Detection of doxorubicin and metabolites in cell extracts and in single cells by capillary electrophoresis with laser-induced fluorescence detection

Molecular Imprinting Prevents Environmental Contamination and Body Toxicity from Anticancer Drugs: An Update

Cancer has been responsible for high morbidity and mortality globally. The treatment of cancer is possible using different kinds of therapies using anticancer drugs if it is diagnosed at the right time. Nevertheless, their appropriate administration for maximum therapeutic effect and their elimination from the patient's body causing environmental problems are two big issues which could be successfully abated using molecular imprinted polymers (MIPs) owing to their unique features. In this review, we have compiled and discussed the works on the determination and controlled release of anticancer drugs based on MIPs. We also highlighted the current challenges and remedies, and the future direction of MIPs in this area.

Antineoplastic drugs and their analysis: a state of the art review

We provide an overview of the analytical methods available for the quantification of antineoplastic drugs in pharmaceutical formulations, biological and environmental samples.

Nanotherapeutics With Anthracyclines: Methods of Determination and Quantification of Anthracyclines in Biological Samples

Anthracyclines, e.g. doxorubicin, pirarubicin, are widely used as cytostatic agents in the polymer nanotherapeutics designed for the highly effective antitumor therapy with reduced side effects. However, their precise dosage scheme needs to be optimized, which requires an accurate method for their quantification on the cellular level in vitro during nanocarrier development and in body fluids and tissues during testing in vivo. Various methods detecting the anthracycline content in biological samples have already been designed. Most of them are highly demanding and they differ in exactness and reproducibility. The cellular uptake and localization is predominantly observed and determined by microscopy techniques, the anthracycline content is usually quantified by chromatographic analysis using fluorescence detection. We reviewed and compared published methods concerning the detection of anthracycline nanocarriers.

A Flow Cytometric Clonogenic Assay Reveals the Single-Cell Potency of Doxorubicin

Standard cell proliferation assays use bulk media drug concentration to ascertain the potency of chemotherapeutic drugs; however, the relevant quantity is clearly the amount of drug actually taken up by the cell. To address this discrepancy, we have developed a flow cytometric clonogenic assay to correlate the amount of drug in a single cell with the cell's ability to proliferate using a cell tracing dye and doxorubicin, a naturally fluorescent chemotherapeutic drug. By varying doxorubicin concentration in the media, length of treatment time, and treatment with verapamil, an efflux pump inhibitor, we introduced 10(5) -10(10) doxorubicin molecules per cell; then used a dye-dilution assay to simultaneously assess the number of cell divisions. We find that a cell's ability to proliferate is a surprisingly conserved function of the number of intracellular doxorubicin molecules, resulting in single-cell IC50 values of 4-12 million intracellular doxorubicin molecules. The developed assay is a straightforward method for understanding a drug's single-cell potency and can be used for any fluorescent or fluorescently labeled drug, including nanoparticles or antibody-drug conjugates.

Out-of-Plane Plasmonic Antennas for Raman Analysis in Living Cells

Out-of-plane plasmonic nanoantennas protruding from the substrate are exploited to perform very sensitive surface enhanced Raman scattering analysis of living cells. Cells cultured on three-dimensional surfaces exhibit tight adhesion with nanoantenna tips where the plasmonic hot-spot resides. This fact provides observable cell adhesion sites combined with high plasmonic enhancement, resulting in an ideal system for Raman investigation of cell membranes.

Internal standard method for the measurement of doxorubicin and daunorubicin by capillary electrophoresis with in-column double optical-fiber LED-induced fluorescence detection

An internal standard method has been developed for the simultaneous determination of anthracycline antibiotics, doxorubicin (DOX) and daunorubicin (DAN), in rabbit plasma using capillary electrophoresis (CE) with in-column double optical-fiber LED-induced fluorescence detection (CE-ICDOF-LED-FLD). Rhodamine B (RhB) was selected as an internal standard because its emission wavelength is similar to that of the anthracycline antibiotics. Parameters including buffer pH, buffer concentration, organic solvents and separation voltage have been investigated to explore the sensitivity and separation efficiency of DOX and DAN. The optimal electrophoretic separation conditions were a borate buffer (15 mM, pH 9.0) containing 50% acetonitrile (v/v), 10 s hydrodynamic injection at a height of 20 cm and a separation voltage of 15 kV. The developed CE-ICDOF-LED-FLD method provides limits of detection of 18 and 13 ng/mL for DOX and DAN in rabbit plasma samples, respectively. The recoveries ranging from 93.7 to 104.8% and the relative standard deviations at 1.1-1.7% were achieved for DOX and DAN in spiked rabbit plasma samples.

