The water-soluble porphyrin, known as 5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphyrin (TMPyP), was successfully stabilized onto a carbon paste electrode (CP) by covering up the TMPyP-modified surface with a layer of ionic liquid (IL), particularly 1-butyl-3-methyl imidazolium hexafluorophosphate (BMim PF₆) or 1-butyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide (BMim NTf₂). Noncovalent interactions established between TMPyP and ILs combined with the hydrophobicity of the latter yielded a new class of modified electrodes, denoted as CP/TMPyP/IL. These new systems exhibited higher electroactive areas as compared to those of CP and CP/IL electrodes, as well as a stable and reproducible electrochemical behavior in aqueous solutions. The obtained CP/TMPyP/BMim PF₆ and CP/TMPyP/BMim NTf₂ electrodes were used as electrochemical sensors for nitrite oxidation. The positive results showed that these electrodes can be considered as an alternative for nitrite detection in the concentration range under investigation.

Silver nanoparticles (AgNPs) were synthetized and employed in surface-enhanced Raman scattering measurements to study the chemical behavior when thiacloprid (Thia) interacts with the surface of Ag nanospheres (AgNSp) and Ag nanostars (AgNSt) upon excitation of the system with a 785 nm laser. Experimental results show that the deactivation of the localized surface plasmon resonance induces structural changes in Thia. When AgNSp are used, it is possible to observe a mesomeric effect in the cyanamide moiety. On the other hand, when AgNSt are employed, it promotes the cleavage of the methylene (−CH2−) bridge in Thia to produce two molecular fragments. To support these results, theoretical calculations based on topological parameters described by the atoms in molecules theory, Laplacian of the electron density at the bond critical point (∇2ρ BCP), Laplacian bond order, and bond dissociation energies were made, confirming that the bond cleavage is centered at the −CH2– bridge in Thia.

The development of new biomaterials has gained increasing attention in the last decade. One of the most important aspects in the development of these new materials is to understand the chemical cues presents in the native niche. Among all the techniques currently available for measuring those interactions, Raman spectroscopy offers a unique and non-invasive tool for exploring the behavior of the components within a given biomaterial and their surrounding microenvironment. This technique exploits the unique molecular vibrational fingerprints for pinpointing those interactions. The vibrational response can be improved to the single molecule level, in the presence of metal nanoparticles (NPs) with plasmonic properties (silver, gold and copper) in the so-called Surface-Enhanced Raman Scattering (SERS), which can be used for in-situ measurements. Another technique recently developed is the Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS), which overcomes signal contamination from chemical interactions between biomolecules and the metal surface; it does this by coating the metal surface with an inert layer of alumina or silica. In the present contribution, the role and the applications of Raman, SERS and related spectroscopic techniques in the study of biomolecules in biomaterials are reviewed and discussed.

Three photobicyclized benzodithienoquinolizinium tetrafluoroborates (BPDTQBF4) were prepared and evaluated by UV–Vis and fluorescence spectral, electrochemical analysis, and by theoretical calculations as possible organic n-type semiconductors. Evaluation and comparison of their LUMO levels, HOMO-LUMO energy gaps as monomeric and π-stacked dimers with those of other materials, suggest their potential as organic n-type semiconductors. Calculations of their relative charge carrier mobilities confirmed this potential for one derivative with a long (C-14) alkyl chain appended to the polycyclic planar π-system.

Human performance enhancing drugs (PEDs), frequently used in sport competitions, are strictly prohibited by the World Anti-Doping Agency (WADA). Biological samples collected from athletes and regular patients are continuously tested regarding the identification and/or quantification of the banned substances. Current work is focused on the application of a new analytical method, molecularly imprinted nanoparticles (nanoMIPs), to detect and determine concentrations of certain prohibited drugs, such as β-blockers, in water and human urine samples. These medications are used in the treatment of cardiovascular conditions, negative effects of adrenaline (helping to relief stress), and hypertension (slowing down the pulse and softening the arteries). They can also significantly increase muscle relaxation and improve heart efficiency. The new method of the detection and quantification of β-blockers is based on synthesis, characterization, and implementation of nanoMIPs (so-called plastic antibodies). It offers numerous advantages over the traditional methods, including high binding capacity, affinity, and selectivity for target molecules. Additionally, the whole process is less complicated, cheaper, and better controlled. The size and shape of the nanoMIPs is evaluated by dynamic light scattering (DLS) and transmission electron microscope (TEM). The affinity and selectivity of the nanoparticles are investigated by competitive pseudo enzyme-linked immunosorbent assay (pseudo-ELISA) similar to common immunoassays employing natural antibodies. To provide reliable results towards either doping detection or therapeutic monitoring using the minimal invasive method, the qualitative and quantitative analysis of these drugs is performed in water and human urine samples. It is demonstrated that the assay can detect β-blockers in water within the linear range 1 nmol·L⁻¹–1 mmol·L⁻¹ for atenolol with the detection limit 50.6 ng mL⁻¹, and the linear range 1 mmol·L⁻¹–10 mmol·L⁻¹ for labetalol with the detection limit of 90.5 ng·mL⁻¹. In human urine samples, the linear range is recorded in the concentration range 0.1 mmol·L⁻¹–10 nmol·L⁻¹ for atenolol and 1 mmol·L⁻¹–10 nmol·L⁻¹ for labetalol with a detection limit of 61.0 ng·mL−1 for atenolol and 99.4 ng·mL⁻¹ for labetalol.

Carbon paste electrodes modified with a family of ionic liquids (as binders) derived from N-octyl-pyridinium hexafluorophosphate, (composite-ionic liquid electrodes (CILEs)) were studied toward the oxidation of sulfite as an inner-sphere probe reaction and compared to a conventional carbon paste electrode (CPE) in which the binder was mineral oil. The ionic liquids were modified at para-position with substituents that are electron withdrawing: -CN (CILE/CN) and −CF₃ (CILE/CF₃) and substituents that are electron donating: -CH₃ (CILE/CH₃) and −OCH₃ (CILE/OCH₃), and compared with the ionic liquid without substituents (CILE/OPy). The results showed that CILEs are capable of catalyzing the sulfite oxidation, shifting the oxidation potential to more negative values compared to CPE. Also, they showed linear correlations between increasing sulfite concentration and increasing current density. The best system in terms of sensitivity was the electrode modified with the 4-methyl-N-octylpyridiniumhexafluorophosphate CILE/CH₃ and, then, that modified with the non-substituted ionic liquid CILE/OPy measured by amperometry. In terms of potential, the best systems are the CILEs modified with ILs with inductive-substituents, -CH₃ and −CF₃ and OPy, indicating that the delocalization of the charge of the cation produced by the mesomeric-substituent (-OCH₃, -CN) diminishes the electrocatalytic behavior of these binders for that oxidation. On the other hand, the analytical parameters of all the amperometric sensors studied here (all CILEs excepts CILE/OCH₃) are good enough to be applied in food industry for samples without polyphenols at concentrations higher than ca. 1mM of sulfite. Their stability is very high (at least 100 cycles after obtaining a stable response without changing its current, exposed to air and humidity) and they can be used to remove sulfite from wastewaters. Finally, to our knowledge, there are not comparative studies about the effect of changing the substituent of the cation in electrocatalysis of modified IL-electrodes.