Internalization mechanisms of cell-penetrating peptides

• Ivana Ruseska and
• Andreas Zimmer

Beilstein J. Nanotechnol. 2020, 11, 101–123, doi:10.3762/bjnano.11.10

• the cell interior. Nevertheless, the mechanism they use to enter cells still remains an unsolved piece of the puzzle. Endocytosis and direct penetration have been suggested as the two major mechanisms used for internalization, however, it is not all black and white in the nanoworld. Studies have shown

• that several CPPs are able to induce and shift between different uptake mechanisms depending on their concentration, cargo or the cell line used. This review will focus on the major internalization pathways CPPs exploit, their characteristics and regulation, as well as some of the factors that

• influence the cellular uptake mechanism. Keywords: cell-penetrating peptides; direct translocation; drug delivery; endocytosis; internalization; Introduction The cell membrane is a semipermeable barrier, serving as a protective layer for the cells. It is an essential organelle for cell survival and

The different ways to chitosan/hyaluronic acid nanoparticles: templated vs direct complexation. Influence of particle preparation on morphology, cell uptake and silencing efficiency

• Arianna Gennari,
• Julio M. Rios de la Rosa,
• Erwin Hohn,
• Maria Pelliccia,
• Enrique Lallana,
• Roberto Donno,
• Annalisa Tirella and
• Nicola Tirelli

Beilstein J. Nanotechnol. 2019, 10, 2594–2608, doi:10.3762/bjnano.10.250

• protein adsorption on chitosan-containing nanoparticles [14] and a receptor-mediated mechanism of internalization [15]. A larger size of the anionic component corresponds to a higher avidity toward chitosan, thus polyelectrolyte complexes are more stable but also difficult to reverse; this irreversibility

• presentation of HA [18], which affected the nanoparticle internalization in both RAW 264.7 macrophages [19][20] and XS106 dendritic cells [21]. In both cases, nanoparticles based on chitosan of low molecular weight appeared to be surrounded by a corona of loosely bound HA, which on one hand lowered the maximum

• -116 cells massively express CD44, both in its standard and variant forms [42]. Their “HA receptor cocktail” may trigger internalization processes with conditions that favour the endosomolytic properties of high-MW chitosan. High-MW polycations should, in principle, be better at membrane disruption

Small protein sequences can induce cellular uptake of complex nanohybrids

• Jan-Philip Merkl,
• Malak Safi,
• Christian Schmidtke,
• Fadi Aldeek,
• Johannes Ostermann,
• Tatiana Domitrovic,
• Sebastian Gärtner,
• John E. Johnson,
• Horst Weller and
• Hedi Mattoussi

Beilstein J. Nanotechnol. 2019, 10, 2477–2482, doi:10.3762/bjnano.10.238

• [20][21]. This peptide is produced during viral capsid maturation and is thought to enable cellular internalization of the virus. It has been shown that the MBP-fused γ-peptide is able to disrupt artificial liposomes [20][21]. Recently, we have used this His6-MBP-γ to promote the uptake of QDs by

Toxicity and safety study of silver and gold nanoparticles functionalized with cysteine and glutathione

• Barbara Pem,
• Igor M. Pongrac,
• Lea Ulm,
• Ivan Pavičić,
• Valerije Vrček,
• Darija Domazet Jurašin,
• Marija Ljubojević,
• Adela Krivohlavek and
• Ivana Vinković Vrček

Beilstein J. Nanotechnol. 2019, 10, 1802–1817, doi:10.3762/bjnano.10.175

• concentration of 25 mg Ag L−1 would release only 0.2 mg Ag+ L−1 in the cell culture media, the concentration of ionic Ag that is non-toxic to L929 cells. Thus, the toxicity mechanism is much more complicated than a simple metal ion release in cell culture media. The cellular internalization of NPs by active

• Figure S7 in Supporting Information File 1). This is in accordance with recently published in vivo data on GSH-coated gold nanoclusters with promising theranostic properties [55][56]. Our GSH-AuNPs bypassed internalization by L929 cells similar to the interaction of GSH-protected Au nanoclusters with the

• with regard to cell viability, the number of cells in late apoptosis, and DNA damage, which can be explained by efficient internalization of these type of AuNPs (Figure 5, Figures S6 and S7 in Supporting Information File 1). The GSH-AuNPs proved to be not only less toxic than CYS-AuNPs, but even

Scavenging of reactive oxygen species by phenolic compound-modified maghemite nanoparticles

