https://www.selleckchem.com/products/on123300.html Linear polyethylenimines are polycationic excipients that have found many pharmaceutical applications, including as a delivery vehicle for gene therapy through formation of polyplexes with oligonucleotides. Accurate quantitation of linear polyethylenimines in both starting solution and formulation containing oligonucleotide/polyethylenimine polyplexes is critical. Existing methods using spectroscopy, matrix-assisted laser desorption/ionization mass spectrometry time-of-flight, or nuclear magnetic resonance are either complex or suffer from low selectivity. Here, the development and performance of a simple analytical method is described whereby linear polyethylenimines are resolved by ultra-high-performance liquid chromatography and quantified using either a charged aerosol detector or an ultraviolet detector. For formulated oligonucleotide/polyethylenimine polyplexes, sample preparation through decomplexation/digestion by trifluoroacetic acid was necessary to eliminate separation interference. The method can be used not only to support formulation development but also to monitor the synthesis/purification and characterization of linear polyethylenimines.The therapeutic potential of human mesenchymal stromal cells (h-MSC) is dependent on the viability and secretory capacity of cells both modulated by the culture environment. Our previous studies introduced heparin and collagen I (HEP/COL) alternating stacked layers as a potential substrate to enhance the secretion of immunosuppressive factors of h-MSCs. Herein, we examined the impact of HEP/COL multilayers on the growth, morphology, and secretome of bone marrow and adipose-derived h-MSCs. The physicochemical properties and stability of the HEP/COL coatings were confirmed at 0 and 30 days. Cell growth was examined using cell culture media supplemented with 2 and 10% serum for 5 days. Results showed that HEP/COL multilayers supported h-MSC growth in 2% serum at levels