The high interest in N-heterocyclic platinum carbene complexes in cancer research stems from their high cytotoxicity to human cancer cells, their stability, as well as their ease of functionalization. However, the development of these new molecules as anticancer agents still faces multiple challenges, in particular solubility in aqueous media. Here, we synthesized platinum-NHC bioconjugates that combine water-solubility and cytotoxicity by using polyethyleneimine as polymer carrier. We showed that the activity of these conjugates is modulated by the size of the polymer and the overall density of metal ions onto polymer chains. They displayed an effective activity after only 45 minutes of exposure in vitro correlated with a quick uptake by the cells as shown by the use of various fluorescent-tagged derivatives.

Polyethyleneimine (PEI) has been reported to have good potential for the adsorption of metal ions. In this work, PEI was covalently bound to NiFe2O4@SiO2 nanoparticles to form the new adsorbent NiFe2O4@SiO2–PEI. The material allowed magnetic separation and was characterized via powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform IR spectroscopy (FT-IR), and thermogravimetry-differential thermal analysis (TGA-DTA). The adsorption of CrO42‒, Ni2+, and Pb2+ ions from aqueous solutions was studied at different pH, temperatures, metal ion concentration, and adsorbent dosage. Maximum adsorption capacities of 149.23, 156.68, and 161.25 mg/g were obtained for CrO42‒, Ni2+, and Pb2+, respectively under optimum conditions using 0.075 g of the adsorbent material 250 mg/L ion concentration, at pH = 6.5 and room temperature.

Positively charged polyelectrolytes hold significant potential as materials for creating antibacterial coatings. Water-soluble macromolecules can be easily deposited onto a treated surface through various techniques, forming a film that provides antimicrobial properties to the surface through electrostatic interactions with bacterial membranes. The structural and molecular weight characteristics of the polymers play a crucial role in the physical and mechanical properties of the coatings. In this study, we investigated the properties of branched polyethyleneimine (PEI) and linear polydiallyldimethylammonium chloride (PDADMAC) coatings with different molecular weights of polymer samples to determine their suitability as stable coatings with antibacterial properties against foodborne bacteria. Using thermogravimetric analysis, dynamometry, and dynamic light scattering, we examined the physicochemical and mechanical properties of the macromolecules in water solutions and in coatings. Microbiological study was conducted to analyze the biocidal activity of the polycations in solutions and on the surface of coatings. Our findings showed that the moisture saturation of the polycationic coatings did not significantly depend on the chemical nature of charged groups or the molecular weight or architecture of macromolecules. Moreover, biocidal activity was not found to depend on the molecular weights of PEI and PDADMAC. However, the lowering of the molecular weight of polymers resulted in the loss of cohesive forces in the coatings and to dramatically loss of the stability towards wash-off with water. The diffusion coefficient (D0) of macromolecules was identified as a key parameter for the wash-off mechanism. Films formed by molecules with D0 below 1×10-7 cm2/s demonstrated high resistance to wash-off procedures. We demonstrated that PEI and PDADMAC samples with high molecular weights showed high antimicrobial activity towards L. monocytogenes. Our results highlight the importance of macromolecule characteristics in the development of new biocidal coatings based on polycations.