Functionalization of liposomes: microscopical methods for preformulative screening

Abstract

The development of smart delivery systems able to deliver and target a drug to the site of action is one of the major challenges in the field of pharmaceutical technology. The surface modification of nanocarriers, such as liposomes, is widely investigated either for increasing the blood circulation time (by pegylation) or for interacting with specific tissues or cells (by conjugation of a selective ligand as a monoclonal antibody, mAb). Microscopical analysis thereby is a useful approach to evaluate the morphology and the size owing to resolution and versatility in defining either surface modification or the architecture and the internal structure of liposomes. This contribution aims to connect the outputs obtained by transmission electron (TEM) and atomic force (AFM) microscopical techniques for identifying the modifications on the liposomal surface. To reach this objective, we prepared liposomes applying two different pegylation technologies and further modifying the surface by mAb conjugation. This work demonstrates the feasibility to apply the combined approach (TEM and AFM analysis) in the evaluation of the efficacy of a surface engineering process.

Nanosystems based on siRNA silencing HuR expression counteract diabetic retinopathy in rat

“…STEM images (Fig. 1) well identified the architecture of liposomes (Lipo-A), featured by a homogeneous contrast in which the double layer was well detectable with a decreased electron transparency in comparison with the core area, as described in a previous report [20]. Besides, liposomes seem to aggregate forming more complicated structures in which the siRNA is not detectable.…”

Features of electron-microscopic visualization of soft phospholipid nanoparicles

“…Keywords: electron microscopy, negative staining, soft nanoparticles, phospholipids Введение Липиды в водном окружении способны формировать разнообразные наноструктуры: сферические и цилиндрические мицеллы, планарные ламеллярные структуры (бислои) и замкнутые (липосомы), инвертированную гексагональную фазу [1,2]. Это свойство липидов находит широкое применение в биотехнологии и медицине, в частности, наночастицы на ос-нове липидов используют в качестве носителя лекарственных препаратов [3][4][5]. Рациональный дизайн и синтез систем доставки препаратов на основе липидов требует контроля их структур-ной организации на протяжении всего процесса их сборки.…”

“…Метод негативного контрастирования был разработан для электронно-микроскопического исследования суспензий вирусных частиц, в дальнейшем он стал основным методом визу-ализации наноструктур различной природы, в том числе липидных [4,6]. Целью данной работы являлось изучение особенностей элек-тронно-микроскопической визуализации мягких наночастиц, на основе смесей (1) диолеилфосфа-тидилэтаноламина (DOPE) и фосфатидиловой кислоты (PA), и (2) фосфатидилхолина (PC) и холестерина с помощью различных контра-стирующих веществ.…”

Surface Modified Multifunctional and Stimuli Responsive Nanoparticles for Drug Targeting: Current Status and Uses

“…As with the aforementioned NCs, liposomes have been functionalized over time in order to achieve desirable properties, like stability, cell penetration, and so on [ 200 , 201 , 202 , 203 ]. PEGylated liposomes as promising particles to achieve long-circulating or as effective drug carriers have been widely synthesized [ 204 , 205 , 206 , 207 ].…”