Doxorubicin loaded magnetic gold nanoparticles for in vivo targeted drug delivery

Treatment of approximately 50% of human cancers includes the use of chemotherapy. The major problem associated with chemotherapy is the inability to deliver pharmaceuticals to specific site of the body without inducing normal tissue toxicity. Latterly, magnetic targeted drug delivery (MTD) has been used to improve the therapeutic performance of the chemotherapeutic agents and reduce the severe side effects associated with the conventional chemotherapy for malignant tumors. In this study, we were focused on designing biocompatible magnetic nanoparticles that can be used as a nanocarrier's candidate for MTD regimen. Magnetic gold nanoparticles (MGNPs) were prepared and functionalized with thiol-terminated polyethylene glycol (PEG), then loaded with anti-cancer drug doxorubicin (DOX). The physical properties of the prepared NPs were characterized using different techniques. Transmission electron microscopy (TEM) revealed the spherical mono-dispersed nature of the prepared MGNPs with size about 22 nm. Energy dispersive X-ray spectroscopy (EDX) assured the existence of both iron and gold elements in the prepared nanoparticles. Fourier transform infrared (FTIR) spectroscopy assessment revealed that PEG and DOX molecules were successfully loaded on the MGNPs surfaces, and the amine group of DOX is the active attachment site to MGNPs. In vivo studies proved that magnetic targeted drug delivery can provide a higher accumulation of drug throughout tumor compared with that delivered by passive targeting. This clearly appeared in tumor growth inhibition assessment, biodistribution of DOX in different body organs in addition to the histopathological examinations of treated and untreated Ehrlich carcinoma. To assess the in vivo toxic effect of the prepared formulations, several biochemical parameters such as aspartate aminotransferase (AST), alanine transaminase (ALT), lactate dehydrogenase (LDH), creatine kinase MB (CK-MB), urea, uric acid and creatinine were measured. MTD technology not only minimizes the random distribution of the chemotherapeutic agents, but also reduces their side effects to healthy tissues, which are the two primary concerns in conventional cancer therapies.

Analysis of doxorubicin distribution in MCF-7 cells treated with drug-loaded nanoparticles by combination of two fluorescence-based techniques, confocal spectral imaging and capillary electrophoresis

The intracellular distribution of the antiancer drug doxorubicin (DOX) was followed qualitatively by fluorescence confocal spectral imaging (FCSI) and quantitatively by capillary electrophoresis (CE). FCSI permits the localization of the major fluorescent species in cell compartments, with spectral shifts indicating the polarity of the respective environment. However, distinction between drug and metabolites by FCSI is difficult due to their similar fluorochromes, and direct quantification of their fluorescence is complicated by quantum yield variation between different subcellular environments. On the other hand, capillary electrophoresis with fluorescence detection (CE-LIF) is a quantitative method capable of separating doxorubicin and its metabolites. In this paper, we propose a method for determining drug and metabolite concentration in enriched nuclear and cytosolic fractions of cancer cells by CE-LIF, and we compare these data with those of FCSI. Significant differences in the subcellular distribution of DOX are observed between the drug administered as a molecular solution or as a suspension of drug-loaded iron oxide nanoparticles coated with polyethylene glycol. Comparative analysis of the CE-LIF vs FCSI data may lead to a tentative calibration of this latter method in terms of DOX fluorescence quantum yields in the nucleus and more or less polar regions of the cytosol.

DNA origami as an in vivo drug delivery vehicle for cancer therapy

Many chemotherapeutics used for cancer treatments encounter issues during delivery to tumors in vivo and may have high levels of systemic toxicity due to their nonspecific distribution. Various materials have been explored to fabricate nanoparticles as drug carriers to improve delivery efficiency. However, most of these materials suffer from multiple drawbacks, such as limited biocompatibility and inability to engineer spatially addressable surfaces that can be utilized for multifunctional activity. Here, we demonstrate that DNA origami possessed enhanced tumor passive targeting and long-lasting properties at the tumor region. Particularly, the triangle-shaped DNA origami exhibits optimal tumor passive targeting accumulation. The delivery of the known anticancer drug doxorubicin into tumors by self-assembled DNA origami nanostructures was performed, and this approach showed prominent therapeutic efficacy in vivo. The DNA origami carriers were prepared through the self-assembly of M13mp18 phage DNA and hundreds of complementary DNA helper strands; the doxorubicin was subsequently noncovalently intercalated into these nanostructures. After conducting fluorescence imaging and safety evaluation, the doxorubicin-containing DNA origami exhibited remarkable antitumor efficacy without observable systemic toxicity in nude mice bearing orthotopic breast tumors labeled with green fluorescent protein. Our results demonstrated the potential of DNA origami nanostructures as innovative platforms for the efficient and safe drug delivery of cancer therapeutics in vivo.

