Alkylation of Spiropyran Moiety Provides Reversible Photo-Control over Nanostructured Soft Materials

Abstract

The purpose of this study was to create a light responsive nanostructured liquid crystalline matrix using a novel alkylated spiropyran photochromic molecule (spiropyran laurate, SPL) as a light activated drug delivery system. The liquid crystal matrix, prepared from phytantriol, responds reversibly to changes in photoisomerism of SPL on irradiation, switching between the bicontinuous cubic and the reversed hexagonal liquid crystal structures, a change previously shown to dramatically alter drug release rate. In contrast, the non-derivatized spiropyran and spirooxazine photochromic compounds do not sufficiently disrupt the matrix on isomerization to induce the phase change. Thus, novel alkylated spiropyran has the potential to be an effective agent for use in liquid crystalline systems for reversible ‘on-demand’ drug delivery applications.

Synthesis of Water-Soluble Spiropyran-Modified Poly(acrylic acid) Micelles and Their Optical Behaviors

“…In particular, a strong absorption peak appears at 550 nm in a neutral condition while both in an acid and base they are very low. This corresponds to the ringopening isomerism of spiropyran to merocyanine (SP to MC) that generally occurs in a neutral condition [41,42]. The absorption at 400 nm, however, is absolutely different from that at 550 nm.…”

Factors affecting the structure of lyotropic liquid crystals and the correlation between structure and drug diffusion

“…Encapsulating photochromic molecules such as spiropyran (SP), spirooxazine (SOX) and spiropyran laurate (SPL) is another way to introduce phase transformation. 31,32 These photochromic molecules can bind strongly to lipid molecules. Upon exposure to UV irradiation, the lattice parameters of the systems undergo changes, indicating that the photochromic molecules can disrupt lipid packing.…”

“…21 Fd3m has been of increasing interest to researchers because the release of hydrophilic substances from the reversed micellar cubic phase is slower than that from the reversed hexagonal phase. 22 The structures of the LLCs are affected by many factors including temperature, 19 pH, [23][24][25][26] light, [27][28][29][30][31][32] magnetic eld, 33,34 the type of amphiphilic, 35 water content 36,37 and additives. 38,39 Therefore, by altering the preparation conditions, desired phase structures can be achieved and intelligent carriers can be fabricated.…”

Understanding the photothermal heating effect in non-lamellar liquid crystalline systems, and the design of new mixed lipid systems for photothermal on-demand drug delivery

“…20 On addition of moderate amounts of DOPC (B20-40 mol%), V 2 was the predominant phase formed and the L 2 phase was no longer observed. 20 On addition of moderate amounts of DOPC (B20-40 mol%), V 2 was the predominant phase formed and the L 2 phase was no longer observed.…”

“…12 These transitions all involve manipulation of lipid self-assembly by altering lipid packing geometry 13 which can be reversibly achieved through environmental changes, amongst other variables. 16,17 Liquid crystalline nanostructure can be manipulated through a change in temperature in order to control release 14 and the ability to manipulate phase transitions via light activation, [18][19][20] as well as a change in pH has been shown. 14 Functionalised nanostructured materials, like self-assembled liquid crystalline matrices, are of particular interest for many bioapplications including the optimisation of pharmaceutical and diagnostic therapies.…”