Enhanced cellular uptake of folic acid-conjugated PLGA-PEG nanoparticles loaded with vincristine sulfate in human breast cancer

The aim of this paper is to evaluate the cellular uptake of vincristine sulfate-loaded poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles with the folic acid modification (PLGA-PEG-folate NPs). PLGA-PEG-folate NPs were prepared using a water-oil-water emulsion solvent evaporation method. The particle size, surface morphology, drug encapsulation efficiency, and the drug release behavior were investigated. The NPs exhibited a biphasic drug release with a moderate initial burst followed by a sustained release profile. Internalization of the NPs labeled with coumarin- 6 by MCF-7 (Michigan Cancer Foundation-7) human breast cancer cells was quantitatively measured by microplate reader, and qualitatively analyzed by fluorescent microscopy and confocal laser scanning microscopy. The results showed PLGA-PEG-folate NPs achieved significantly higher cellular uptake in the folic acid receptor overexpressed MCF-7 cells, compared to PLGA-mPEG NPs without the folic acid modification. Due to the enhanced cellular uptake, PLGA-PEG-folate NPs displayed the highest cytotoxicity. Judged by IC(50) after 24 h culture, the therapeutic effects of the drug formulated in the NPs with surface modification could be 1.52 times, 3.91 times higher than that of PLGA-mPEG NPs and free vincristine sulfate, respectively.     

Trastuzumab‐conjugated nanoparticles composed of poly(butylene adipate‐co ‐butylene terephthalate) prepared by electrospraying technique for targeted delivery of docetaxel

Human epidermal growth factor receptor 2 (HER‐2) is overexpressed in 20–30% of human breast cancers, associated with poor prognosis and tumour aggression. The aim of this study was the production of trastuzumab‐targeted Ecoflex nanoparticles (NPs) loaded with docetaxel and in vitro evaluation of their cytotoxicity and cellular uptake. The NPs were manufactured by electrospraying and characterised regarding size, zeta potential, drug loading, and release behaviour. Then their cytotoxicity was evaluated by MTT assay against an HER‐2‐positive cell line, BT‐474, and an HER‐2‐negative cell line, MDA‐MB‐468. The cellular uptake was studied by flow cytometry and fluorescent microscope. The particle size of NPs was in an appropriate range, with relatively high drug entrapment and acceptable release efficiency. The results showed no cytotoxicity for the polymer, but the significant increment of cytotoxicity was observed by treatment with docetaxel‐loaded NPs in both HER‐2‐positive and HER‐2‐negative cell lines, in comparison with the free drug. The trastuzumab‐targeted NPs also significantly enhanced cytotoxicity against BT‐474 cells, compared with non‐targeted NPs.Inspec keywords: cancer, proteins, biomedical materials, nanofabrication, drug delivery systems, cellular biophysics, biological organs, nanomedicine, toxicology, tumours, nanoparticles, biomedical optical imaging, fluorescence, particle sizeOther keywords: human breast cancers, tumour aggression, trastuzumab‐targeted Ecoflex nanoparticles, cellular uptake, zeta potential drug loading, HER‐2‐positive cell line, HER‐2‐negative cell line, MDA‐MB‐468, particle size, trastuzumab‐conjugated nanoparticles, electrospraying technique, human epidermal growth factor receptor, cytotoxicity, nontargeted nanoparticles, butylene adipate‐co‐butylene terephthalate, trastuzumab‐targeted NP, docetaxel‐loaded NP     

Enhanced cellular uptake of a glutathione selective fluorogenic probe encapsulated in nanoparticles