• Małgorzata Świętek,
• Yi-Chin Lu,
• Rafał Konefał,
• Liliana P. Ferreira,
• M. Margarida Cruz,
• Yunn-Hwa Ma and
• Daniel Horák

Beilstein J. Nanotechnol. 2019, 10, 1073–1088, doi:10.3762/bjnano.10.108

• augment particle internalization compared to heparin modification alone. Previous studies have suggested that electrostatic interactions, oxidation-dependent conjugation, and hydrogen bonds between the phenolic OH groups and polysaccharide moieties and/or amino acid residues of the cell membrane may

• enhance nanoparticle internalization [34]. The application of a magnetic field during incubation with γ-Fe2O3 increased the MNPcell level by 2.7-fold compared with that without the magnet in L-929 cells. The γ-Fe2O3@Hep uptake in LN-229 cells was increased by 1.8-fold compared with that without magnetic

• phenolic compound-modified nanoparticles (100 μg/mL), they were incubated with L-929 and LN-229 cells for 3 h, and 2 mM H2O2 was added for 30 min, followed by staining with CM-H2DCFDA for 1 h. Figure 6 shows the representative flow cytometry results of nanoparticle internalization and the intracellular ROS

Serum type and concentration both affect the protein-corona composition of PLGA nanoparticles

• Katrin Partikel,
• Robin Korte,
• Dennis Mulac,
• Hans-Ulrich Humpf and
• Klaus Langer

Beilstein J. Nanotechnol. 2019, 10, 1002–1015, doi:10.3762/bjnano.10.101

• enrichment in the membrane. This step is usually considered as a prerequisite for a successive internalization by cells [38]. Besides, some of the proteins in the corona could mediate the interaction with cells by the recognition of specific receptor binding sites localized on the cell surface and thus

Heating ability of magnetic nanoparticles with cubic and combined anisotropy

• Nikolai A. Usov,
• Mikhail S. Nesmeyanov,
• Elizaveta M. Gubanova and
• Natalia B. Epshtein

Beilstein J. Nanotechnol. 2019, 10, 305–314, doi:10.3762/bjnano.10.29

• SAR in the alternating magnetic field [3][16]. On the contrary, in biological media, nanoparticles have a tendency to aggregate because of active biological processes, such as cellular internalization in endocytic compartments [10][13]. As a result, the nanoparticles in biological media may form

Targeting strategies for improving the efficacy of nanomedicine in oncology

• Gonzalo Villaverde and
• Alejandro Baeza

Beilstein J. Nanotechnol. 2019, 10, 168–181, doi:10.3762/bjnano.10.16

• selective delivery to these organelles [49]. The peptide Lys–Asp–Glu–Leu (KDEL) has been anchored on gold nanoparticles loaded with siRNA for the selective delivery of the genetic material into the endoplasmic reticulum [50]. The main mechanism for the internalization of nanoparticles within mammalian cells

• solutions, a real alternative? Active targeting is already one of the most used strategies for bringing nanoformulations into tumoral cells. Although usually great results were achieved in vitro, the in vivo assays have shown smaller effects regarding cell internalization. There has been no real enhancement

• and affinity to glioma cells for LPR interaction. The exposed dual peptide cation enables the possible accumulation into gliomas via the combination of EPR effect and active targeting for an antiangiogenic and apoptotic treatment. In vitro assays showed improved internalization only when the liposomes

The nanoscaled metal-organic framework ICR-2 as a carrier of porphyrins for photodynamic therapy

• Jan Hynek,
• Sebastian Jurík,
• Martina Koncošová,
• Jaroslav Zelenka,
• Ivana Křížová,
• Tomáš Ruml,
• Kaplan Kirakci,
• Ivo Jakubec,
• František Kovanda,
• Kamil Lang and
• Jan Demel

Beilstein J. Nanotechnol. 2018, 9, 2960–2967, doi:10.3762/bjnano.9.275

• rate of internalization of the photosensitizers into the cells with different modifications of nanoICR-2. The highest cellular uptake was observed for nanoICR-2/TPPPi(Ph), followed by nanoICR-2/TPPPi(iPr) and nanoICR-2/TPPPi(Me). The most efficiently accumulating sample nanoICR-2/TPPPi(Ph) was

Cytotoxicity of doxorubicin-conjugated poly[N-(2-hydroxypropyl)methacrylamide]-modified γ-Fe₂O₃ nanoparticles towards human tumor cells