Monitoring subcellular biotransformation of N-L-leucyldoxorubicin by micellar electrokinetic capillary chromatography coupled to laser-induced fluorescence detection

Development of prodrugs is a promising alternative to address cytotoxicity and nonspecificity of common anticancer agents. N-L-leucyldoxorubicin (LeuDox) is a prodrug that is biotransformed to the anticancer drug doxorubicin (Dox) in the extracellular space; however, its biotransformation may also occur intracellularly in endocytic organelles. Such organelle-specific biotransformation is yet to be determined. In this study, magnetically enriched endocytic organelle fractions from human uterine sarcoma cells were treated with LeuDox. Micellar electrokinetic chromatography with laser-induced fluorescence detection (MEKC-LIF) was used to determine that 10% of LeuDox was biotransformed to Dox, accounting for ~43% of the biotransformation occurring in the post-nuclear fraction. This finding suggests that endocytic organelles also participate in the intracellular biotransformation of LeuDox to Dox.

DNA origami as a carrier for circumvention of drug resistance

Although a multitude of promising anti-cancer drugs have been developed over the past 50 years, effective delivery of the drugs to diseased cells remains a challenge. Recently, nanoparticles have been used as drug delivery vehicles due to their high delivery efficiencies and the possibility to circumvent cellular drug resistance. However, the lack of biocompatibility and inability to engineer spatially addressable surfaces for multi-functional activity remains an obstacle to their widespread use. Here we present a novel drug carrier system based on self-assembled, spatially addressable DNA origami nanostructures that confronts these limitations. Doxorubicin, a well-known anti-cancer drug, was non-covalently attached to DNA origami nanostructures through intercalation. A high level of drug loading efficiency was achieved, and the complex exhibited prominent cytotoxicity not only to regular human breast adenocarcinoma cancer cells (MCF 7), but more importantly to doxorubicin-resistant cancer cells, inducing a remarkable reversal of phenotype resistance. With the DNA origami drug delivery vehicles, the cellular internalization of doxorubicin was increased, which contributed to the significant enhancement of cell-killing activity to doxorubicin-resistant MCF 7 cells. Presumably, the activity of doxorubicin-loaded DNA origami inhibits lysosomal acidification, resulting in cellular redistribution of the drug to action sites. Our results suggest that DNA origami has immense potential as an efficient, biocompatible drug carrier and delivery vehicle in the treatment of cancer.

Metabolite analyses of single cells

Single-cell analysis is a promising method for understanding not only cellular physiology but also biological mechanisms of multicellular organisms. Although neighboring cells in multicellular organisms originate from the same genomic information, different circumstances around cells or epigenetic differences have different influences on each cell, leading to differing expression of genes, and thus differing levels and dynamics of metabolites, in single cells. However, single-cell analysis is a tough challenge, even with recent technologies, because of the small size of single cells. Unlike genes, metabolites cannot be amplified, and therefore metabolite analysis is another issue. To analyze such a tiny quantity of metabolites in a single cell, various techniques have been tried and developed. Especially in mass spectrometry, marked improvements in both detection sensitivity and ionization techniques have opened up the challenge for the analysis of metabolites in single cells. In this review, we discuss the method for metabolite detection at the level of single cells and recent advancements in technology.

Analysis of the bioactivity of magnetically immunoisolated peroxisomes

Peroxisomes produce reactive oxygen species which may participate in biotransformations of innate biomolecules and xenobiotics. Isolating functional peroxisomes with low levels of contaminants would be a useful tool to investigate biotransformations occurring in these organelles that are usually confounded with biotransformations occurring in other co-isolated organelles. Here, we immunoisolate peroxisomes and demonstrate that the impurity level after isolation is low and that peroxisomes retain their biological activity. In this method, an antibody targeting a 70-kDa peroxisomal membrane protein was immobilized to silanized magnetic iron oxide beads (1-4 μm in diameter) coated with Protein A. Peroxisomes from L6 rat myoblast homogenates were magnetically captured, washed, and then analyzed for subcellular composition using enzymatic assays. Based on the ratio of peroxisomal to lysosomal activity, the retained fraction is 70-fold enriched relative to the unretained fraction. Similarly, the ratio of peroxisomal activity to mitochondrial content suggests that the retained fraction is >30-fold enriched relative to the unretained fraction. H(2)O(2) production from the β-oxidation of palmitoyl-CoA demonstrated that the isolated peroxisomal fraction was biologically active. Capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) analysis confirmed that the immunopurified fractions were capable of transforming the anticancer drug doxorubicin and the fatty acid analog, BODIPY 500/510 C1C12. Besides its use to investigate peroxisome biotransformations in health and disease, the combination of magnetic immunoisolation with CE-LIF could be widely applicable to investigate subcellular-specific biotransformations of xenobiotics occurring at immunoisolated subcellular compartments.