Selective fluorogenic probes for the labelling of intracellular reduced glutathione (GSH), i.e.?ortho-phthaldialdehyde (OPA) and naphthalene-2,3-dicarboxaldehyde (NDA), have been encapsulated in polymeric nanoparticles (NPs) and the ability of the NPs to enhance uptake of the probe by microbial cells has been evaluated. Preparation of the probe-loaded NPs composed of Eudragit(?) E was based on an oil-in-water emulsification solvent evaporation method using an ultrasonic probe and polyvinyl alcohol as the surfactant. The encapsulation efficiency of the probes in lyophilized NPs was determined using high performance liquid chromatography (HPLC). A higher encapsulation rate of NDA than OPA was found: 47.6 ± 9.9?(n = 6) and 2.1 ± 0.2%?(n = 3), respectively. The NDA-loaded particle diameter and zeta potential were 224.6 ± 14.7?nm and +40.9 ± 6.5?mV, respectively. After 20?min incubation of cultured Candida albicans yeast cells with either free NDA or NDA-loaded NPs (final NDA concentration 100?μM), cells were harvested and corresponding lysates were analysed using HPLC coupled with spectrofluorimetric detection. Incubation of cells with NDA-loaded NPs increased intracellular levels of NDA-GSH adduct by about nine-fold in comparison with the free probe. Adhesion on the cells and the penetration behaviour of NPs loaded with either NDA or fluorescent label (Nile Red) were characterized qualitatively by confocal laser scanning microscopy.     

Fluorescence‐Encoded Gold Nanoparticles: Library Design and Modulation of Cellular Uptake into Dendritic Cells

In order to harness the unique properties of nanoparticles for novel clinical applications and to modulate their uptake into specific immune cells we designed a new library of homo‐ and hetero‐functional fluorescence‐encoded gold nanoparticles (Au‐NPs) using different poly(vinyl alcohol) and poly(ethylene glycol)‐based polymers for particle coating and stabilization. The encoded particles were fully characterized by UV‐Vis and fluorescence spectroscopy, zeta potential and dynamic light scattering. The uptake by human monocyte derived dendritic cells in vitro was studied by confocal laser scanning microscopy and quantified by fluorescence‐activated cell sorting and inductively coupled plasma atomic emission spectroscopy. We show how the chemical modification of particle surfaces, for instance by attaching fluorescent dyes, can conceal fundamental particle properties and modulate cellular uptake. In order to mask the influence of fluorescent dyes on cellular uptake while still exploiting its fluorescence for detection, we have created hetero‐functionalized Au‐NPs, which again show typical particle dependent cellular interactions. Our study clearly prove that the thorough characterization of nanoparticles at each modification step in the engineering process is absolutely essential and that it can be necessary to make substantial adjustments of the particles in order to obtain reliable cellular uptake data, which truly reflects particle properties.     

Fluorescent Polymer Nanoparticles Based on Dyes: Seeking Brighter Tools for Bioimaging

Speed, resolution and sensitivity of today's fluorescence bioimaging can be drastically improved by fluorescent nanoparticles (NPs) that are many‐fold brighter than organic dyes and fluorescent proteins. While the field is currently dominated by inorganic NPs, notably quantum dots (QDs), fluorescent polymer NPs encapsulating large quantities of dyes (dye‐loaded NPs) have emerged recently as an attractive alternative. These new nanomaterials, inspired from the fields of polymeric drug delivery vehicles and advanced fluorophores, can combine superior brightness with biodegradability and low toxicity. Here, we describe the strategies for synthesis of dye‐loaded polymer NPs by emulsion polymerization and assembly of pre‐formed polymers. Superior brightness requires strong dye loading without aggregation‐caused quenching (ACQ). Only recently several strategies of dye design were proposed to overcome ACQ in polymer NPs: aggregation induced emission (AIE), dye modification with bulky side groups and use of bulky hydrophobic counterions. The resulting NPs now surpass the brightness of QDs by ≈10‐fold for a comparable size, and have started reaching the level of the brightest conjugated polymer NPs. Other properties, notably photostability, color, blinking, as well as particle size and surface chemistry are also systematically analyzed. Finally, major and emerging applications of dye‐loaded NPs for in vitro and in vivo imaging are reviewed.     