• Zdeněk Plichta,
• Yulia Kozak,
• Rostyslav Panchuk,
• Viktoria Sokolova,
• Matthias Epple,
• Lesya Kobylinska,
• Pavla Jendelová and
• Daniel Horák

Beilstein J. Nanotechnol. 2018, 9, 2533–2545, doi:10.3762/bjnano.9.236

• stability in aqueous media and limited internalization by the cells, however, enabled adhesion to the cell surface. While the neat PHPMA-coated particles proved to be non-toxic, doxorubicin-conjugated particles exhibited enhanced cytotoxicity in both drug-sensitive and drug-resistant tumor cells compared to

• , internalization of PHPMA-modified γ-Fe2O3 particles by the cells was restricted and the particles were localized mostly on the cell surface and in the perimembranous space, where Dox retained its activity. To get comparable dose-dependent data, the amount of Dox in P(HPMA-MMAA)-Dox added to the γ-Fe2O3@PHPMA

Involvement of two uptake mechanisms of gold and iron oxide nanoparticles in a co-exposure scenario using mouse macrophages

• Dimitri Vanhecke,
• Dagmar A. Kuhn,
• Dorleta Jimenez de Aberasturi,
• Sandor Balog,
• Ana Milosevic,
• Dominic Urban,
• Diana Peckys,
• Niels de Jonge,
• Wolfgang J. Parak,
• Alke Petri-Fink and
• Barbara Rothen-Rutishauser

Beilstein J. Nanotechnol. 2017, 8, 2396–2409, doi:10.3762/bjnano.8.239

• single-exposure experiment. This may initially appear paradoxical can be easily explained by the activation of two parallel uptake pathways. After internalization, the fluorescent signals from AuNPs and FeOxNPs never completely colocalise, which may again be a reflection of different uptake mechanisms

• [39]. Furthermore, it was shown that exosomes moved along the extracellular side of filopodia prior to internalization [40]. The transport along filopodia has been suggested to be mediated by the underlying actin–myosin cytoskeleton [41]. The distance between linearly arranged AuNPs averaged 37 nm

Carbon nano-onions as fluorescent on/off modulated nanoprobes for diagnostics

• Stefania Lettieri,
• Marta d’Amora,
• Adalberto Camisasca,
• Alberto Diaspro and
• Silvia Giordani

Beilstein J. Nanotechnol. 2017, 8, 1878–1888, doi:10.3762/bjnano.8.188

• development of a nanosensor which can be “turned on” in an acidic environment. Remarkably, the fluo-CNOs maintained the switching properties upon cell internalization, as they were “switched-on” in response to acidic pH. In vitro experiments on HeLa cells showed excellent cellular uptake and low toxicity of

• application as intracellular sensors. Confocal imaging Confocal imaging was performed on human cervical carcinoma (HeLa) cells treated with fluo-CNOs, in order to confirm the preservation of the PET and ICT characteristics of the dye attached to CNOs after cell internalization, hence the possible use of fluo

Synthesis and functionalization of NaGdF₄:Yb,Er@NaGdF₄ core–shell nanoparticles for possible application as multimodal contrast agents

• Dovile Baziulyte-Paulaviciene,
• Vitalijus Karabanovas,
• Marius Stasys,
• Greta Jarockyte,
• Vilius Poderys,
• Simas Sakirzanovas and
• Ricardas Rotomskis

Beilstein J. Nanotechnol. 2017, 8, 1815–1824, doi:10.3762/bjnano.8.183

• , Tween 80-coated core–shell nanoparticles presented enhanced optical and MR signal intensity, good colloidal stability, low cytotoxicity and nonspecific internalization into two different breast cancer cell lines, which indicates that these nanoparticles could be applied as an efficient, dual-modal

Uptake and intracellular accumulation of diamond nanoparticles – a metabolic and cytotoxic study

• Antonín Brož,
• Lucie Bačáková,
• Pavla Štenclová,
• Alexander Kromka and
• Štěpán Potocký

Beilstein J. Nanotechnol. 2017, 8, 1649–1657, doi:10.3762/bjnano.8.165

• in cultures exposed and unexposed to photoluminescent nanodiamonds. This positive effect can be attributed to the fact that the mechanism of the ND uptake was clathrin-mediated endocytosis, that is, a physiological cellular mechanism for internalization of various bioactive substances from the

Cationic PEGylated polycaprolactone nanoparticles carrying post-operation docetaxel for glioma treatment

