ABSTRACT
Indocyanine green (ICG) is the only FDA-approved near-infrared dye and it is currently used clinically for diagnostic applications. However, there is significant interest in using ICG for triggered drug delivery applications and heat ablation therapy. Unfortunately, free ICG has a short half-life in vivo and is rapidly cleared from circulation. Liposomes have been frequently used to improve ICG's stability and overall time of effectiveness in vivo, but they have limited stability due to the susceptibility of phospholipids to hydrolysis and oxidation. In this study, nonphospholipid liposomes were used to encapsulate ICG, and the resulting liposomes were characterized for size, encapsulation efficiency, stability, and photothermal response. Using the thin-film hydration method, an ICG encapsulation efficiency of 54% was achieved, and the liposomes were stable for up to 12 weeks, with detectable levels of encapsulated ICG up to week 4. Additionally, ICG-loaded liposomes were capable of rapidly producing a significant photothermal response upon exposure to near-infrared light, and this photothermal response was able to induce changes in the mechanical properties of thermally responsive hydrogels. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1384-1392, 2019.
Subject(s)
Cholesterol/chemistry , Hyperthermia, Induced , Indocyanine Green/chemistry , Palmitic Acid/chemistry , Phototherapy , LiposomesABSTRACT
The use of optogenetics to activate or inhibit neurons is an important toolbox for neuroscientists. Several optogenetic devices are in use. These range from wired systems where the optoprobe is physically connected to the light source by a tether, to wireless systems that are remotely controlled. There are advantages and disadvantages of both; the wired systems are lightweight but limit movement due to the tether, and wireless systems allow unrestricted movement but may be heavier than wired systems. Both systems can be expensive to install and use. We have developed a low cost, wireless optogenetic probe, CerebraLux, built from off-the-shelf components. CerebraLux consists of two separable units; an optical component consisting of the baseplate holding the fiber-optic in place and an electronic component consisting of a light-emitting diode, custom-printed circuit board, an infrared receiver, microcontroller, and a rechargeable, lightweight lithium polymer battery. The optical component (0.5 g) is mounted on the head permanently, whereas the electronic component (2.3 g) is removable and is applied for each experiment. We describe the device, provide all designs and specifications, the methods to manufacture and use the device in vivo, and demonstrate feasibility in a mouse behavioral paradigm.
ABSTRACT
The need for temporal-spatial control over the release of biologically active molecules has motivated efforts to engineer novel drug delivery-on-demand strategies actuated via light irradiation. Many systems, however, have been limited to in vitro proof-of-concept due to biocompatibility issues with the photo-responsive moieties or the light wavelength, intensity, and duration. To overcome these limitations, this paper describes a light actuated drug delivery-on-demand strategy that uses visible and near-infrared (NIR) light and biocompatible chromophores: cardiogreen, methylene blue, and riboflavin. All three chromophores are capable of significant photothermal reaction upon exposure to NIR and visible light, and the amount of temperature change is dependent upon light intensity, wavelength as well as chromophore concentration. Pulsatile release of bovine serum albumin (BSA) from thermally responsive hydrogels was achieved over 4 days. These findings have the potential to translate light-actuated drug delivery-on-demand systems from the bench to clinical applications that require explicit control over the presentation of biologically active molecules.
