A versatile approach based on nanosphere lithography is proposed to generate surface‐imprinted polymers for selective protein recognition. A layer of 750 nm diameter latex bead‐protein conjugate is deposited onto the surface of gold‐coated quartz crystals followed by the electrosynthesis of a poly(3,4‐ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT/PSS) film with thicknesses on the order of the bead radius. The removal of the polymer bead‐protein conjugates, facilitated by using a cleavable protein‐nanosphere linkage is shown to result in 2D arrays of periodic complementary size cavities. Here it is demonstrated by nanogravimetric measurements that the imprinting proceeds further at molecular level and the protein (avidin) coating of the beads generates selective recognition sites for avidin on the surface of the PEDOT/PSS film. The binding capacity of such surface‐imprinted polymer films is ca. 6.5 times higher than that of films imprinted with unmodified beads. They also exhibit excellent selectivity against analogues of avidin, i.e., extravidin, streptavidin, and neutravidin, the latter being in fact undetectable. This methodology, if coupled with properly oriented conjugation of the macromolecular template to the nanoparticles, offers the possibility of site‐directed imprinting.

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Nanosphere lithography with nanosphere‐protein conjugates is proposed by R. E. Gyurcsányi and co‐workers as a generic method to create surface molecularly imprinted polymer films for selective protein recognition. , electrosynthesis of a polymer film in the voids of the nanosphere array followed by removal of the nanospheres generates complementary cavities bearing the imprints of the proteins.

Molecularly imprinted polymers bind their target compounds at binding sites. The binding sites are typically based on some type of functional group, such as carboxyl group. The total amount of such functional groups and their distribution into available and unavailable groups is not well known. The total binding capacity is usually indirectly determined from adsorption isotherms, which are measured much below the theoretical binding capacity. This work shows that in a variety of differently prepared, methacrylic acid based molecularly imprinted and nonimprinted polymers, all carboxylic groups used for the polymer synthesis are retained in the polymer, 80-90% of them can be accessed by strong bases and essentially the same amount can be used for adsorption of weak bases. This high level of adsorption can only be achieved, however, if the adsorbed weak base is strong enough, if the polymer is sufficiently elastic and if the solvent does not compete too strongly for the binding sites. These results may explain why the maximum binding capacities obtained from isotherm measurements are usually not equal to the total amount of available binding sites. This study confirms the usefulness of nonimprinted polymers at high loadings.

Selectivity is extremely important in analytical chemistry but its definition is elusive despite continued efforts by professional organizations and individual scientists. This paper shows that the existing selectivity concepts for univariate analytical methods broadly fall in two classes: selectivity concepts based on measurement error and concepts based on response surfaces (the response surface being the 3D plot of the univariate signal as a function of analyte and interferent concentration, respectively). The strengths and weaknesses of the different definitions are analyzed and contradictions between them unveiled. The error based selectivity is very general and very safe but its application to a range of samples (as opposed to a single sample) requires the knowledge of some constraint about the possible sample compositions. The selectivity concepts based on the response surface are easily applied to linear response surfaces but may lead to difficulties and counterintuitive results when applied to nonlinear response surfaces. A particular advantage of this class of selectivity is that with linear response surfaces it can provide a concentration independent measure of selectivity. In contrast, the error based selectivity concept allows only yes/no type decision about selectivity.

A simple and efficient method is presented for assessing molecularly imprinted polymers (MIP) and other sorbents from the point of view of practical applications. The adsorption isotherms of the compounds, which need to be separated or detected in an application, are constructed from a small number of measured points on a log-log chart and then are compared graphically. Despite its simplicity and robustness this method reveals the information needed for optimal selection between MIPs and alternative sorbents. The design of separation or detection methods with MIPs is also supported by the proposed graphical isotherm comparison. Many experimental isotherms are presented supporting the proposed method.

One of the main reasons for making molecularly imprinted polymers (MIPs) has been that MIPs interact selectively with a specific target compound. This claim is investigated here with the example of a widely used type of noncovalent MIP, the MIP for the beta blocker propranolol. Adsorption isotherms of this MIP and of a nonimprinted control polymer (NIP), respectively, have been measured with a series of compounds in the porogen solvent acetonitrile. The results, visualized as “selectivity ladders”, show that the MIP binds propranolol and many other amines better than the NIP does, but the selectivity of the MIP is actually inferior to that of the NIP. The selectivity of either polymer for propranolol is modest against many amines, but is remarkable with respect to other compounds. The contribution of imprinting towards selectivity can be better appreciated when three MIPs, made with different amine templates, are compared among themselves. Each MIP is seen to bind its own template slightly better than the other two MIPs do. In media different from the porogen, the selectivity patterns may change substantially. Propranolol seems to have properties that make it stand high on the selectivity scale in different solvents, albeit for different reasons.

Molecularly imprinted polymers (MIP) are a new generation of selective adsorbents. In practical applications of MIPs Keywords molecularly imprinted polymer, adsorption isotherm, competitive adsorption isotherm, propranolol, beta blocker IntroductionMolecularly imprinted polymers (MIP) are a new generation of selective adsorbents. They are the subject of vigorous research which produces hundreds of papers annually. After years of fundamental research the time appears to be ripe now for their practical applications. This is attested by the increasing number of patent applications (62 in MIPs are typically made by polymerization of suitable monomers in the presence of a so-called template compound. After polymerization the template is removed from the polymer. This procedure leaves empty binding sites in the polymer, which are chemical and geometrical imprints of the template molecule. Due to these sites the MIP can rebind from solutions the template or other molecules which are chemically related to the template. The rebinding on a good MIP occurs selectively against compounds which are not very closely related to the template. The target compound of a practical application can be either the template or a closely related compound (e.g. if the template is expensive or toxic or its bleeding would disturb). Eventually a group of closely related compounds to the template may be targeted.For successful practical applications one needs to know if the MIP will show sufficient selectivity. Quantification of selectivity is a difficult problem in chemistry, and particularly in analytical chemistry [20][21][22][23][24][25]. In the case of MIPs one may rely on a large body of experience in relation to chromatographic adsorbents. The selectivity of liquid chromatographic stationary phases is easily characterized (in a given eluent) if the adsorption isotherms of all adsorbed solutes are linear. In this case selectivity between two adsorbable compounds can be given by the ratio of the respective isotherm slopes, i.e., by the ratio of the respective,