Molecular Imprinting in Thin Films of Organic−Inorganic Hybrid Sol−Gel and Acrylic Polymers

Abstract

The molecular imprinting technique was applied on a model compound, propranolol, using two polymeric systems, acrylic and hybrid organic-inorganic sol-gels. The polymers were applied as thin films on glass substrates. The preparation of thin films of imprinted acrylic polymers required the development of a new polymerization system. The binding properties of the two polymers toward propranolol were characterized by radioactive and fluorimetric assay procedures. The acrylic system was found to have high uptake toward propranolol, but this was accompanied by a high degree of nonspecific binding. The sol-gel system had lower uptake, but remarkably lower nonspecific binding (<10%). The K d of the sol-gel matrix to propranolol is 80 ( 6 nM, a value that is common in biological systems. The binding was found to be solvent sensitiveswith high affinity and specificity in aqueous solution, which was completely lost in organic solvents. The uptake kinetics of the acrylic polymer was significantly slower than the sol-gel polymer, reaching saturation after 10 h, relative to <1 h for the sol-gel polymer. Imprinting of the sol-gel film with enantiomerically pure (S)propranolol resulted in its pronounced chiral recognition over the (R)-enantiomer.

Imidazolium-based functional monomers for the imprinting of the anti-inflammatory drug naproxen: Comparison of acrylic and sol–gel approaches

“…Excess acetonitrile was distilled off using rotary evaporator and the resulting product was isolated as a lightbrown liquid. Product's characterization by 1 H NMR, 13 C NMR and LC-MS, allowed to obtain data (see below) in perfect agreement with both the expected structure and previously published NMR data for the same compound [15]. 1 …”

“…A minimal number of reports [10,13] regarding comparison of acrylic and sol-gel systems can be found in the literature. Cummins et al [10], compared the bulk acrylic and sol-gel systems for the imprinting of 2-aminopyridine; these authors replicated the acrylic MIP synthesized by Zhou and He [14], while used commercially available monomers as phenyltrimethoxysilane (PTMOS) and aminopropyltrimethoxysilane (APTES) for the synthesis of the sol-gel MIX.…”

“…In acetonitrile and methanol, however, both materials behaved similarly. In another work, Marx et al [13], used propanolol as model template for the comparison of the acrylic and sol-gel systems; they prepared MIP and MIX as films that were tested for their enantiomeric separation ability. The acrylic system was prepared using the typical polymerization mixture of MAA and ethyleneglycoldimethacrylate (EDMA), whereas PTMOS was used as the functional monomer for the sol-gel approach.…”

The Creation and Evaluation of Novel Canine Training Aids for Cocaine Using Molecularly Encapsulated Sol-Gel Polymers and an Investigation of Canine Field Accuracy

“…In addition, a sol-gel polymer's thickness, porosity, and surface area can easily be manipulated, increasing its versatility for a variety of applications. 75,83 Sol-gel encapsulation, or encapsulation within a sol-gel polymer, has recently been used for the entrapment of proteins and biosensors successfully. 81,82 Sol-gel polymers have become popular for encapsulation not only because of thermal stability and pore size distribution and manipulation, but also because of their variety of forms that are producible, such as glass, fibers, films, and powders.…”

“…It was not until the mid1970s that sol-gel chemistry began to be studied extensively and has been found to be a successful method to form homogenous, high purity inorganic products finding use as various products including molded gels, thin films, coatings, and molecular cages, to name a few. 82,83,[89][90][91][92] The sol-gel chemical process describes the evolution of a sol-solution into a gel.…”