Intracellular delivery of etoposide loaded biodegradable nanoparticles: cytotoxicity and cellular uptake studies

The preferred delivery systems for anticancer drugs would be the one which would have selective and effective destruction of cancer cells. In the present study etoposide (ETO) loaded nanoparticles (NP) were prepared using PLGA (ETO-PLGA NP), PLGA-MPEG block copolymer (ETO-PLGA-MPEG NP) and PLGA-Pluronic copolymer (ETO-PLGA-PLU NP) and they were evaluated for cytotoxicity and cellular uptake studies using two cancer cell lines, L1210 and DU145. The IC50 values for L1210 cells were 18.0, 6.2, 4.8 and 5.4 microM and for DU145 cells the IC50 values were 98.4, 75.1, 60.1 and 71.3 microM for ETO, ETO-PLGA NP, ETO-PLGA-MPEG NP and ETO-PLGA-PLU NP respectively. The increased cytotoxicities were attributed to increased uptake of the NPs by the cells. Moreover the ETO loaded PLGA-MPEG NP and PLGA-Pluronic NP showed a sustained cytotoxic effect till 5 days on both the cell lines. Results of the long term cytotoxicity study concluded that the drug loaded PLGA nanoparticulate formulations were efficient in decreasing the viability of the L1210 cells over a period of three days, whereas the pure drug exerted its maximum efficiency on the day one itself. Z-stack confocal images of NPs showed fluorescence activity in each section of DU 145 and L1210 cells indicating that the nanoparticles were internalized by the cells. The study concluded that ETO loaded PLGA NPs had higher cytotoxicity compared with that of the free drug and ETO-PLGA-MPEG NP and ETO-PLGA-PLU NP had higher cell uptake efficiency compared with that of ETO-PLGA NP. The developed PLGA based NPs shows promise to be used for cancer therapy.     

Tuning Cellular Response to Nanoparticles via Surface Chemistry and Aggregation

The aggregation of gold nanoparticles (Au NPs) in cell media is a common phenomenon that can influence NP‐cell interactions. Here, we control Au NP aggregation in cell media and study the impact of Au NP aggregation on human dermal fibroblast (HDF) cells. By first adding Au NPs to fetal bovine serum (FBS) and then subsequently to a buffer, aggregation can be avoided. Aggregation of Au NPs also can be avoided by coating Au NPs with other biomolecules such as lipids. The aggregation state of the Au NPs influences cellular toxicity and Au NP uptake: non‐aggregated cationic Au NPs are four‐fold less toxic to HDF cells than aggregated cationic Au NPs, and the uptake of non‐aggregated anionic citrate Au NPs is three orders of magnitude less than that of aggregated citrate Au NPs. Upon uptake of Au NPs, cellular F‐actin fiber formation is disrupted and actin dots are predominant. When lipid‐coated Au NPs are doped with a fluorescent lipid (F‐lipid) and incubated with HDF cells, the fluorescence from the F‐lipid was found throughout the cell, showing that lipids can dissociate from the Au NP surface upon entering the cell.     

Poly (butylene adipate-co-butylene terephthalate) nanoparticles prepared by electrospraying technique for docetaxel delivery in ovarian cancer induced mice

Objective: Ovarian cancer is still a major cause of morbidity and mortality. Docetaxel (DTX) is one of the most notable cytotoxic agents for treatment of ovarian cancer. However, its side effects proposed considerable problems to the patients.

Significance: Polymeric nanoparticles (NPs) of poly (butylene adipate-co-butylene terephthalate) (Ecoflex^®), a biodegradable and biocompatible polymer, were prepared for the first time by the upgradeable electrospraying technique.

Methods: The formulation and procedure variables were optimized using Design Expert software, and effect of each variable on particle size, particle size distribution, drug entrapment efficiency, and drug release of the NPs were evaluated. Then, in vitro cytotoxicity, cellular uptake, X-ray diffraction pattern, and morphological characteristics of the optimized NPs were evaluated. Finally, in vivo efficacy of the DTX-loaded NPs was evaluated on tumor bearing nude mice.

Results: The optimum condition for production of NPs included voltage of 20?kV, 12?cm distance between electrodes, feeding rate of 1?mL/hr, polymer to drug ratio of 3:1, 1 w/v% of Pluronic-F127 and dichloromethane to dimethyl formamide ratio of 2.7:1. Fluorescent microscopy test showed the NPs were successfully up-taken by ovarian cancer cells. In vitro cytotoxicity test confirmed no cytotoxic effect caused by blank NPs, while cell viability of the DTX loaded NPs was significantly lower than the free DTX (p?p?Conclusion: The Ecoflex^® NPs could potentially provide a suitable alternative for currently available formulations of DTX.     

