Fig 3 - uploaded by Martin Balouch
Content may be subject to copyright.
Volume size distribution (panel A) and TEM micrograph (panel B) of the prepared liposomes. The scale bar represents 1000 nm.
Source publication
Liposomal formulations can be advantageous in a number of scenarios such as targeted delivery to reduce the systemic toxicity of highly potent Active Pharmaceutical Ingredients (APIs), to increase drug bioavailability by prolonging systemic circulation, to protect labile APIs from degradation in the gastrointestinal tract, or to improve skin permea...
Contexts in source publication
Context 1
... Liposome properties. To validate our theoretical predictions, we have prepared dye-loaded liposomes as described in section 2.2. The prepared liposomes' size was centred at 800 nm irrespective of the loaded dye (Fig. 3A). However, a fraction of liposomes with a size around 100 nm was present in all samples and confirmed by TEM analysis (Fig. 3B). We suggest that the smaller liposomes (100 nm) do not settle during the centrifugation steps and are disposed of together with the supernatant during the purification process. This can be a possible source of ...
Context 2
... Liposome properties. To validate our theoretical predictions, we have prepared dye-loaded liposomes as described in section 2.2. The prepared liposomes' size was centred at 800 nm irrespective of the loaded dye (Fig. 3A). However, a fraction of liposomes with a size around 100 nm was present in all samples and confirmed by TEM analysis (Fig. 3B). We suggest that the smaller liposomes (100 nm) do not settle during the centrifugation steps and are disposed of together with the supernatant during the purification process. This can be a possible source of losses of the encapsulated substance and thus somewhat lower measured quantities of the released dye, as discussed ...
Citations
... The phenomena of API partitioning and permeability were investigated computationally and validated experimentally in our recent publication. 6 Systematic rules for the formulability of small-molecule APIs in liposomes have been proposed using the liposome biochemical classification system (LBCS). LBCS was designed as a two-dimensional (2D) diagram with approximative areas for the partitioning and permeation constants for each pair of API and lipid bilayer composition that enable or prevent successful liposome formulation. ...
... The lipid bilayer structure was obtained by molecular dynamics (MD) simulations, as described in detail in our recent work. 6 Briefly, a membrane bilayer containing 128 preordered lipid molecules was created by an in-house script. Slipids 27 parameters and the TIP3P 28 water model were used for the simulation, and the membrane was simulated at 293 K under periodic boundary conditions for approx. ...
Encapsulation into liposomes is a formulation strategy that can improve efficacy and reduce side effects of active pharmaceutical ingredients (APIs) that exhibit poor biodistribution or pharmacokinetics when administered alone. However, many APIs are unsuitable for liposomal formulations intended for parenteral administration due to their inherent physicochemical properties─lipid bilayer permeability and water-lipid equilibrium partitioning coefficient. Too high permeability results in premature leakage from liposomes, while too low permeability means the API is not able to pass across biological barriers. There are several options for solving this issue: (i) change of the lipid bilayer composition, (ii) addition of a permeability enhancer, or (iii) modification of the chemical structure of the API to design a prodrug. The latter approach was taken in the present work, and the effect of small changes in the molecular structure of the API on its permeation rate across a lipidic bilayer was systematically explored utilizing computer simulations. An in silico methodology for prodrug design based on the COSMOperm approach has been proposed and applied to four APIs (abiraterone, cytarabine, 5-fluorouracil, and paliperidone). It is shown that the addition of aliphatic hydrocarbon chains via ester or amide bonds can render the molecule more lipophilic and increase its permeability by approximately 1 order of magnitude for each 2 carbon atoms added, while the formation of fructose adducts can provide a more hydrophilic character to the molecule and reduce its lipid partitioning. While partitioning was found to depend only on the size and type of the added group, permeability was found to depend also on the added group location. Overall, it has been shown that both permeability and lipid partitioning coefficient can be systematically shifted into the desired liposome formulability window by appropriate group contributions to the parental drug. This can significantly increase the portfolio of APIs for which liposome or lipid nanoparticle formulations become feasible.
