Adsorption affinity of certain biomolecules onto polymeric resins: Effect of solute chemical nature Monali Dutta Saikia a, * , N.N. Dutta b a Department of Chemistry, Indian Institute of Technology, Guwahati, North Guwahati 781 039, Assam, India b Department of Chemical Engineering, Indian Institute of Technology, Guwahati, North Guwahati 781 039, Assam, India Received 1 August 2006; received in revised form 20 April 2007; accepted 22 October 2007 Available online 3 December 2007 Abstract The adsorption of certain biomolecules from aqueous solution on two polymeric adsorbents namely Amberlite XAD-4 and XAD-7 was studied in order to assess the effect of solute chemical nature. Adsorption affinity quantified as the slope of the linear region of the isotherm correlates well with important molecular properties of the solutes such as hydrophobicity, van der Waals interaction parameter and molecular connectivity. A novel correlating parameter could be derived from the molecular connectivity which provides topological description in terms of branching index and fundamental treatment of the molecular structure based on a valence weighted graph of the structural formula of a compound. Moreover, study reveals interplay between different driving forces in adsorption of biomolecules on polymeric resin. Ó 2007 Elsevier Ltd. All rights reserved. Keywords: Adsorption; Biomolecules; Hydrophobicity; Molecular connectivity; Van der Waals interaction 1. Introduction To improve the efficiency of recovery, separation, and purification from fermentation broths, several separation techniques have been employed [1,2]. When the energy efficiency, selectivity, and cost are considered, the adsorption based separation technique is a promising method for the separation of the biomolecules. In comparison to extraction, the high concentrating abilities of adsorption have been exploited especially for the more efficient removal of solute from dilute aqueous solutions [3]. The recent development of polymeric materials with well defined surface chemistries has provided opportunity to develop sorbents that can bind through only very narrowed mechanisms. By limit- ing the number of possible interaction mechanisms, it is possible to design more selective sorbents. During the past few years, quantitative structure activity relationship (QSAR) has gained consider- able importance in developing models for prediction of different physical and physicochemical phenome- non. Molecular descriptors such as molecular con- nectivity, polarizability, etc. can be easily calculated solely from the molecular structure [4,5] and may be applied for the prediction of certain adsorption properties [6–8]. Though we have been studying 1381-5148/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.reactfunctpolym.2007.10.013 * Corresponding author. Tel.: +91 361 2582316; fax: +91 361 2690762. E-mail addresses: monali@iitg.ernet.in, monalisaikia@hot- mail.com (M.D. Saikia). Available online at www.sciencedirect.com Reactive & Functional Polymers 68 (2008) 33–38 www.elsevier.com/locate/react REACTIVE & FUNCTIONAL POLYMERS