Biosensors and Bioelectronics 21 (2006) 2329–2338 Supported imprinted nanospheres for the selective recognition of cholesterol Gianluca Ciardelli a,c,∗ , Cristiana Borrelli a,1 , Davide Silvestri a , Caterina Cristallini b , Niccoletta Barbani a , Paolo Giusti a,b a Department of Chemical Engineering, Industrial Chemistry and Material Science, University of Pisa, via Diotisalvi 2, 56126 Pisa, Italy b C.N.R. Institute for Composite and Biomedical Materials, c.o Dept. Chemical Engineering, University of Pisa, Italy c Department of Mechanics, Politecnico of Turin, corso Duca degli Abruzzi 24 Turin, Italy Received 24 September 2005; received in revised form 30 November 2005; accepted 19 December 2005 Available online 29 March 2006 Abstract The preparation of innovative polymeric systems using molecular imprinting technology for application in extracorporeal blood purification is described. Membranes based on a methylmethacrylate-co-acrylic acid copolymer, produced through the phase inversion method, were modified introducing into their structure specific binding sites for cholesterol molecule by adding molecularly imprinted nanoparticles in the membrane matrix. Membranes prepared are intended to selectively remove cholesterol from the blood by using interactions at a molecular level, between the membrane/nanoparticles devices and the template, created during the preparation of polymers. Three polymeric systems in form of nanoparticles were prepared differing in the polymerisation solvent (a mixture of acetonitrile and ethanol (1:1) or pure ethanol), and the molar ratio between the functional monomer and the cross-linker (2.3:1 and 1:1). Two out of three of the prepared polymers showed a very good template rebinding capacity both in phosphate buffer solution (pH 6.9) and in ethanol. In particular the nanoparticles rebound 115.4 mg cholesterol/g polymer in buffer solution, and 57 mg cholesterol/g polymer in ethanol. The deposition of the nanoparticles on the surface of the phase inversion membranes produced devices with interesting rebinding performances towards cholesterol in buffer solution: a specific recognition of 14.09 mg cholesterol/g system (membrane and nanoparticles) was detected, indicating maintained binding capacity of supported particles as well. © 2006 Elsevier B.V. All rights reserved. Keywords: Molecular imprinting; Selective membranes; Imprinted nanoparticles; Cholesterol 1. Introduction Atherosclerosis is one of the major causes of morbidity and mortality in industrialized societies. While there has been sig- nificant advance in the treatment of atherosclerosis there is still a great need for more effective treatment interventions. The factors associated with atherosclerosis include: high levels of cholesterol, triglycerides, low density lipoproteins (LDL) and low levels of high density lipoproteins (HDL). A significant reduction in blood levels of cholesterol and LDL by diet and lipid reducing drugs was found to result in regres- ∗ Corresponding author. Tel.: +39 011 51646920; fax: +39 011 5646999. E-mail address: gianluca.ciardelli@ing.unipi.it (G. Ciardelli). 1 Present address: Institute of Environmental Research (INFU), University of Dortmund, Germany. sion of atherosclerosis (West of Scotland Coronary Prevention Study Group, 1998; Scandanavian Simvastatin Survival Study (4S) Group, 1994). However, oral lipid lowering drugs, such as statins, are risky and may cause liver damage; their efficacy is relatively limited, even when they are taken in association with a strict diet. A striking example is found in patients who have the homozygous form of familial hypercholesterolemia (FH) with extremely high levels of LDL-cholesterol even after an appropriate drug treatment. In these patients cholesterolemia can be reduced by specific removal of blood LDL; in practice the patient has to be treated once every 2–4 weeks by selective LDL-apheresis for 2–4 h. Lowering of LDL by extracorporeal treatment of blood is significantly more effective in reducing blood cholesterol and LDL levels and therefore coronary heart disease risk in severe types of FH patients (Borberg et al., 1983). Cholesterol and LDL 0956-5663/$ – see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2005.12.027