Analysis of anticancer drugs: a review

In the last decades, the number of patients receiving chemotherapy has considerably increased. Given the toxicity of cytotoxic agents to humans (not only for patients but also for healthcare professionals), the development of reliable analytical methods to analyse these compounds became necessary. From the discovery of new substances to patient administration, all pharmaceutical fields are concerned with the analysis of cytotoxic drugs. In this review, the use of methods to analyse cytotoxic agents in various matrices, such as pharmaceutical formulations and biological and environmental samples, is discussed. Thus, an overview of reported analytical methods for the determination of the most commonly used anticancer drugs is given.

Preparation of the core-shell structure adriamycin lipiodol microemulsions and their synergistic anti-tumor effects with diethyldithiocarbamate in vivo

We prepared the core-shell structure adriamycin lipiodol microemulsions (ADM-CSLMs) and evaluated their in vivo antitumor effects in combination with Diethyldithiocarbamate (DDC). Two types of ADM-CSLMs, adriamycin liposome-lipiodol microemulsion(ADM-LLM) and adriamycin microsphere lipiodol microemulsion (ADM-MLM), were prepared through the emulsification method. The drug loading and encapsulation efficiency of ADM-CSLMs were measured by the high-performance liquid chromatograph (HPLC). The size and shape of the ADM-CSLMs were determined by an atom force microscopy (AFM), a transmission electron microscopy (TEM), and a particle size analyzer, respectively. The synergistic effects of DDC and ADM-CSLMs for cancer treatment of carcinoma drug-resistance cell was evaluated by the MTT method, the activation of superoxide dismutase (SOD) was detected by chemiluminescence, and the ADM accumulation in cells was measured by flow cytometry. Walker-256 carcinoma was transplanted to the livers of the male SD rats, ADM-CSLMs were administrated to the livers of the rats by intervention hepatic artery embolization through microsurgery. The tumor growth and animal survival were evaluated. The results show that the average diameter of ADM-LLM and ADM-MLM were 4.23 ± 1.2 μm and 4.67 ± 1.4 μm, respectively, and their ADM encapsulation efficiency were 83.7% and 87.2% with respect to loading efficiency of 82 μg/ml and 91 μg/ml. The tumor growth and animal survival in two of the ADM-CSLMs combined with DDC groups were significantly higher than that of ADM only treatment, ADM liposome combined with DDC (P < 0.01), as well as the ADM microsphere combined with DDC (P < 0.01). Therefore, ADM-CSLMs are useful carriers for the treatment of carcinoma and their anti-tumor effect can be enhanced by DDC in a suitable concentration.

Chemical cytometry quantitates superoxide levels in the mitochondrial matrix of single myoblasts

Triphenylphosphonium hydroethidine (TPP-HE) is a membrane-permeable probe that reacts with superoxide and forms hydroxytriphenylphosphonium ethidium (OH-TPP-E(+)), a fluorescent product that has been previously used in qualitative measurements of superoxide production. In order to develop quantitative methods to measure superoxide, it is necessary to take into consideration the principles that drive TPP-HE accumulation into various subcellular compartments. In the mitochondria matrix, TPP-HE accumulation depends on the mitochondrial membrane potential, which varies from cell to cell. Here we address this issue by including rhodamine 123 (R123) as an internal mitochondrial membrane potential calibrant in chemical cytometry experiments. After loading with TPP-HE and R123, a single cell is lysed within a separation capillary and its contents are separated and detected by micellar electrokinetic capillary chromatography with laser-induced fluorescence detection (MEKC-LIF). Using theoretical arguments, we show that the ratio [OH-TPP-E(+)]/[R123] is adequate to obtain a relative quantitation of mitochondrial matrix superoxide levels for each analyzed cell. We applied this method to single skeletal muscle myoblasts and determined that the steady state superoxide levels in the mitochondrial matrix is approximately (0.29 +/- 0.10) x 10(-12) M. The development of this quantitative method is a critical step toward establishing the importance of reactive oxygen species in biological systems, including those relevant to aging and disease.

