Fabrication of a Dual-Drug-Loaded Smart Niosome-g-Chitosan Polymeric Platform for Lung Cancer Treatment.

Changes in weather conditions and lifestyle lead to an annual increase in the amount of lung cancer, and therefore it is one of the three most common types of cancer, making it important to find an appropriate treatment method. This research aims to introduce a new smart nano-drug delivery system with antibacterial and anticancer capabilities that could be applied for the treatment of lung cancer. It is composed of a niosomal carrier containing curcumin as an anticancer drug and is coated with a chitosan polymeric shell, alongside Rose Bengal (RB) as a photosensitizer with an antibacterial feature. The characterization results confirmed the successful fabrication of lipid-polymeric carriers with a size of nearly 80 nm and encapsulation efficiency of about 97% and 98% for curcumin and RB, respectively. It had the Korsmeyer-Peppas release pattern model with pH and temperature responsivity so that nearly 60% and 35% of RB and curcumin were released at 37 °C and pH 5.5. Moreover, it showed nearly 50% toxicity against lung cancer cells over 72 h and antibacterial activity against Escherichia coli. Accordingly, this nanoformulation could be considered a candidate for the treatment of lung cancer; however, in vivo studies are needed for better confirmation.

Review on In Silico Methods, High-throughput Screening Techniques, and Cell Culture Based In Vitro Assays for SARS-CoV-2.

The COVID-19 outbreak caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to have high incidence and mortality rate globally. To meet the increasingly growing demand for new therapeutic drugs and vaccines, researchers are developing different diagnostic techniques focused on screening new drugs in clinical use, developing an antibody targeting a SARS-CoV-2 receptor, or interrupting infection/replication mechanisms of SARS-CoV-2. Although many prestigious research publications are addressing this subject, there is no open access platform where all experimental techniques for COVID-19 research can be seen as a whole. Many researchers have accelerated the development of in silico methods, high-throughput screening techniques, and in vitro assays. This development has played an important role in the emergence of improved, innovative strategies, including different antiviral drug development, new drug discovery protocols, combinations of approved drugs, and setting up new drug classes during the COVID-19 outbreak. Hence, the present review discusses the current literature on these modalities, including virtual in silico methods for instant ligand- and target-driven based techniques, nucleic acid amplification tests, and in vitro models based on sensitive cell cultures, tissue equivalents, organoids, and SARS-CoV-2 neutralization systems (lentiviral pseudotype, viral isolates, etc.). This pack of complementary tests informs researchers about the accurate, most relevant emerging techniques available and in vitro assays allow them to understand their strengths and limitations. This review could be a pioneer reference guide for the development of logical algorithmic approaches for new drugs and vaccine strategies against COVID-19.

The neutralization effect of montelukast on SARS-CoV-2 is shown by multiscale in silico simulations and combined in vitro studies.

Small molecule inhibitors have previously been investigated in different studies as possible therapeutics in the treatment of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In the current drug repurposing study, we identified the leukotriene (D4) receptor antagonist montelukast as a novel agent that simultaneously targets two important drug targets of SARS-CoV-2. We initially demonstrated the dual inhibition profile of montelukast through multiscale molecular modeling studies. Next, we characterized its effect on both targets by different in vitro experiments including the enzyme (main protease) inhibition-based assay, surface plasmon resonance (SPR) spectroscopy, pseudovirus neutralization on HEK293T/hACE2+TMPRSS2, and virus neutralization assay using xCELLigence MP real-time cell analyzer. Our integrated in silico and in vitro results confirmed the dual potential effect of montelukast both on the main protease enzyme inhibition and virus entry into the host cell (spike/ACE2). The virus neutralization assay results showed that SARS-CoV-2 virus activity was delayed with montelukast for 20 h on the infected cells. The rapid use of new small molecules in the pandemic is very important today. Montelukast, whose pharmacokinetic and pharmacodynamic properties are very well characterized and has been widely used in the treatment of asthma since 1998, should urgently be completed in clinical phase studies and, if its effect is proved in clinical phase studies, it should be used against coronavirus disease 2019 (COVID-19).

Palladium (II) complex and thalidomide intercept angiogenic signaling via targeting FAK/Src and Erk/Akt/PLCγ dependent autophagy pathways in human umbilical vein endothelial cells.

The current study assessed the effects of the thalidomide and palladium (II) saccharinate complex of terpyridine on the suppression of angiogenesis-mediated cell proliferation. The viability was assessed after treatment with palladium (II) complex (1.56-100 µM) and thalidomide (0.1-400 µM) alone by using ATP assay for 48 h. Palladium (II) complex was found to inhibit growth statistically significant in a dose-dependent manner in HUVECs and promoted PARP-1 cleavage through the production of ROS. On the other hand, thalidomide did not cause any significant change in cell viability. Moreover, cell death was observed to be manifested as late apoptosis due to Annexin V/SYTOX staining after palladium (II) complex treatment however, thalidomide did not demonstrate similar results. Thalidomide and palladium (II) complex also suppressed HUVEC migration and capillary-like structure tube formation in vitro in a time-dependent manner. Palladium (II) complex (5 mg/ml) treatment showed a strong antiangiogenic effect similar to positive control thalidomide (5 mg/ml) and successfully disrupted the vasculature and reduced the thickness of the vessels compared to control (agar). Furthermore, suppression of autophagy enhanced the cell death and anti-angiogenic effect of thalidomide and palladium (II) complex. We also showed that being treated with thalidomide and palladium (II) complex inhibited phosphorylation of the signaling regulators downstream of the VEGFR2. These results provide evidence for the regulation of endothelial cell functions that are relevant to angiogenesis through the suppression of the FAK/Src/Akt/ERK1/2 signaling pathway. Our results also indicate that PLC-γ1 phosphorylation leads to activation of p-Akt and p-Erk1/2 which cause stimulation on cell proliferation at lower doses. Hence, we demonstrated that palladium (II) and thalidomide can induce cell death via the Erk/Akt/PLCγ signaling pathway and that this pathway might be a novel mechanism.