Three-dimensional cell culture systems are increasingly used for biological and anticancer drug screening as they mimic the structure and microenvironment of tumors more closely than conventional two-dimensional cell models. In this study, the growth kinetics of colon adenocarcinoma-derived spheroids (HT-29 cell line) cultivated in liquid marble micro-bioreactors and nonadherent PDMS-coated well plates was investigated in detail and enabled precise control of the spheroid size by the seed cell density and cultivation time. The therapeutic effect of 5-fluorouracil and irinotecan hydrochloride in 2D monolayer cell culture and 3D tumor spheroids revealed an unexpected twist in their efficacy due to different ability to penetrate through 3D microtissue. For 5-fluorouracil, the inhibitory concentration IC50 after 48 h exposure increased from 11.3 µM for a 2D cell culture to 707.7 µM for a 3D spheroid. In the case of irinotecan, IC50 increased from 24.9 µM to 77.8 µM. Despite its higher molar weight, irinotecan appeared to penetrate the 3D spheroid structure more efficiently than 5-fluorouracil. While 5-fluorouracil mainly caused a suppression of spheroid growth from the outside, irinotecan affected the entire spheroid and caused its originally compact structure to disintegrate. The acquired results highlight the need to screen cancer chemotherapeutics on 3D tumor models, as contrasting results can be obtained compared to standard 2D cell cultures.
Pharmaceutical nanocrystals represent a promising new formulation that combines the benefits of bulk crystalline materials and colloidal nanoparticles. To be applied in vivo, nanocrystals must meet several criteria, namely colloidal stability in physiological media, non-toxicity to healthy cells, avoidance of macrophage clearance, and bioactivity in the target tissue. In the present work curcumin, a naturally occurring poorly water-soluble molecule with a broad spectrum of bioactivity has been considered as a candidate substance for preparing pharmaceutical nanocrystals. Curcumin nanocrystals in the size range of 40-90 nm were prepared by wet milling using the following combination of steric and ionic stabilizers: Tween 80, sodium dodecyl sulfate, Poloxamer 188, hydroxypropyl methylcellulose, phospholipids (with and without polyethylene glycol), and their combination. Nanocrystals stabilized by a combination of phospholipids enriched with polyethylene glycol proved to be the most successful in all evaluated criteria; they were colloidally stable in all media, exhibited low macrophage clearance, and proved non-toxic to healthy cells. This curcumin nanoformulation also exhibited outstanding anticancer potential comparable to commercially used cytostatics (IC50=73 µM; 24 h, HT-29 colorectal carcinoma cell line) which represents an improvement of several orders of magnitude when compared to previously studied curcumin formulations. This work shows that the preparation of phospholipid-stabilized nanocrystals allows for the conversion of poorly soluble compounds into a highly effective “solution-like” drug delivery system at pharmaceutically relevant drug concentrations.
Fully acetylated deoxyfluorinated hexosamine analogues and non-fluorinated 3,4,6-tri-O-acylated N-acetyl-hexosamine hemiacetals have previously been shown to display moderate anti-proliferative activity. We prepared a set of deoxyfluorinated GlcNAc and GalNAc hemiacetals that comprised both features: O-acylation at the non-anomeric positions with an acetyl, propionyl and butanoyl group, and deoxyfluorination at selected positions. Determination of the in vitro cytotoxicity towards the MDA-MB-231 breast cancer and HEK-293 cell lines showed that deoxyfluorination enhanced cytotoxicity in most analogues. Increasing the ester alkyl chain length had a variable effect on the cytotoxicity of fluoro analogues, which contrasted with non-fluorinated hemiacetals where butanoyl derivatives had always higher cytotoxicity than acetates. Reaction with 2-phenylethanethiol indicated that the recently described S-glyco-modification is an unlikely cause of cytotoxicity.
