Elucidating the Molecular Structure of Hydrophobically Modified Polyethylenimine Nanoparticles and Its Potential Implications for DNA Binding

The structural properties of the polyethylenimine (PEI) polymer are generally tuned and selectively modified to reinforce its potential in a broad spectrum of applied domains of medicine, healthcare, material design, sensing, and electronic optimization. The selective modification of the polymer brings about changes in its interfacial characteristics and behavior. The current work involves the synthesis of naphthalimide conjugated polyethylenimine organic nanoparticles (NPEI-ONPs). The interfacial molecular structure of NPEI-ONPs is explored in an aqueous medium at pH 7.4 using surface tensiometry and sum-frequency generation vibrational spectroscopy (SFG-VS). The hydrophobic functionalization rendered a concentration-dependent surface coverage of NPEI-ONPs, where the SFG-VS analysis exhibited the molecular rearrangement of its hydrophobic groups at the interface. The interaction of NPEI-ONPs with double-stranded DNA (dsDNA) is carried out to observe the relevance of the synthesized nanocomposites in the biomedical domain. The bulk-specific studies (i.e., thermal denaturation, viscometry, zeta (ζ) potential, and ATR-FTIR) reveal the condensation of dsDNA in the presence of NPEI-ONPs, making its structure more compact. The interface-sensitive SFG-VS showcased the impact of the dsDNA and NPEI-ONP interaction on the interfacial molecular behavior of NPEI-ONPs at the air-aqueous interface. Our results exhibit the potential of such hydrophobically functionalized ONPs as promising candidates for developing biomedical sealants, substrate coatings, and other biomedical domains.

A fluorescent sensor for intracellular Zn2+ based on cylindrical molecular brushes of poly(2-oxazoline) through ion-induced emission

Poly(2-oxazoline) molecular brushes bearing enaminitrile receptors in the side chain ends exhibit good biocompatibility, excellent fluorescent selectivity for Zn²⁺, and possibility in detecting intracellular Zn²⁺.

Nanoparticles of chitosan conjugated to organo-ruthenium complexes

The synthesis of nanoparticles of conjugates of caffeic acid-modified chitosan with ruthenium arene complexes is described.

A well-defined alternating copolymer based on a salicylaldimine Schiff base for highly sensitive zinc(ii) detection and pH sensing in aqueous solution

We report a new strategy to fabricate well-defined alternating Schiff base copolymers of poly(VBCDEG-alt-SaAEMI)s which display two distinguishable color fluorescence “OFF–ON” responses to zinc ions and pH in aqueous solution.

“Turn-on” fluorescent chemosensor for zinc(ii) dipodal ratiometric receptor: application in live cell imaging

A dipodal ligand 2,2′-((ethane-1,2-diylbis(azanediyl))bis(ethane-1,1-diyl))diphenol was synthesized through a condensation reaction and was characterized with IR, ¹H NMR, ¹³C-NMR, and mass spectroscopy.