China 
Africa 
Explore chapters and articles related to this topic
Dendrimers as a Candidate for Microbicide in Prevention of HIV-1 Infection in Women: Steps toward Their Clinical Evaluation
Published in Costas Demetzos, Stergios Pispas, Natassa Pippa, Drug Delivery Nanosystems, 2019
Daniel Sepúlveda-Crespo, Jose Luis Jiménez-Fuentes, María Angeles Muñoz-Fernández
For a quick screening of the different dendrimers, infection assays could be conducted in the TZM.bl cell line. Following this, infection assays in human epithelial cell lines would be performed. Pretreating the cells before the infection to study the preventive activity of the compounds could determine whether the compounds could be used as potential microbicides [12, 31, 95]. To study whether the compounds are involved during HIV-1 attachment or entry steps, peripheral blood mononuclear cells (PBMCs) will be treated in the presence of the compounds and then infected at 4°C, a temperature that does not allow Env-induced membrane fusion, thus arresting the virus at the attachment step (attachment), or at 37°C, a permissive temperature for membrane fusion and consequently for viral entry (entry) [110].
Graphene-Based Optical Biosensors and Imaging
Published in Li Jun, Wu Nianqiang, Biosensors Based on Nanomaterials and Nanodevices, 2017
Tang Zhiwen, He Shijiang, Pei Hao, Du Dan, Fan Chunhai, Lin Yuehe
Lu et al. have successfully employed GO and the pyrene-labeled peptide to construct a fluorescence nanobiosensor to study the interactions between peptide and protein,24 which play critical roles in many biological processes. In this study, the researchers have used human immunodeficiency virus type 1 (HIV-1) glycoprotein gp120, an important protein that is involved in the receptor binding and membrane fusion as the model. The authors have assembled the pyrene-labeled V3 region peptide in the gp120 protein on the GO surface by strong adsorption via π-π stacking and hydrophobic interactions. The fluorescence of the pyrene conjugated with peptide is effectively quenched as the result of the proximity of the GO to the pyrene moiety. In the presence of anti-HIV1-gp120 antibody, the competitive binding of the antibody with GO for peptide alters the conformation of the pyrene–peptide conjugate. As a result, the pyrene moiety is moved away from the GO surface. As a result, its fluorescence signal is consequently restored. This biosensor can specifically detect the interaction between the V3 region peptide and the anti-HIV1-gp120 antibody with a detection limit of 200 pM. This design presents a universal GO-based platform to specifically and sensitively monitor the peptide–protein interactions in a homogeneous real-time manner, which is important for investigating biomolecular recognition, drug development, and biosensor fabrications.
Aptamers as Tools for Targeted Drug Delivery
Published in Rakesh N. Veedu, Aptamers, 2017
Two RNA aptamers, D-12 and D-26, which target the hemagglutinin protein of influenza virus, were selected to test the therapeutic activity against influenza [34]. In influenza virus, the hemagglutinin protein mediates the initial steps in viral infection–receptor (glycan) binding and membrane fusion for cell entry. Both the aptamers were found to interfere with hemagglutinin–glycan interaction. The D-26 aptamer showed higher efficiency in distinguishing viral strains, and the affinity was further improved by incorporating the aptamer with 2′-fluoropyrimidines [34]. Oncolytic viruses are tumor-selective viruses that can destroy cancer cells by oncolysis. But quick clearance from the bloodstream and the acquired immunity to repeated infections by neutralizing antibodies (nAbs) restricts the use of oncolytic viruses in therapeutic applications. In a novel and versatile approach called aptamer-facilitated virus protection (AptaVIP), two types of aptamers were raised by the modified SELEX method to increase the in vivo oncolytic viral survival as a mode of anticancer treatment [57]. DNA aptamers were selected against vesicular stomatitis virus (oncolytic virus) and against the antigen-binding fragment (Fab) of antivesicular stomatitis virus polyclonal antibodies for shielding and blocking purposes, respectively, and they were modified and bridged together to form tetrameric counterparts. The authors were successful in demonstrating the use of this dual-aptamer AptaVIP system to block the antiviral antibodies and shield the virus from antibody neutralization that resulted in 77% viral infectivity in plaque-forming assay [57].
Loss of thermotolerance in antibiotic-resistant Acinetobacter baumannii
Published in International Journal of Environmental Health Research, 2021
Svjetlana Dekić Rozman, Ana Butorac, Rea Bertoša, Jasna Hrenović, Marina Markeš
The genome of A. baumannii codes for a variety of efflux pumps that actively remove antibiotics from the cell. The most significant are those pumps belonging to the resistance-nodulation-cell division (RND) superfamily of transporters. Three systems belonging to this superfamily have been identified thus far and associated with antibiotic resistance (AdeABC, AdeFGH, and AdeIJK) (Coyne et al. 2011; Li et al. 2015; Leus et al. 2018). The three-component structure enables the connection of the inner and outer membrane and works synergistically with the low permeability of the outer membrane (Leus et al. 2018). The structure of the efflux pumps is made of a membrane fusion protein (AdeA, AdeF, AdeI), protein transporters (AdeB, AdeG, AdeJ) and outer membrane factors (AdeC, AdeG, AdeK). The outer membrane factors provide the channel for the substances to cross the outer membrane and the membrane fusion proteins provide interactions between transporters and outer membrane factors (Leus et al. 2018). The efflux pumps AdeABC and AdeIJK have a broad substrate specificity including β-lactams. The downregulation of AdeA/AdeI family multidrug efflux protein expressed from adeI gene (UniProt Database, 2020), at elevated temperature suggests the decreased activity of efflux pumps especially the membrane fusion proteins that are responsible for the coupling of reactions separated in two different membranes (Leus et al. 2018).
Lipid-based liquid crystalline films and solutions for the delivery of cargo to cells
Published in Liquid Crystals Reviews, 2019
Marilyn Porras-Gomez, Cecilia Leal
Internalisation of materials in the cytosol requires overcoming at least two biological barriers: (1) crossing the semi-permeable cell membrane, and (2) escaping the endosome in a timely manner before the endosome-lysosome degradation pathway [35]. Membrane fusion and plasma membrane permeation are two different processes that both cost energy. Membrane fusion refers to the event of two different lipid bilayers merging into a single continuous bilayer. Membrane crossing depends on membrane permeability and physicochemical characteristics of the crossing molecules and it can occur via passive and active diffusion and/or membrane fusion, among others. It is noteworthy that membrane fusion is a well-established mechanism to mediate intracellular trafficking of molecules [36–38]. While membrane-fusion events are frequent in nature (e.g. during exocytosis, synaptic junctions, and endocytosis), crossing the plasma membrane is a much more selective process. Plasma membranes act as specific barriers against certain species such as ions [39,40], requiring protein ion pumps and carriers for instance. The majority of nanoparticles cross the plasma membrane via endocytosis. Unfortunately, the fate of most of these materials is often trapping and degradation inside the endosome. Endosomal escape is thus a crucial step that materials much overcome for efficient delivery of cargo to cells [41–43]. In this review article, we focus on a vastly unexplored physicochemical characteristic of drug carriers beyond composition, surface, size and shape: their internal nanostructure (Figure 2). In particular, we discuss the process of delivery of nucleic acids for gene silencing (siRNA) and hydrophobic small molecules (paclitaxel) using different lamellar and non-lamellar LLC films and particles. Lyotropic liquid crystals are promising materials to study the effects of structure on cell internalisation.