The p53 protein is a transcription factor that preserves the integrity of the genome. The TP53 gene has inactivating mutations in about 50% of all human cancers. Some missense mutations lead to decreased thermal stability in the p53 protein, its unfolding and aggregation under physiological conditions. A general understanding of the impact of point mutations on the stability and conformation of mutant p53 is essential for the design and development of small molecules that target specific p53 mutations. In this work, we determined the thermostability properties of some of the most common mutant forms of the p53 protein—p53(R273H), p53(R248Q), p53(R248W) and p53(Y220C)—that are often considered as attractive therapeutic targets. The results showed that these missense mutations lead to destabilization of the p53 protein and a decrease in its melting temperature.

Sensitive systems with controlled release of drugs or diagnostic markers are attractive for solving the problems of biomedicine and antitumor therapy. In this study, new decasubstituted pillar[5]arene derivatives containing L-Tryptophan and L-Phenylalanine residues have been synthesized as pH-responsive drug nanocarriers. Fluorescein dye (Fluo) was loaded into the pillar[5]arene associates and used as a spectroscopic probe to evaluate the release in buffered solutions with pH 4.5, 7.4, and 9.2. The nature of the substituents in the pillar[5]arene structure has a huge influence on the rate of delivering. When the dye was loaded into the associates based on pillar[5]arene derivatives containing L-Tryptophan, the Fluo release occurs in the neutral (pH = 7.4) and alkaline (pH = 9.2) buffered solutions. When the dye was loaded into the associates based on pillar[5]arene with L-Phenylalanine fragments, the absence of release was observed in every pH evaluated. This happens as the result of different packing of the dye in the structure of the associate. This fact was confirmed by different fluorescence mechanisms (aggregation-caused quenching and aggregation-induced emission) and association constants. It was shown that the macrocycle with L-Phenylalanine fragments binds the dye more efficiently (lgKa = 3.92). The experimental results indicate that the pillar[5]arene derivatives with amino acids fragments have a high potential to be used as a pH-responsive drug delivery devices, especially for promoting the intracellular delivering, due to its nanometric size.

The present work focuses on the study of the aggregation and complexing properties of calixarenes as potential DNA condensation agents for gene delivery. In the current study, 1,4-triazole derivatives of calix[4]arenes 7 and 8 containing monoammonium fragments were synthesized. The synthesized compound’s structure was characterized by using various spectroscopic techniques (FTIR, HRESI MS, ¹H NMR and ¹³C NMR). The interactions between a series of calix[4]arene-containing aminotriazole groups (triazole-containing macrocycles with diethylenetriammonium fragments (3 and 4) and triazole-containing macrocycles with monoammonium fragments (7 and 8)) and calf thymus DNA were carried out via UV absorption, fluorescence spectroscopy, dynamic light scattering and zeta potential measurements. The role of the binding forces of calixarene–DNA complexes was analyzed. Photophysical and morphological studies revealed the interaction of the calixarenes 3, 4 and 8 with ct-DNA, which transformed the fibrous structure of ct-DNA to completely condensed compact structures that are 50 nm in diameter. The cytotoxic properties of calixarenes 3, 4, 7 and 8 against cancerous cells (MCF7, PC-3) as well as a healthy cell line (HSF) were investigated. Compound 4 was found to have the highest toxic effect on MCF7 breast adenocarcinoma (IC50 3.3 μM).