Mechanism of cellular uptake of graphene oxide studied by surface-enhanced Raman spectroscopy

The last few years have witnessed rapid development of biological and medical applications of graphene oxide (GO), such as drug/gene delivery, biosensing, and bioimaging. However, little is known about the cellular uptake mechanism and pathway of GO. In this work, surface-enhanced Raman scattering (SERS) spectroscopy is employed to investigate the cellular internalization of GO loaded with Au nanoparticles (NPs) by Ca Ski cells. The presence of Au NPs on the surface of GO enables detection of enhanced intrinsic Raman signals of GO inside the cell. The SERS results reveal that GO is distributed inhomogeneously inside the cell. Furthermore, internalization of Au-GO into Ca Ski cells is mainly via clathrin-mediated endocytosis, and is an energy-dependent process.     

Conjugated polymer and gold nanoparticle co-loaded PLGA nanocomposites with eccentric internal nanostructure for dual-modal targeted cellular imaging

Herein is reported the one-step synthesis of an integrated nanocomposite with eccentrically loaded 5 nm gold nanoparticles (Au NPs) and conjugated polymer of poly[9,9-bis(6'-N,N,N-trimethylammonium)hexyl)fluorenyldivinylene-alt-4,7-(2,1,3,- benzothiadiazole) dibromide] (PFVBT). The nanocomposite is generated with surface-functionalized folic acid groups due to the matrix polymer of PLGA-PEG(2000) -folate used for encapsulation. The nanocomposite shows far-red fluorescence from PFVBT and scattering signal from Au NPs. Although Au NPs have been widely reported to quench the fluorescence of conjugated polymers, the PFVBT fluorescence is well maintained in the nanocomposite due to the eccentric location of Au NPs. The folic acid groups at the nanocomposite surface favor its cellular uptake by MCF-7 breast cancer cells, which have overexpressed folate receptors on the cell membranes. In conjugation with its low cytotoxicity, the folic-acid-functionalized nanocomposite has been successfully utilized for fluorescence and dark-field dual-modal targeted cellular imaging.     

Synthesis, characterization and transfection of a novel folate-targeted multipolymeric nanoparticles for gene delivery

Novel folate-conjugated biodegradable multipolymeric nanoparticles (NPs) were constructed and evaluated for potential use in gene delivery to human cervical carcinomas Hela cells, which overexpressed folate receptors. Folate-poly(ethylene glycol)-poly(d, l-lactic-co-glycolic acid) (PELGA-F) was synthesized and collaborated with poly-l-lysine (PLL) to form polymer-polycationic peptide-DNA (PPD) NPs. Fluorescein sodium and polylysine-condensed DNA (PD) were encapsulated in both PELGA nanoparticles (PELGA-NPs) and folate modified nanoparticles (PELGA-F-NPs), which were prepared by a modified solvent extraction/evaporation method. Effects of the folate conjugation and PLL introduction on the uptake of NPs was qualified by fluorescent invert microscopy and quantified by spectrofluorometric measurement, while effect on the gene expression was measured by X-gal staining and luciferase assay, both using Hela cells as an in vitro model. Results showed that cellular uptake of NPs was enhanced by folate modification, but had no difference after PLL encapsulation. In transfection tests, increased gene expression also confirmed the different functions of folate and PLL introduction. It is feasible that folate-linked multipolymeric NPs should be an efficient targeted carrier for gene delivery.     

