Poly(l-lysine)-Coated Liquid Crystal Droplets for Sensitive Detection of DNA and Their Applications in Controlled Release of Drug Molecules

Abstract

Interactions between DNA and adsorbed poly(l-lysine) (PLL) on liquid crystal (LC) droplets were investigated using polarizing optical microcopy and epi-fluorescence microscopy. Earlier, we demonstrated that adsorption of PLL to the LC/aqueous interface resulted in homeotropic orientation of the LC and thus exhibited a radial configuration of the LC confined within the droplets. Subsequent adsorption of DNA (single-stranded DNA/double-stranded DNA) at PLL-coated LC droplets was found to trigger an LC reorientation within the droplets, leading to preradial/bipolar configuration of those droplets. To our surprise, subsequent exposure of complementary ssDNA to ssDNA/adsorbed PLL-modified LC droplets did not cause the LC reorientation. This is likely due to the formation of polyplexes (DNA–PLL complex) as confirmed by fluorescence microscopy and atomic force microscopy. In addition, dsDNA-adsorbed PLL droplets have been found to be effectively useful to displace (controlled release) propidium iodide (a model drug) encapsulated within dsDNA over time. These observations suggest the potential for a label-free droplet-based LC detection system that can respond to DNA and may provide a simple method to develop DNA-based drug nanocarriers.

RETRACTED ARTICLE: Degradable poly-L-lysine-modified PLGA cell microcarriers with excellent antibacterial and osteogenic activity

“…Because of the positive interaction between the positive charge on the PLL surface and the negative charge on the cell membrane surface, PLL is often used as a surface modification method to enhance cell adhesion [16]. Furthermore, PLL exhibits a strong interaction with negatively charged molecules and high biofilm permeability, which has a wide range of applications in the medical field [17,18]. More importantly, this surface modification method is convenient and simple, and shows great application value in biomaterial applications.…”

“…PLL coating has been shown to facilitate the binding of bioactive factors and polymer materials [22]. This surface immobilization method has been applied to the controlled release and delivery of various bioactive factors, such as DNA, drugs, miRNA and nerve growth factor (NGF), [17,23,24]. Therefore, PLL coating not only is a surface modification method to enhance the bioactivity of cell microcarriers but also can provide an effective delivery carrier for growth factors.…”

Lasing‐Encoded Microsensor Driven by Interfacial Cavity Resonance Energy Transfer

“…Following incubation, the LC microdroplets were washed by adding PBS solution and performing centrifugation. Regarding the dye‐coating process, 1 mL of RhB/PBS solution with a 50 × 10 −6 m concentration was added to LC microdroplets before it was subjected to slowly mixing for a period of 1 h. Finally, the microdroplets were washed with PBS solution three times to remove the unbound dye in the surrounding medium . As a result, only those dye molecules that are coated on the microdroplet surface and form a monolayer of dye molecules.…”

Poly(α-l-lysine)-based nanomaterials for versatile biomedical applications: Current advances and perspectives

“…Reproduced with permission from Ref. [ 264 ], copyright 2017, American Chemical Society. (D) Construction of distinct maleimide density of PLL-OEG-Mal polymers immobilized on substrates for sensitive detection of cDNA.…”

“…Polymer-stabilized LC droplets in aqueous solutions have been developed as a simple and label-free optical probe for the detection of chemical and biological species. Recently, Pal's group explored the use of PLL-coated LC droplets for the bio-sensing of the cell, DNA, and anionic proteins such as fibronectin, bovine serum albumin, concanavalin A and cathepsin D, based on the transition in the LC director induced by interfacial intermolecular interactions between PLL and the anionic biomolecules [ 264 , [273] , [274] , [275] ]. The LC droplets were formed from 4-cyano-4′-pentylbiphenyl (5CB) and coated with alternative cationic PLL and anionic poly (styrene sulfonate) via the LbL technique.…”