Analysis of superoxide production in single skeletal muscle fibers

Due to their high energetic profile, skeletal muscle fibers are prone to damage by endogenous reactive oxygen species (ROS), thereby causing alterations in muscle function. Unfortunately, the complexity of skeletal muscle makes it difficult to measure and understand ROS production by fibers since other components (e.g., extracellular collagen and vascular vessels) may also generate ROS. Single cell imaging techniques are promising approaches to monitor ROS production in single muscle fibers, but usually the detection schemes for ROS are not specific. Single cell analysis by capillary electrophoresis (aka chemical cytometry) has the potential to separate and detect specific ROS reporters, but the approach is only suitable for small spherical cells that fit within the capillary lumen. Here, we report a novel method for the analysis of superoxide in single fibers maintained in culture for up to 48 h. Cultured muscle fibers in individual nanoliter-volume wells were treated with triphenylphosphonium hydroethidine (TPP-HE), which forms the superoxide specific reporter hydroxytriphenylphosphonium ethidium (OH-TPP-E(+)). After lysis of each fiber in their corresponding nanowell, the contents of each well were processed and analyzed by micellar electrokinetic capillary chromatography with laser-induced fluorescence detection (MEKC-LIF) making it possible to detect superoxide found in single fibers. Superoxide basal levels as well as changes due to fiber treatment with the scavenger, tiron, and the inducer, antimycin A, were easily monitored demonstrating the feasibility of the method. Future uses of the method include parallel single-fiber measurements aiming at comparing pharmacological treatments on the same set of fibers and investigating ROS production in response to muscle disease, disuse, exercise, and aging.

Barium Titanate Nanoparticles: Highly Cytocompatible Dispersions in Glycol-chitosan and Doxorubicin Complexes for Cancer Therapy

In the latest years, innovative nanomaterials have attracted a dramatic and exponentially increasing interest, in particular for their potential applications in the biomedical field. In this paper, we reported our findings on the cytocompatibility of barium titanate nanoparticles (BTNPs), an extremely interesting ceramic material. A rational and systematic study of BTNP cytocompatibility was performed, using a dispersion method based on a non-covalent binding to glycol-chitosan, which demonstrated the optimal cytocompatibility of this nanomaterial even at high concentration (100 μg/ml). Moreover, we showed that the efficiency of doxorubicin, a widely used chemotherapy drug, is highly enhanced following the complexation with BTNPs. Our results suggest that innovative ceramic nanomaterials such as BTNPs can be realistically exploited as alternative cellular nanovectors.

Direct sampling from human liver tissue cross sections for electrophoretic analysis of doxorubicin

After chemoembolization of the liver with doxorubicin (Dox), this drug and its metabolites are not homogeneously distributed in this organ. The distribution cannot be easily measured making it difficult to assess how the drug performs in different tissue regions. Here we report a technique for sampling tissue cross sections that can analyze the contents of micrometer size regions. The tissue cross sections were from the explanted liver of a hepatocellular carcinoma patient. Samples were directly aspirated from a 5 microm thick tissue cross section into a 50 microm i.d. capillary where the tissue was solubilized with a separation buffer containing sodium dodecyl sulfate. Upon sample dissolution, Dox and natively fluorescent compounds were separated and detected by micellar electrokinetic chromatography with laser-induced fluorescence detection. Sampling reproducibility and recovery were assessed using 10% (w/v) gelatin as tissue mimic. Sampling from gelatin slices containing Dox revealed a relative standard deviation of 13%, which was comparable to that of sampling from solution. Dox recovery was 82% +/- 16% (n = 5). When sampling tumor and nontumor tissue regions, samples could be taken from the same region 100 microm apart. Atomic force microscopy was used to determine that each sample was 8.4 +/- 1.0 pL in volume which made it possible to determine Dox concentrations in the ranges of 0.4-1.3 and 0.3-0.5 microM for the samples taken from tumor and nontumor regions, respectively. The results demonstrated the feasibility of sampling, detection, and quantification of Dox in micrometer size regions, which could be a useful resource for analyzing the Dox concentration and distribution in highly heterogeneous tissues.