TPGS‐Functionalized Polydopamine‐Modified Mesoporous Silica as Drug Nanocarriers for Enhanced Lung Cancer Chemotherapy against Multidrug Resistance

A nanocarrier system of d ‐a‐tocopheryl polyethylene glycol 1000 succinate (TPGS)‐functionalized polydopamine‐coated mesoporous silica nanoparticles (NPs) is developed for sustainable and pH‐responsive delivery of doxorubicin (DOX) as a model drug for the treatment of drug‐resistant nonsmall cell lung cancer. Such nanoparticles are of desired particle size, drug loading, and drug release profile. The surface morphology, surface charge, and surface chemical properties are also successfully characterized by a series of techniques such as transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), Brunauer‐Emmett‐Teller (BET) method, thermal gravimetric analysis (TGA), dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). The normal A549 cells and drug‐resistant A549 cells are employed to access the cytotoxicity and cellular uptake of the NPs. The therapeutic effects of TPGS‐conjugated nanoparticles are evaluated in vitro and in vivo. Compared with free DOX and DOX‐loaded NPs without TPGS ligand modification, MSNs‐DOX@PDA‐TPGS exhibits outstanding capacity to overcome multidrug resistance and shows better in vivo therapeutic efficacy. This splendid drug delivery platform can also be sued to deliver other hydrophilic and hydrophobic drugs.     

Cyclotron production of radioactive CeO(2) nanoparticles and their application for in vitro uptake studies

Nowadays, a wide variety of nanoparticles (NPs) are applied in different fields such as medical science and industry. Due to their large commercial volume, the OECD Working Party on Manufactured Nanomaterials (NMs) has proposed to study a set of 14 nanomaterials, one of which being cerium oxide (CeO(2)). In particular, CeO(2) based NPs are widely used in automotive industry, healthcare, and cosmetics. In this paper, we propose a method for the production of radioactive CeO(2) NPs.We demonstrate that they maintain the same physicochemical characteristics as the “cold” ones in terms of size distribution and Zeta potential; we develop a new protocol to assess their cellular interaction in immortalized mouse fibroblast cell line Balb/3T3, a model for the study of basal cytotoxicity and carcinogenic potential induced by chemicals and in the present case by NPs. Experimental result of this work, which shows a quasi-linear concentration-uptake response of cells, can be useful as a reference dose-uptake curve for explaining effects following biological uptake after exposure to CeO(2) NPs.     

Design,optimization and evaluation of poly-ɛ-caprolactone (PCL) based polymeric nanoparticles for oral delivery of lopinavir

Lopinavir (LPV)-loaded poly-ε-caprolactone (PCL) nanoparticles (NPs) were prepared by emulsion solvent evaporation technique. Effects of various critical factors in preparation of loaded NPs were investigated. Box–Behnken design (BBD) was employed to optimize particle size and entrapment efficiency (EE) of loaded NPs. Optimized LPV NPs exhibited nanometeric size (195.3?nm) with high EE (93.9%). In vitro drug release study showed bi-phasic sustained release behavior of LPV from NPs. Pharmacokinetic study results in male Wistar rats indicated an increase in oral bioavailability of LPV by 4-folds after incorporation into PCL NPs. From tissue distribution studies, significant accumulation of loaded NPs in tissues like liver and spleen indicated possible involvement of lymphatic route in absorption of NPs. Mechanistic studies using rat everted gut sac model revealed endocytosis as a principal mechanism of NPs uptake. In vitro rat microsomal metabolism studies demonstrated noticeable advantage of LPV NPs by affording metabolic protection to LPV. These studies indicate usefulness of PCL NPs in enhancing oral bioavailability and improving pharmacokinetic profile of LPV.     

Silver nanoparticle synthesis: novel route for laser triggering of polyelectrolyte capsules

We have demonstrated the synthesis of light-sensitive polyelectrolyte capsules (PECs) by utilizing a novel polyol reduction method and investigated its applicability as photosensitive drug delivery vehicle. The nanostructured capsules were prepared via layer by layer (LbL) assembly of poly(allylamine hydrochloride) (PAH) and dextran sulfate (DS) on silica particles followed by in-situ synthesis of silver nanoparticles (NPs). Capsules without silver NPs were permeable to low molecular weight (M(w), 479 g/mol) rhodamine but impermeable to higher molecular weight fluorescence labeled dextran (FITC-dextran). However, capsules synthesized with silver NPs showed porous morphology and were permeable to higher molecular weight (M(w) 70 kDa) FITC-dextran also. These capsules were loaded with FITC-dextran using thermal encapsulation method by exploiting temperature induced shrinking of the capsules. During heat treatment the porous morphology of the capsules transformed into smooth pore free structure which prevents the movement of dextran into bulk during the loading process. When these loaded capsules are exposed to laser pulses, the capsule wall ruptured, resulting in the release of the loaded drug/dye. The rupture of the capsules was dependent on particle size, laser pulse energy and exposure time. The release was linear with time when pulse energy of 400 μJ was used and burst release was observed when pulse energy increased to 600 μJ.     

