Nanomaterials Based on 2,7,12,17-Tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine Exhibiting Bifunctional Sensitivity for Monitoring Chloramphenicol and Co2

Monitoring antibiotic retention in human body fluids after treatment and controlling heavy metal content in water are important requirements for a healthy society. Therefore, the approach proposed in this study is based on developing new optical sensors using porphyrin or its bifunctional hybrid materials made with AuNPs to accomplish the accurate detection of chloramphenicol and cobalt. To produce the new optical chloramphenicol sensors, 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (TBAP) was used, both alone in an acid medium and as a hybrid material with AuNPs in a water-DMSO acidified environment. The same hybrid material in the unchanged water-DMSO medium was the sensing material used for Co2+ monitoring. The best results of the hybrid materials were explained by the synergistic effects between the TBAP azaporphyrin and AuNPs. Chloramphenicol was accurately detected in the range of concentrations between 3.58 × 10-6 M and 3.37 × 10-5 M, and the same hybrid material quantified Co2+ in the concentration range of 8.92 × 10-5 M-1.77 × 10-4 M. In addition, we proved that AuNPs can be used for the detection of azaporphyrin (from 2.66 × 10-5 M to 3.29 × 10-4 M), making them a useful tool to monitor porphyrin retention after cancer imaging procedures or in porphyria disease. In conclusion, we harnessed the multifunctionality of this azaporphyrin and of its newly obtained AuNP plasmonic hybrids to detect chloramphenicol and Co2+ quickly, simply, and with high precision.

Dual-template molecularly surface imprinted polymer on fluorescent metal-organic frameworks functionalized with carbon dots for ascorbic acid and uric acid detection

In this work, dual-template molecularly imprinted polymer surfaces imprinted on blue fluorescent Cr-based MOF (Cr-MOF) functionalized with yellow emissive carbon dots (Y-CDs) were prepared using l-ascorbic acid (AA) and uric acid (UA) as templates for simultaneous selective recognition of AA and UA. The as-prepared nanocomposite probe (Y-CDs/Cr-MOF@MIP) contains two recognition site cavities and emits a dual well-resolved fluorescence spectra when excited at 390 nm; blue emission (λ_em 450 nm) is due to Cr-MOF, and yellow emission (λ_em 560 nm) is due to Y-CDs. The yellow fluorescence emission of Y-CDs was quenched upon the addition of ascorbic acid, while Cr-MOF's emission remained unaffected. In the same way, the blue fluorescence emission of the Cr-MOFs was quenched in the presence of uric acid, while the yellow emission remained constant. Both emissions were quenched in a sample containing both AA and UA. This can be exploited to design a dual-template biosensor to detect UA and AA simultaneously. The Y-CDs/Cr-MOF@MIP sensor displayed a dynamic linear response for AA in the range 25.0 µM - 425.0 µM with a detection limit of 1.30 µM, and for UA in the range 25.0 µM - 425.0 µM with a detection limit of 1.10 µM. The dual-target probe Y-CDs/Cr-MOF@MIP was highly selective and sensitive for the detection of UA and AA in human urine samples due to the selectivity of the two recognition sites.

On the Use of Polymer-Based Composites for the Creation of Optical Sensors: A Review

Polymers are widely used in many areas, but often their individual properties are not sufficient for use in certain applications. One of the solutions is the creation of polymer-based composites and nanocomposites. In such materials, in order to improve their properties, nanoscale particles (at least in one dimension) are dispersed in the polymer matrix. These properties include increased mechanical strength and durability, the ability to create a developed inner surface, adjustable thermal and electrical conductivity, and many others. The materials created can have a wide range of applications, such as biomimetic materials and technologies, smart materials, renewable energy sources, packaging, etc. This article reviews the usage of composites as a matrix for the optical sensors and biosensors. It highlights several methods that have been used to enhance performance and properties by optimizing the filler. It shows the main methods of combining indicator dyes with the material of the sensor matrix. Furthermore, the role of co-fillers or a hybrid filler in a polymer composite system is discussed, revealing the great potential and prospect of such matrixes in the field of fine properties tuning for advanced applications.

Efficient Decrease in Corrosion of Steel in 0.1 M HCl Medium Realized by a Coating with Thin Layers of MnTa2O6 and Porphyrins Using Suitable Laser-Type Approaches

The purpose of this research is to meet current technical and ecological challenges by developing novel steel coating systems specifically designed for mechanical equipment used in aggressive acid conditions. Homogeneous sandwich-type layered films on the surface of steel electrodes were realized using a pseudo-binary oxide, MnTa₂O₆, and two different substituted porphyrin derivatives, namely: 5-(4-carboxy-phenyl)-10,15,20-tris (4-methyl-phenyl)-porphyrin and 5-(4-methyl-benzoate)-10,15,20-tris (4-methyl-phenyl)-porphyrin, which are novel investigated compound pairs. Two suitable laser strategies, pulsed laser deposition (PLD) and matrix-assisted pulsed laser evaporation (MAPLE), were applied in order to prevent porphyrin decomposition and to create smooth layers with low porosity that are extremely adherent to the surface of steel. The electrochemical measurements of corrosion-resistant coating performance revealed that in all cases in which the steel electrodes were protected, a significant value of corrosion inhibition efficiency was found, ranging from 65.6 to 83.7%, depending on the nature of the porphyrin and its position in the sandwich layer. The highest value (83.7%) was obtained for the MAPLE/PLD laser deposition of 5-(4-carboxy-phenyl)-10,15,20-tris (4-methyl-phenyl)-porphyrin/MnTa₂O₆(h), meaning that the inhibitors adsorbed and blocked the access of the acid to the active sites of the steel electrodes.