• Cem Varan and
• Erem Bilensoy

Beilstein J. Nanotechnol. 2017, 8, 1446–1456, doi:10.3762/bjnano.8.144

• than 100 nm and a net positive surface charge to facilitate cellular internalization of drug-loaded nanoparticles. Hydroxypropyl cellulose films were prepared to incorporate these nanoparticle dispersions to complete the implantable drug delivery system. Results: The diameter of core–shell

• effective on growth inhibition of breast and prostate cancer cells when compared to free docetaxel [23]. Core–shell nanoparticles are also used as non-viral vectors for the treatment of glioma. Zamora et al. prepared photochemical internalization mediated polyamine core–shell nanoparticles for tumor

Nano-engineered skin mesenchymal stem cells: potential vehicles for tumour-targeted quantum-dot delivery

• Liga Saulite,
• Dominyka Dapkute,
• Karlis Pleiko,
• Ineta Popena,
• Simona Steponkiene,
• Ricardas Rotomskis and
• Una Riekstina

Beilstein J. Nanotechnol. 2017, 8, 1218–1230, doi:10.3762/bjnano.8.123

• QDs possessing a protein corona are differently recognized by NIH3T3 cells and internalized by different pathways [23], consistent with the data from the present study. Interestingly, MSCs showed more effective internalization of QDs under serum-free conditions, as the protein corona interferes with

• observed internalization of QDs in early endosomes after 6 h of incubation, followed by re-localization to late endosomes/lysosomes after 24 and 48 h of incubation (Figure 8). Cell division, excretion and degradation are the main mechanisms reported for QD signal elimination over time [50][51]. It has been

Uptake of the proteins HTRA1 and HTRA2 by cells mediated by calcium phosphate nanoparticles

• Olga Rotan,
• Katharina N. Severin,
• Simon Pöpsel,
• Alexander Peetsch,
• Melisa Merdanovic,
• Michael Ehrmann and
• Matthias Epple

Beilstein J. Nanotechnol. 2017, 8, 381–393, doi:10.3762/bjnano.8.40

• that the main internalization pathway for anionic calcium phosphate nanoparticles into HeLa cells was macropinocytosis. In that case, cationic nanoparticles were also taken up much better than anionic nanoparticles [47]. This is also supported by earlier studies on the uptake of nanoparticles with

Viability and proliferation of endothelial cells upon exposure to GaN nanoparticles

• Tudor Braniste,
• Ion Tiginyanu,
• Tibor Horvath,
• Simion Raevschi,
• Serghei Cebotari,
• Marco Lux,
• Axel Haverich and
• Andres Hilfiker

Beilstein J. Nanotechnol. 2016, 7, 1330–1337, doi:10.3762/bjnano.7.124

• . Since each cell division reduces the number of the incorporated GaN nanoparticles by 50%, the load of GaN nanoparticles in a single cell diminishes with time. The growth of endothelial cells on top of fixed nanoparticles avoids the internalization process of nanoparticles by cells. Surface

On the pathway of cellular uptake: new insight into the interaction between the cell membrane and very small nanoparticles

• Claudia Messerschmidt,
• Daniel Hofmann,
• Anja Kroeger,
• Katharina Landfester,
• Volker Mailänder and
• Ingo Lieberwirth

Beilstein J. Nanotechnol. 2016, 7, 1296–1311, doi:10.3762/bjnano.7.121

• diameter tested a different membrane morphology during uptake can be observed and that the amount of particles entering in one event is different for the three sizes. Silica particles with a diameter of 22 nm show single-particle internalization with a membrane wrapped around the particles in the cytosol

Improved biocompatibility and efficient labeling of neural stem cells with poly(L-lysine)-coated maghemite nanoparticles

• Igor M. Pongrac,
• Marina Dobrivojević,
• Lada Brkić Ahmed,
• Michal Babič,
• Miroslav Šlouf,
• Daniel Horák and
• Srećko Gajović

Beilstein J. Nanotechnol. 2016, 7, 926–936, doi:10.3762/bjnano.7.84

• their cellular uptake, the mechanism of internalization, cytotoxicity, viability and proliferation of neural stem cells, and compared them to the commercially available dextran-coated nanomag®-D-spio nanoparticles. Results: Light microscopy of Prussian blue staining revealed a concentration-dependent

• of neural stem cells. Cytochalasine D blocked the cellular uptake of nanoparticles indicating an actin-dependent process, such as macropinocytosis, to be the internalization mechanism for both nanoparticle types. Finally, immunocytochemistry analysis of neural stem cells after treatment with poly(L

