Carmen Maria Casado

This review summarizes contributions made by the authors between 1990 and 2025 in the design, synthesis, and application of redox-active organometallic dendrimers and polymers. Emphasis is placed on the progressive evolution from fundamental synthetic studies to functional devices, highlighting how dendritic architectures based on ferrocene and related units have provided a rich and adaptable platform at the interface of inorganic, polymer, and materials chemistry.

CdSe quantum dots nanoparticles were coated with the thiolated (DiAminoButane based dendrimer) DAB dendrimer of fifth generation (S-DAB₅) and embedded in a highly hydrophilic regenerated cellulose (RC) film by simple dip-coating method (immersion in QD-dendrimer aqueous solution) as a way to get a flexible nano-engineered film (RC-4/CdSe-QDs@S-DAB₅) with high transparency and photoluminescence properties for different applications. Optical changes in the RC film associated with QDs inclusion were determined by spectroscopic ellipsometry (SE) measurements, which provide information on changes caused in the refraction index and the extinction coefficients of the film, as well as by light transmittance/reflectance curves and photoluminescence (PL) spectra. Impedance spectroscopy (IS) and other typical physicochemical techniques for material characterization (TEM, SEM and XPS) have also been used in order to have more complete information on film characteristics. A comparison of RC-4/CdSe-QDs@S-DAB₅ film optical characteristics with those exhibited by other RC-modified films depending on the type of dendrimer was also carried out.

The in-situ synthesis of catalytic surfaces with metallic nanoparticles must overcome the issues related to particle aggregation and polydispersity in the particle size. This work achieves it by using two electrodeposited ferrocenyl polycyclosiloxane polymers (MFPP and FPP) as templates for electro-synthesize Pt nanoparticles (PtNPS). In addition, this new electrode surface combines two efficient electrocatalysts: Ferrocene and Pt nanoparticles, with synergistic biocatalytic properties that constitute an electrocatalytic framework for the covalent immobilization of xanthine oxidase. In this work, we present the results of the kinetic, electrochemical and analytical studies of the prepared electrodes. These results showed that the PtNPs/FPP system is the best bioelectrocatalytic surface and improves other more complex xanthine oxidase devices based on the hydrogen peroxide oxidation, allowing the use of lower measuring potential with good sensitivity, wider linear ranges and low detection limits. In addition, this electrode provides the novelty of allowing the measurement of xanthine through the enzymatic consumption of oxygen at potential −0.1 V with a sensitivity of 1.10 A M⁻¹ cm⁻², linear ranges of 0.01–0.1 and 0.1–1.4 mM, low detection limit (48 nM) and long-term stability. The new device has been successfully applied to the determination of xanthine in fish meat.

The main target of this work is the development of efficient hydrogen peroxide non-enzymatic sensors based on size-controlled gold nanoparticles from electrodeposited aminoferrocenyl dendrimer-templates. In this work we study the kinetics and electrochemistry of the modified electrodes as well as the kinetics and the analytical responses of them to both the oxidation and reduction of hydrogen peroxide via different processes related with the absence or presence of gold nanoparticles and their size. The best responses as non-enzymatic sensors were observed at 0.5 V with the largest nanoparticles, obtained from the first generation dendrimer-template, with two linear ranges (0.001–1.2 and 1.2–4.0 mM), sensitivities 249.5 and 185.6 μA/mM cm² and limit of detection of 0.07 μM; and at −0.2 V with the smallest ones, obtained from the fifth generation, with three linear ranges (0.001–2.0, 2.0–4.0 and 4.0–15.0 mM), sensitivities 172.1, 888.4 and 437.0 μA/mM cm² respectively_, and limit of detection of 0.06 μM. The non-enzymatic peroxide sensors showed an interference-free behavior at −0.2 V.

The main target of this work is the preparation of nanostructurated surfaces with size-controlled gold nanoparticles to obtain effective electrocatalytic surfaces. In this paper, we show that dispersed Au nanoparticles (AuNPs) having diameters of less than 3 nm can be synthesized in situ with aminoferrocenyl- and amidoferrocenyl-poly(propyleneimine) (PPI) dendrimers previously electrodeposited onto electrode surfaces. Dendrimers of first, third and fifth generation have been studied and good dispersed non aggregated nanoparticles were obtained in all the cases. In a similar way than in homogeneous media, inter-dendrimer Au nanoparticles have been obtained when first or third generation dendrimer modified electrodes were used, while smaller nanoparticles were obtained with fifth generation dendrimer, indicating that intra-dendrimer Au nanoparticles have been synthesized. The AuNPs were obtained from a HAuCl₄ solution after chemical reduction with NaBH₄. The formation of AuNPs was followed by UV-Vis spectroscopy; electrochemistry and ultra-high resolution scan electron microscopy (HRSEM). The obtained electrodes have been successfully used for the tetraelectronic oxygen reduction reaction (ORR) with a low onset potential (0.00 V vs. SCE), high kinetic current densities and also high heterogeneous electron transfer rate constants.