Integrated microfluidic system with chemiluminescence detection for single cell analysis after intracellular labeling

This work describes the first application of microchip electrophoresis with chemiluminescence detection (MCE-CL) in single cell analysis. Human red blood cells were assayed to determine intracellular content of glutathione (GSH). Intracellular GSH was first labeled by incubating cells with diazo-luminol, and then individual cells were injected, in-line lysed, and MCE separated. CL detection was based on the oxidation reaction of luminol-labeled GSH with NaBrO. The MCE-CL assay had a linear calibration curve over a range from 0.2-90 amol GSH injected with a correlation coefficient of 0.9991 and a detection limit of 50 zmol or 3.6 x 10(-9) M (S/N = 3). The average content of GSH in individual human red blood cells was found 64.9 amol (n = 17). Compared with the MCE methods with laser induced fluorescence detection (LIF) reported so far for single cell analysis, the present MCE-CL assay of GSH is simple and about 100 times more sensitive.

A novel system for evaluation of drug mixtures for potential efficacy in treating multidrug resistant cancers

Multidrug resistant (MDR) cancer is difficult to treat. Chemicals that are effective MDR modulators have never exited clinical trials as FDA approved products due to side effects. It has been hypothesized that using a combination of chemotherapeutics with a mixture of MDR modulators (each with different side effects) may lead to useful treatment strategies. Because the experimental space for combination treatments can be large, this space may be impracticable to explore using animal studies. Here we describe an in vitro system based on microfabrication and cell culture that can potentially be used to explore large experimental spaces efficiently. The Microscale Cell Culture Analog (microCCA) concept mimics the body's response using interconnected compartments that represent various tissues or organs. A microCCA is based on the structure of an appropriate physiologically based pharmacokinetic (PBPK) model and emulates the body's dynamic response to exposure to various drugs and chemicals. For this problem we have chosen a microCCA with living cells representing the liver (HepG2/C3A), bone marrow (MEG-01), uterine cancer (MES-SA), and a MDR variant of uterine cancer (MES-SA/DX-5). In proof of concept experiments we found in 24 h "acute" exposures and 72 h treatments that the microCCA system predicts combining the chemotherapeutic, doxorubicin, with cyclosporine and nicardipine, as MDR modulators will have greater efficacy than using doxorubicin by itself or with either modulator alone. This combined strategy is selective in inhibiting MES-SA/DX-5 cell proliferation and may prove to be advantageous in vivo by specifically targeting MDR cancer with acceptable side-effects. This cell specific synergy was not observed in traditional 96-well plate assays. By combining the microCCA with a PBPK model, appropriate drug doses and area under the curve exposure for in vivo trials can be extrapolated directly from the results obtained with this device. This device and approach should be useful in screening potential drug/modulator combinations to determine candidate treatments for MDR cancer. Indeed this approach may be useful for in vitro evaluation of human response to a wide range of exposures to mixtures of chemicals or drugs.

Monitoring incorporation, transformation and subcellular distribution of N-l-leucyl-doxorubicin in uterine sarcoma cells using capillary electrophoretic techniques

Previous reports have demonstrated that N-l-leucyl-doxorubicin (LeuDox) is less toxic than its parent drug, Dox, but the underlying causes of this reduced toxicity have yet to be fully elucidated. In this study, the incorporation of LeuDox into (i) the MES-SA human uterine sarcoma cell line and (ii) its Dox resistant counterpart, MES-SA/Dx5 cell line and the subsequent transformation of LeuDox into Dox and its subcellular distribution, were investigated by micellar electrokinetic chromatography with laser-induced fluorescence detection (MEKC-LIF). In both cell lines the cellular uptakes of Dox and LeuDox were similar at equimolar doses, while the percent transformation of LeuDox into Dox in MES-SA/Dx5 cells was about twice as great as its transformation in MES-SA cells, which is beneficial for reaching Dox cytotoxic levels in this resistant cell line. When both cells lines were treated with IC(35) concentrations of either Dox and LeuDox, the intracellular Dox amounts were 6-fold higher in the resistant cell line than in the sensitive cell line, suggesting that other cellular processes play a role in the cytotoxicity of Dox in the resistant cell line. The amounts and ratios of Dox and LeuDox in four subcellular fractions of LeuDox-treated MES-SA/Dx5 cells were also investigated. The highest Dox/LeuDox ratio (i.e. 2.92) was found in the nuclear fraction, followed by the ratio in the low density organelle fraction (i.e. 1.92) that contains lysosomes, organelles in which lysosomal hydrolytic enzymes, capthesins, transform LeuDox into Dox.