Intravital Multiphoton Imaging of the Selective Uptake of Water‐Dispersible Quantum Dots into Sinusoidal Liver Cells

Although many studies reporting the organ‐level biodistribution of nanoparticles (NPs) in animals, very few have addressed the fate of NPs in organs at the cellular level. The liver appears to be the main organ for accumulation of NPs after intravenous injection. In this study, for the first time, the in vivo spatiotemporal disposition of recently developed mercaptosuccinic acid (MSA)‐capped cadmium telluride/cadmium sulfide (CdTe/CdS) quantum dots (QDs) is explored in rat liver using multiphoton microscopy (MPM) coupled with fluorescence lifetime imaging (FLIM), with subcellular resolution (～1 μm). With high fluorescence efficiency and largely improved stability in the biological environment, these QDs show a distinct distribution pattern in the liver compared to organic dyes, rhodamine 123 and fluorescein. After intravenous injection, fluorescent molecules are taken up by hepatocytes and excreted into the bile, while negatively charged QDs are retained in the sinusoids and selectively taken up by sinusoidal cells (Kupffer cells and liver sinusoidal endothelial cells), but not by hepatocytes within 3 h. The results could help design NPs targeting the specific types of liver cells and choose the fluorescent markers for appropriate cellular imaging.     

Luteinizing hormone‐releasing hormone targeted poly(methyl vinyl ether maleic acid) nanoparticles for doxorubicin delivery to MCF‐7 breast cancer cells

The purpose of this study was to design a targeted anti‐cancer drug delivery system for breast cancer. Therefore, doxorubicin (DOX) loaded poly(methyl vinyl ether maleic acid) nanoparticles (NPs) were prepared by ionic cross‐linking method using Zn²⁺ ions. To optimise the effect of DOX/polymer ratio, Zn/polymer ratio, and stirrer rate a full factorial design was used and their effects on particle size, zeta potential, loading efficiency (LE, %), and release efficiency in 72 h (RE₇₂, %) were studied. Targeted NPs were prepared by chemical coating of tiptorelin/polyallylamin conjugate on the surface of NPs by using 1‐ethyl‐3‐(3‐dimethylaminopropyl) carboiimid HCl as cross‐linking agent. Conjugation efficiency was measured by Bradford assay. Conjugated triptorelin and targeted NPs were studied by Fourier‐transform infrared spectroscopy (FTIR). The cytotoxicity of DOX loaded in targeted NPs and non‐targeted ones were studied on MCF‐7 cells which overexpress luteinizing hormone‐releasing hormone (LHRH) receptors and SKOV3 cells as negative LHRH receptors using Thiazolyl blue tetrazolium bromide assay. The best results obtained from NPs prepared by DOX/polymer ratio of 5%, Zn/polymer ratio of 50%, and stirrer rate of 960 rpm. FTIR spectrum confirmed successful conjugation of triptorelin to NPs. The conjugation efficiency was about 70%. The targeted NPs showed significantly less IC₅₀ for MCF‐7 cells compared to free DOX and non‐targeted NPs.Inspec keywords: nanoparticles, polymer blends, cancer, cellular biophysics, drug delivery systems, drugs, biomedical materials, zinc, positive ions, Fourier transform infrared spectra, nanomedicine, proteinsOther keywords: luteinizing hormone‐releasing hormone, poly(methyl vinyl ether maleic acid), doxorubicin delivery, MCF‐7 breast cancer cell, anticancer drug delivery system, doxorubicin‐loaded PVM‐MA nanoparticle, ionic cross‐linking method, zinc ion, doxorubicin‐polymer ratio effect, zinc‐polymer ratio effect, particle size, zeta potential, loading efficiency, release efficiency, chemical coating, tiptorelin‐polyallylamin conjugation, PVM‐MA nanoparticle surface, 1‐ethyl‐3‐(3‐dimethylaminopropyl) carboiimid HCl, cross‐linking agent, Bradford assay, Fourier transform infrared spectroscopy, cytotoxicity, LHRH receptor, SKOV3 cell, Thiazolyl blue tetrazolium bromide assay, conjugation efficiency, time 72 h, Zn²⁺      

