Discrimination of Milks with a Multisensor System Based on Layer-by-Layer Films

Abstract

A nanostructured electrochemical bi-sensor system for the analysis of milks has been developed using the layer-by-layer technique. The non-enzymatic sensor [CHI+IL/CuPcS]2, is a layered material containing a negative film of the anionic sulfonated copper phthalocyanine (CuPcS) acting as electrocatalytic material, and a cationic layer containing a mixture of an ionic liquid (IL) (1-butyl-3-methylimidazolium tetrafluoroborate) that enhances the conductivity, and chitosan (CHI), that facilitates the enzyme immobilization. The biosensor ([CHI+IL/CuPcS]2-GAO) results from the immobilization of galactose oxidase on the top of the LbL layers. FTIR, UV–vis, and AFM have confirmed the proposed structure and cyclic voltammetry has demonstrated the amplification caused by the combination of materials in the film. Sensors have been combined to form an electronic tongue for milk analysis. Principal component analysis has revealed the ability of the sensor system to discriminate between milk samples with different lactose content. Using a PLS-1 calibration models, correlations have been found between the voltammetric signals and chemical parameters measured by classical methods. PLS-1 models provide excellent correlations with lactose content. Additional information about other components, such as fats, proteins, and acidity, can also be obtained. The method developed is simple, and the short response time permits its use in assaying milk samples online.

Multisensor Systems and Arrays for Medical Applications Employing Naturally-Occurring Compounds and Materials

“…Most of the natural polymers, e.g., gelatin, collagen, chitosan, cellulose and its acetate are applied for this purpose [ 57 ]. Chitosan, a biological polysaccharide polymer, is widely used in MSAs and MSSs [ 58 , 59 , 60 ], while other naturally-occurring compounds are used mainly in studies of single analyte sensors [ 57 ].…”

“…Although redox mediation is well known, in recent years, several new types such mediators were designed and studied [ 62 , 63 ]. As stated above, mediators are also used in MSAs and MSSs [ 43 , 59 , 64 ].…”

Decomposition of Glucose-Sensitive Layer-by-Layer Films Using Hemin, DNA, and Glucose Oxidase

“…At pH and ionic strengths close to physiological conditions, it was possible to slowly decompose the LbL film at low glucose concentrations of 1-10 mM.Polymers 2020, 12, 319 2 of 12 by the reaction of substrates and oxidases. LbL films composed of oxidases have been applied in biosensors and stimuli-responsive devices [31][32][33]. In the present work, we report the preparation of thin LbL films consisting of H-PEI and DNA with glucose oxidase (GOx), and the glucose-induced decomposition of these LbL film (Figure 1).…”

Multilayered Nanostructures Integrated with Emerging Technologies

“…Salvo-Comino et al have used LbL films fabricated by spin-coating process and electrochemical characterization in milk analysis [8]. They have used LbL architectures based on chitosan (CHI), 1-butyl-3-methylimidazolium tetrafluoroborate (IL), copper(II) tetrasulfonated phthalocyanines (CuPc S ), and galactose oxidase (GAO).…”