Chemical analysis of single cells

Chemical analysis of single cells requires methods for quickly and quantitatively detecting a diverse array of analytes from extremely small volumes (femtoliters to nanoliters) with very high sensitivity and selectivity. Microelectrophoretic separations, using both traditional capillary electrophoresis and emerging microfluidic methods, are well suited for handling the unique size of single cells and limited numbers of intracellular molecules. Numerous analytes, ranging from small molecules such as amino acids and neurotransmitters to large proteins and subcellular organelles, have been quantified in single cells using microelectrophoretic separation techniques. Microseparation techniques, coupled to varying detection schemes including absorbance and fluorescence detection, electrochemical detection, and mass spectrometry, have allowed researchers to examine a number of processes inside single cells. This review also touches on a promising direction in single cell cytometry: the development of microfluidics for integrated cellular manipulation, chemical processing, and separation of cellular contents.

Comparative study of doxorubicin-loaded poly(lactide-co-glycolide) nanoparticles prepared by single and double emulsion methods

This study describes how the control of doxorubicin (DOX) polarity allows to encapsulate it inside poly(lactide-co-glycolide) (PLGA) nanoparticles formulated either by a single oil-in-water (O/W) or a double water-in-oil-in-water (W/O/W) emulsification method (SE and DE, respectively). DOX is commercially available as a water soluble hydrochloride salt, which is useful for DE. The main difficulty related to DE approach is that the low affinity of hydrophilic drugs to the polymer limits entrapment efficiency. Compared to DE method, SE protocol is easier and should provide an additional gain in entrapment efficiency. To be encapsulated by SE technique, DOX should be used in a more lipophilic molecular form. We evaluated the lipophilicity of DOX in terms of apparent partition coefficient (P) and modulated it by adjusting the pH of the aqueous phase. The highest P values were obtained at pH ranging from 8.6 to 9, i. e. between two DOX pK(a) values (8.2 and 9.6). The conditions favorable for the drug lipophilicity were then used to formulate DOX-loaded PLGA nanoparticles by SE method. DOX encapsulation efficiency as well as release profiles were evaluated for these nanoparticles and compared to those with nanoparticles formulated by DE. Our results indicate that the encapsulation of DOX in nanoparticles formulated by SE provides an increased drug entrapment efficiency and decreases the burst effect.

Coupling chemiluminescence with capillary electrophoresis to analyze single human red blood cells

In this paper, we describe a new method for determination of hemoglobin of single red blood cells by coupling chemiluminescence with capillary electrophoresis (CL-CE). The chemiluminescent detection is based on the catalytic effects of hemoglobin on the luminol-hydrogen peroxide reaction. The conditions of chemiluminescent reaction and capillary electrophoresis were investigated. Hemoglobin in human blood samples was detected with the present method, the linear range from 1.7 microg mL(-1) to 6.8 microg mL(-1) was tested, and the correlation coefficient of 0.997 and low detection limit of 0.17 microg mL(-1) (approximately 2.2 pg, S/N=3) were obtained. Cell injection procedure was improved, and the method was successfully used to determine hemoglobin of single red blood cells and the statistical result of the average content of hemoglobin in 26 human red blood cells was 23.6 pg. Compared to other current methods, CE with CL system is simple, sensitive and will become an attractive alternative method for single cell analysis.

Simultaneous maximization of cell permeabilization and viability in single-cell electroporation using an electrolyte-filled capillary

A549 cells were briefly exposed to Thioglo-1, which converts thiols to fluorescent adducts. The fluorescent cells were exposed to short (50-300 ms) electric field pulses (500 V across a 15 cm capillary) created at the tip of an electrolyte-filled capillary. Fluorescence microscopy revealed varying degrees of cell permeabilization depending on the conditions. Longer pulses and a shorter cell-capillary tip distance led to a greater decrease in the cell's fluorescence. Live/dead (calcein AM and propidium iodide) testing revealed that a certain fraction of cells died. Longer pulses and shorter cell-capillary tip distances were more deadly. An optimum condition exists at a cell-capillary tip distance of 3.5-4.5 microm and a pulse duration of 120-150 ms. At these conditions, >90% of the cells are permeabilized and 80-90% survive.

Analysis of mitochondria isolated from single cells

Bulk studies are not suitable to describe and study cell-to-cell variation, which is of high importance in biological processes such as embryogenesis, tissue differentiation, and disease. Previously, capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) was used to measure the properties of organelles isolated from millions of cells. As such, these bulk measurements reported average properties for the organelles of cell populations. Similar measurements for organelles released from single cells would be highly relevant to describe the subcellular variations among cells. Toward this goal, here we introduce an approach to analyze the mitochondria released from single mammalian cells. Osteosarcoma 143B cells are labeled with either the fluorescent mitochondrion-specific 10-N-nonyl acridine orange (NAO) or via expression of the fluorescent protein DsRed2. Subsequently, a single cell is introduced into the CE-LIF capillary where the organelles are released by a combined treatment of digitonin and trypsin. After this treatment, an electric field is applied and the released organelles electromigrate toward the LIF detector. From an electropherogram, the number of detected events per cell, their individual electrophoretic mobilities, and their individual fluorescence intensities are calculated. The results obtained from DsRed2 labeling, which is retained in intact mitochondria, and NAO labeling, which labels all mitochondria, are the basis for discussion of the strengths and limitations of this single-cell approach.