Polymorph- and size-dependent uptake and toxicity of TiO₂ nanoparticles in living lung epithelial cells

The cellular uptake and distribution of five types of well-characterized anatase and rutile TiO(2) nanoparticles (NPs) in A549 lung epithelial cells is reported. Static light scattering (SLS), in-vitro Raman microspectroscopy (μ-Raman) and transmission electron spectroscopy (TEM) reveal an intimate correlation between the intrinsic physicochemical properties of the NPs, particle agglomeration, and cellular NP uptake. It is shown that μ-Raman facilitates chemical-, polymorph-, and size-specific discrimination of endosomal-particle cell uptake and the retention of particles in the vicinity of organelles, including the cell nucleus, which quantitatively correlates with TEM and SLS data. Depth-profiling μ-Raman coupled with hyperspectral data analysis confirms the location of the NPs in the cells and shows that the NPs induce modifications of the biological matrix. NP uptake is found to be kinetically activated and strongly dependent on the hard agglomeration size-not the primary particle size-which quantitatively agrees with the measured intracellular oxidative stress. Pro-inflammatory responses are also found to be sensitive to primary particle size.     

Surface Functionality of Nanoparticles Determines Cellular Uptake Mechanisms in Mammalian Cells

Nanoparticles (NPs) are versatile scaffolds for numerous biomedical applications including drug delivery and bioimaging. The surface functionality of NPs essentially dictates intracellular NP uptake and controls their therapeutic action. Using several pharmacological inhibitors, it is demonstrated that the cellular uptake mechanisms of cationic gold NPs in both cancer (HeLa) and normal cells (MCF10A) strongly depend on the NP surface monolayer, and mostly involve caveolae and dynamin‐dependent pathways as well as specific cell surface receptors (scavenger receptors). Moreover, these NPs show different uptake mechanisms in cancer and normal cells, providing an opportunity to develop NPs with improved selectivity for delivery applications.     

Uptake Kinetics and Nanotoxicity of Silica Nanoparticles Are Cell Type Dependent

In this study, it is shown that the cytotoxic response of cells as well as the uptake kinetics of nanoparticles (NPs) is cell type dependent. We use silica NPs with a diameter of 310 nm labeled with perylene dye and 304 nm unlabeled particles to evaluate cell type‐dependent uptake and cytotoxicity on human vascular endothelial cells (HUVEC) and cancer cells derived from the cervix carcinoma (HeLa). Besides their size, the particles are characterized concerning homogeneity of the labeling and their zeta potential. The cellular uptake of the labeled NPs is quantified by imaging the cells via confocal microscopy in a time‐dependent manner, with subsequent image analysis via a custom‐made and freely available digital method, Particle_in_Cell‐3D. We find that within the first 4 h of interaction, the uptake of silica NPs into the cytoplasm is up to 10 times more efficient in HUVEC than in HeLa cells. Interestingly, after 10 or 24 h of interaction, the number of intracellular particles for HeLa cells by far surpasses the one for HUVEC. Inhibitor studies show that these endothelial cells internalize 310 nm SiO₂ NPs via the clathrin‐dependent pathway. Remarkably, the differences in the amount of taken up NPs are not directly reflected by the metabolic activity and membrane integrity of the individual cell types. Interaction with NPs leads to a concentration‐dependent decrease in mitochondrial activity and an increase in membrane leakage for HUVEC, whereas HeLa cells show only a reduced mitochondrial activity and no membrane leakage. In addition, silica NPs lead to HUVEC cell death while HeLa cells survive. These findings indicate that HUVEC are more sensitive than HeLa cells upon silica NP exposure.