Design of Promising aza-BODIPYs for Bioimaging and Sensing

The obtainment of new luminophores for molecular sensorics of biosystems is becoming one of the urgent tasks in the field of chemical synthesis. The solution to each practical problem imposes its own limitations in the design of new structures with practically useful properties. The relationship between the structure and spectral properties is still to be unveiled. Three aza-BODIPY complexes with substituents of different natures were studied using time-resolved and steady-state fluorescence and absorption spectroscopy. The solvatochromic properties of aza-BODIPYs were studied with the use of a combined polyparametric approach and analysis by chemoinformatics methods for the first time. It was found that red shift of aza-BODIPY dyes was due to the increase of their structural lability. Predictive and experimental methods showed that the investigated aza-BODIPYs exhibited a positive solvatochromic effect, in contrast to classic BODIPYs (bearing C in the meso-position of the dipyrromethene core), which represents the negative solvatochromic properties. Spectral maxima in the area of the therapeutic window, low and predictable solvatochromism, and the ability to fine-tune the spectral characteristics make the investigated aza-BODIPYs promising scaffolds for the construction of bioengineering devices. Generalizations on the aza-BODIPYs’ design patterns were made in accordance with further bioimaging applications

Chemical Structural Coherence Principle on Polymers for Better Adhesion

Composite materials are the most variative type of materials employed in almost every task imaginable. In the present study, a synthesis of a novel perfluoroalkyltriethoxysilane is reported to be used in creating composites with polyhexafluoropropylene—one of the most indifferent and adhesion-lacking polymers existing. The mechanism of adhesion of hexafluoropropylene is proved to be due to chemical structural coherence of perfluoroalkyltriethoxysilane to a link of polyhexafluoropropylene chain. The ability of perfluoroalkyltriethoxysilane to attach to surfaces was studied by FT-IR spectroscopy of modified glass microspheres. Although the perfluoroalkyltriethoxysilane surface modifier allowed partial adhesion of polyhexafluoropropylene, some detachment took place; therefore, the surface nanostructuring was used to increase its specific area by aluminum foil anodizing. An anodized aluminum surface was studied by scanning electron microscopy. The resulting composite consisting of anodized aluminum, perfluoroalkyl surface modifier, and polyhexafluoropropylene layer was proved to be stable, showed no signs of detachment, and is a promising material for usage in harsh environments

Modified Nanodiamonds as a Means of Polymer Surface Functionalization. From Fouling Suppression to Biosensor Design

The development of different methods for tuning surface properties is currently of great interest. The presented work is devoted to the use of modified nanodiamonds to control the wetting and biological fouling of polymers using optical sensors as an example. We have shown that, depending on the type of modification and the amount of nanodiamonds, the surface of the same fluorinated polymer can have both bactericidal properties and, on the contrary, good adhesion to the biomaterial. The precise control of wetting and biofouling properties of the surface was achieved by the optimization of the modified nanodiamonds thermal anchoring conditions. In vitro and in vivo tests have shown that the fixation of amine functional groups leads to inhibition of biological activity, while the presence of a large number of polar groups of mixed composition (amide and acid chloride) promotes adhesion of the biomaterial and allows one to create a biosensor on-site. A comprehensive study made it possible to establish that in the first 5 days the observed biosensor response is provided by cells adhered to the surface due to the cell wall interaction. On the 7th day, the cells are fixed by means of the polysaccharide matrix, which provides much better retention on the surface and a noticeably greater response to substrate injections. Nevertheless, it is important to note that even 1.5 h of incubation is sufficient for the formation of the reliable bioreceptor on the surface with the modified nanodiamonds. The approach demonstrated in this work makes it possible to easily and quickly isolate the microbiome on the surface of the sensor and perform the necessary studies of its substrate specificity or resistance to toxic effects

Oligohexamethylene Guanidine Derivative as a Means to Prevent Biological Fouling of a Polymer-Based Composite Optical Oxygen Sensor

The use of biocidal agents is a common practice for protection against biofouling in biomass-rich environments. In this paper, oligohexamethyleneguanidine (OHMG) polymer, known for its biocidal properties, was further modified with para-aminosalicylic acid (PAS) to enhance its properties against microorganisms coated with a lipid membrane. The structure of the product was confirmed by 1H NMR, 13C NMR, and FTIR spectroscopy. The values of the minimum inhibitory concentration (MIC) against Mycobacterium smegmatis ATCC 607 and Pseudomonas chlororaphis 449 were found to be 1.40 and 1.05 μg/mL, respectively. The synthesized substance was used as an additive to the polymer matrix of the composite optical oxygen sensor material. A series of samples with different contents of OHMG-PAS was prepared using a co-dissolution method implying the fabrication of a coating from a solution containing both polymers. It turned out that the mutual influence of the components significantly affects the distribution of the indicator in the matrix, surface morphology, and contact angle. The optimal polymer content turned out to be wt.3%, at which point the water contact angle reaches almost 122°, and the fouling rate decreases by almost five times, which is confirmed by both the respiratory MTT assay and confocal microscopy with staining. This opens up prospects for creating stable and biofouling-resistant sensor elements for use in air tanks or seawater