Micellar electrokinetic capillary chromatography reveals differences in intracellular metabolism between liposomal and free doxorubicin treatment of human leukemia cells

Doxil is a pegylated liposome formulation of the anthracycline doxorubicin. To better explain observed differences in the toxicity of Doxil and free doxorubicin in solution, the intracellular metabolism of the formulations after treatment in CCRF-CEM and CEM/C2 human leukemia cell lines was investigated. Using micellar electrokinetic capillary chromatography with laser-induced fluorescence detection, with a 63 zepto (10(-21)) mole doxorubicin limit of detection, five common metabolites and doxorubicin were detected upon treatment with both of these drug delivery systems. Two unique metabolites appeared with the Doxil and two unique metabolites appeared with the free doxorubicin delivery systems. For common metabolites, the relative amount of metabolite generated from Doxil was approximately 10 times higher than for free doxorubicin.

Accelerator mass spectrometry allows for cellular quantification of doxorubicin at femtomolar concentrations

Accelerator mass spectrometry (AMS) is a highly sensitive analytical methodology used to quantify the content of radioisotopes, such as (14)C, in a sample. The primary goals of this work were to demonstrate the utility of AMS in determining total cellular [(14)C]anthracycline concentrations following administration of doxorubicin (DOX) and to develop a sensitive assay that is superior to high performance liquid chromatography (HPLC) for the quantification of [(14)C]anthracycline at the tumor level. In order to validate the sensitivity of AMS versus HPLC with fluorescence detection, we performed three studies comparing the cellular accumulation of DOX: one in vitro cell line study, and two in vivo xenograft mouse studies. Using AMS, we quantified cellular [(14)C]anthracycline content up to 4 h following in vitro exposure at concentrations ranging from 0.2 pg/ml (345 fM) to 2 microg/ml (3.45 microM) [(14)C]DOX. The results of this study show that, compared to standard fluorescence-based HPLC, the AMS method was over five orders of magnitude more sensitive. Two in vivo studies compared the sensitivity of AMS to HPLC using a nude mouse xenograft model in which breast cancer cells were implanted subcutaneously. After sufficiently large tumors formed, [(14)C]DOX was administered intravenously at two dose levels. Additionally, we tested the AMS method in a nude mouse xenograft model of multidrug resistance (MDR) in which each mouse was implanted with both wild type and MDR+ cells on opposite flanks. The results of the second and third studies showed that [(14)C]anthracycline concentrations were significantly higher in the wild type tumors compared to the MDR+ tumors, consistent with the MDR model. Although this method does not discriminate between parent drug and metabolites, the extreme sensitivity of AMS should facilitate similar studies in humans to establish target site drug delivery and to potentially determine the optimal treatment dose and regimen.

Measuring the Doxorubicin Content of Single Nuclei by Micellar Electrokinetic Capillary Chromatography with Laser-Induced Fluorescence Detection

Individual nuclei isolated from the human leukemia CCRF-CEM and CEM-C2 cells treated with doxorubicin (DOX) were in-column lysed with a sodium dodecyl sulfate (SDS) containing buffer, their contents were then separated by micellar electrokinetic capillary chromatography using the same lysing buffer, and the DOX content was detected by laser-induced fluorescence. Use of a microscope for the selection of one nucleus from the nuclear preparation decreases the possibility of introduction of other subcellular components that are commonly found as impurities in subcellular fractions. The presence of SDS in the running buffer made negligible the DNA's quenching effect on DOX fluorescence, which often compromises quantification of DOX by direct imaging, making it possible to carry out the first direct measurement of the doxorubicin content of isolated nuclei. On average, nuclei from CCRF-CEM and CEM/C2 cell lines contained 85 +/-64 (n = 6) and 91 +/- 51 (n =7) amol of DOX, respectively. These values correspond to 74 and 65% of the average total cellular content as determined by single-cell analysis of the corresponding cell types. It is envisioned that this approach could become an important bioanalytical tool to investigate the effect of treatments with fluorescent drugs targeting the nucleus.