Optimization of a glucose biosensor setup based on a Ni/Al HT matrix

Response Surface Methodology for the Optimisation of Electrochemical Biosensors for Heavy Metals Detection

Herein, we report the application of a chemometric tool for the optimisation of electrochemical biosensor performances. The experimental design was performed based on the responses of an amperometric biosensor developed for metal ions detection using the flow injection analysis. The electrode preparation and the working conditions were selected as experimental parameters, and thus, were modelled by a response surface methodology (RSM). In particular, enzyme concentration, flow rates, and number of cycles were reported as continuous factors, while the sensitivities of the biosensor (S, µA·mM-1) towards metals, such as Bi3+ and Al3+ were collected as responses and optimised by a central composite design (CCD). Bi3+ and Al3+ inhibition on the Pt/PPD/GOx biosensor response is for the first time reported. The optimal enzyme concentration, scan cycles and flow rate were found to be 50 U·mL-1, 30 and, 0.3 mL·min-1, respectively. Descriptive/predictive performances are discussed: the sensitivities of the optimised biosensor agreed with the experimental design prediction. The responses under the optimised conditions were also tested towards Ni2+ and Ag⁺ ions. The multivariate approach used in this work allowed us to obtain a wide working range for the biosensor, coupled with a high reproducibility of the response (RSD = 0.72%).

A review on electrochemical biosensing platform based on layered double hydroxides for small molecule biomarkers determination

The development of layered double hydroxides (LDHs), also known as anionic clays with uniform distribution of metal ions and facile exchangeability of intercalated anions, are now appealing an immense deal of attention in synthesis of multifunctional materials. In electrochemical biosensors, LDHs provide stable environment for immobilization of enzymes or other sensing materials and play crucial roles in development of clinical chemistry, point-of-care devices through analysis of various small molecule metabolites excreted by biological processes which in turn serve as molecular biomarkers for medical diagnostics. In this review, we summarize the recent development in fabrication of LDH based nanoarchitectures and their electrocatalytic applications in ultrasensitive in vitro determination of conventional biomarkers, i.e., H₂O₂, glucose, dopamine and other biomolecules. Moreover, detailed discussion has been compiled to differentiate electrochemical enzymatic and nonenzymatic biosensors, to evaluate useful concentration ranges of H₂O₂ and glucose for analytical circumstances and to distinguish tumorigenic and normal cells via quantifying the released H₂O₂ efflux from living cells. Here, we envision that electrochemical sensing platform based on structurally integrated LDH nanohybrids with highly conducting substrates will assist as diseases diagnostic probe further enhancing diagnosis as well as therapeutic window for chronic diseases. Finally, the perspective for fabrication and assembly of LDH electrode is proposed for the future innovation of electrochemical biosensors with high performance making them more reliable for in vitro diagnostics.

Layered-double-hydroxide-modified electrodes: electroanalytical applications

Two-dimensional inorganic solids, such as layered double hydroxides (LDHs), also defined as anionic clays, have open structures and unique anion-exchange properties which make them very appropriate materials for the immobilization of anions and biomolecules that often bear an overall negative charge. This review aims to describe the important aspects and new developments of electrochemical sensors and biosensors based on LDHs, evidencing the research from our own laboratory and other groups. It is intended to provide an overview of the various types of chemically modified electrodes that have been developed with these 2D layered materials, along with the significant advances made over the last several years. In particular, we report the main methods used for the deposition of LDH films on different substrates, the conductive properties of these materials, the possibility to use them in the development of membranes for potentiometric anion analysis, the early analytical applications of chemically modified electrodes based on the ability of LDHs to preconcentrate redox-active anions and finally the most recent applications exploiting their electrocatalytic properties. Another promising application field of LDHs, when they are employed as host structures for enzymes, is biosensing, which is described considering glucose as an example.

Biosensing applications of clay-modified electrodes: a review

Two-dimensional layered inorganic solids, such as cationic clays and layered double hydroxides (LDHs), also defined as anionic clays, have open structures which are favourable for interactions with enzymes and which intercalate redox mediators. This review aims to show the interest in clays and LDHs as suitable host matrices likely to immobilize enzymes onto electrode surfaces for biosensing applications. It is meant to provide an overview of the various types of electrochemical biosensors that have been developed with these 2D layered materials, along with significant advances over the last several years. The different biosensor configurations and their specific transduction procedures are discussed.

New polymeric composites based on poly(-caprolactone) and layered double hydroxides containing antimicrobial species

Benzoate (Bz), 2,4-dichlorobenzoate (BzDC), and p- and o-hydroxybenzoate (p- and o-BzOH) anions with antimicrobial activity have been intercalated into [Zn(0.65)Al(0.35)(OH)(2)](NO(3))(0.35).0.6H(2)O, layered double hydroxide (LDH), via anion-exchange reactions. The composition of the obtained intercalation compounds, determined by chemical, thermogravimetric, and ion chromatographic analyses, indicates that benzoate and benzoate derivative anions replace the nitrate counteranions, almost completely. Information on the interactions of the intercalated anions with the inorganic layer have been obtained from Fourier transform IR absorption spectroscopy and powder X-ray diffraction of the samples. It has been found that both the nature and the position of the aromatic ring substituents affect the value of the basal distance and the host-guest hydrogen bond network. Knowledge of the chemical composition, basal distance, and van der Waals dimensions of the guests has finally allowed the proposal of structural models of the intercalation compounds that have been used as fillers of poly(caprolactone), a biodegradable polymer. Films of polymeric composites were obtained by hot-pressing the powders of polymer and filler previously milled by a high-energy ball milling procedure. X-ray diffraction analysis and optical and scanning electron microscopy of the composites indicate that the LDH samples containing BzDC anions are delaminated into the polymeric matrix, whereas those containing p-BzOH anions maintain for the most part the crystal packing and give rise to microcomposites. Intermediate behavior was found for LDH modified with Bz and o-BzOH anions because exfoliated and partly intercalated composites were obtained. Preliminary antimicrobial tests indicate that the composites are able to inhibit the Saccharomyces cerevisiae growth of 40% in comparison with the growth in a pure culture medium. The composites can be studied as the model for "active packaging" systems because of the antimicrobial properties of the anions anchored to the LDH layer.