal of Solid State Chemistry 184 (2011) 805–810