• tracking [16]. Biocompatible polymers are used to modify the surface of nanoparticles, prevent their agglomeration and facilitate internalization. The most widely used coating for surface modification of nanoparticles is dextran, which promotes nanoparticle internalization, in particular in different

Silica-coated upconversion lanthanide nanoparticles: The effect of crystal design on morphology, structure and optical properties

• Uliana Kostiv,
• Miroslav Šlouf,
• Hana Macková,
• Alexander Zhigunov,
• Hana Engstová,
• Katarína Smolková,
• Petr Ježek and
• Daniel Horák

Beilstein J. Nanotechnol. 2015, 6, 2290–2299, doi:10.3762/bjnano.6.235

• in OM, serving as both solvent and surface binding ligand [20]. Because the particle size plays a key role in biomedical applications, e.g., for internalization of nanoparticles by cells of the reticuloendothelial system [32], the effects of both reaction temperature and time were investigated to

Natural and artificial binders of polyriboadenylic acid and their effect on RNA structure

• Giovanni N. Roviello,
• Domenica Musumeci,
• Valentina Roviello,
• Marina Pirtskhalava,
• Alexander Egoyan and
• Merab Mirtskhulava

Beilstein J. Nanotechnol. 2015, 6, 1338–1347, doi:10.3762/bjnano.6.138

• delivery of these molecular tools can be selectively directed towards cancer cells and, after their internalization, the anticancer activity could be exerted either by the entire conjugate or by the free binder after loss of the targeting agent. Thus, due to the importance of poly(rA) binders, for example

PLGA nanoparticles as a platform for vitamin D-based cancer therapy

• Maria J. Ramalho,
• Joana A. Loureiro,
• Bárbara Gomes,
• Manuela F. Frasco,
• Manuel A. N. Coelho and
• M. Carmo Pereira

Beilstein J. Nanotechnol. 2015, 6, 1306–1318, doi:10.3762/bjnano.6.135

• calcitriol remained stable at release conditions throughout the experiment period. Cellular uptake of PLGA NPs and calcitriol-induced morphological changes The internalization of fluorescent C6–calcitriol–PLGA NPs by S2-013, hTERT-HPNE and A549 cells was evaluated by confocal microscopy. Counterstaining of

• pancreatic cell lines, S2-013 and hTERT-HPNE, was reported. The in vitro proliferation assay showed that the encapsulation of calcitriol enhanced its antiproliferative activity. The efficient cell internalization by an endocytosis mechanism of PLGA NPs and their rapid endo-lysosomal escape observed in this

• , this mechanism of NP internalization avoids calcitriol transport out of cells mediated by P-glycoprotein involved in the MDR problem. It was previously established that after internalization, PLGA NPs suffer a charge change triggered by the acidic medium of late endosome/lysosome. This leads to the

Protein corona – from molecular adsorption to physiological complexity

• Lennart Treuel,
• Dominic Docter,
• Michael Maskos and
• Roland H. Stauber

Beilstein J. Nanotechnol. 2015, 6, 857–873, doi:10.3762/bjnano.6.88

• cellular uptake. A possible contribution to this observation is that, in presence of free proteins, the cellular endocytosis machinery was also occupied with internalization of the freely dissolved protein. However, intriguing differences were found between the effects of the different coronae, essentially

• all consisting of HSA with just minor chemical modifications as described above. Internalization of HSAam-coated NPs by the cells was completely suppressed within the sensitivity limits of their experiment. In addition the time-dependent NP uptake by HeLa cells was investigated, using spinning disk

• also determined for internalization of NPs and varied less than a factor of 2. The combined interpretation of their data, allowed them to deduce that the overall uptake is controlled by the binding of the NP to the cell membrane. These findings will clearly help to design NPs for directed cellular

Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

• Shanka Walia and
• Amitabha Acharya

Beilstein J. Nanotechnol. 2015, 6, 546–558, doi:10.3762/bjnano.6.57

• cancer cells were treated and monitored under a fluorescence microscope at 405 nm excitation. Intense green fluorescence was observed from cancer cells which confirmed the internalization of NPs. Similarly, Pinho et al. [15] reported the synthesis of a bimodal MRI probe by embedding two lanthanide metal

• internalized by RAW 264.7 cells. An increase in the intensity of T1-weighted MRI images of cellular pellets was observed when these nanocomposites were treated with the cells. The internalization into the cells was also monitored by fluorescence microscopy at 393 nm excitation. Recently, there has been a