Palladium (II) Complex Enhances ROS-Dependent Apoptotic Effects via Autophagy Inhibition and Disruption of Multiple Signaling Pathways in Colorectal Cancer Cells.

BACKGROUND: Inhibition of autophagy is reported to be a therapeutically effective strategy in overcoming resistance that is a deadly outcome in cancer. One of the most common reasons for chemo-resistance to treatment is the patients with tumors exhibiting a KRAS mutation, which occurs in approximately 40% of colorectal cancer patients. OBJECTIVE: Hence, we assessed whether a Palladium (Pd)(II) complex is a promising anticancer complex, compared to 5-fluorouracil in KRAS wt HT-29 and KRAS mutant HCT-15 cells. METHODS: HCT-15 and HT-29 cells were used for colorectal cancer and Chloroquine (CQ) was used as an inhibitor of autophagy. In this context, cells were treated with Pd(II) complex and 5-FU in combination with CQ for 48h and cell viability was measured by SRB assay. Cell death mode was examined with M30 and M65 ELISA assays, using annexin V/propidium iodide. Autophagy was determined by Acridine Orange (AO) staining. Furthermore, the expressions of various autophagy and apoptosis-related proteins were evaluated with Western blotting. Luminex assay and the level of Reactive Oxygen Species (ROS) were examined. RESULTS: Cell viability was found to decrease in a dose-dependent manner and CQ enhanced cytotoxic effect in Pd(II) and 5-FU treated cells in colorectal cancer cells. Our data showed that inhibition of autophagic flux significantly increased intrinsic apoptosis through the activation of ROS. We showed that combinatorial treatment with CQ induced apoptosis via the caspase-dependent mitochondrial pathway. Luminex analysis revealed that the combination resulted in a down-regulation of NF-κB/AKT/CREB signaling pathways in both cell lines, however, decreased Erk1/2 protein expression was only observed after treatment with CQ combination in HCT-15 cells. CONCLUSION: We suggest that the inhibition of autophagy along with Pd(II) and 5-FU treatment has a synergistic effect on KRAS-mutant colorectal cancer cells. Autophagy inhibition by CQ promotes apoptosis via blockade of the NF-κB/AKT/CREB and activation of ROS.

New manganese(II), iron(II), cobalt(II), nickel(II) and copper(II) saccharinate complexes of 2,6-bis(2-benzimidazolyl)pyridine as potential anticancer agents.

New mononuclear complexes [Mn(NO3)(sac)(H2O)(bzimpy)]·2DMF (Mn), [Fe(sac)2(H2O)(bzimpy)]·2H2O (Fe), [Co(bzimpy)2](sac)2·2H2O (Co), [Ni(bzimpy)2](sac)2·H2O·i-PrOH (Ni) and [Cu(sac)2(bzimpy)]·3DMF (Cu) (sac = saccharinate and bzimpy = 2,6-bis(2-benzimidazolyl)pyridine) were synthesized and structurally characterized by elemental analysis, UV-Vis, IR, ESI-MS and X-ray diffraction. The anticancer activity of the metal complexes against A549 (lung), MCF-7 (breast), HT29 (colon) cancer cells and MCF10A (normal human breast epithelial) cells was tested and compared with those of cisplatin and bzimpy. The complexes displayed potent cytotoxic activity especially in MCF-7 and A549 cell lines, but they were practically inactive against the normal cells. Mechanistic studies with Mn and Cu complexes on A549 cells indicated that the complexes induced G0/G1 arrest. Both complexes increased intracellular ROS (reactive oxygen species) levels and successfully caused both mitochondrial dysfunction and double-strand DNA breaks. The up-regulated Bax and down-regulated Bcl-2 expression levels, caspase-3/7 activation and reduced Fas expression indicated that Mn and Cu induced ROS-dependent mitochondria-mediated intrinsic apoptosis in A549 cells.

Correction: Zn(ii), Cd(ii) and Hg(ii) saccharinate complexes with 2,6-bis(2-benzimidazolyl)pyridine as promising anticancer agents in breast and lung cancer cell lines via ROS-induced apoptosis.

Correction for 'Zn(ii), Cd(ii) and Hg(ii) saccharinate complexes with 2,6-bis(2-benzimidazolyl)pyridine as promising anticancer agents in breast and lung cancer cell lines via ROS-induced apoptosis' by Ceyda Icsel et al., Dalton Trans., 2020, 49, 7842-7851, DOI: .

A promising therapeutic combination for metastatic prostate cancer: Chloroquine as autophagy inhibitor and palladium(II) barbiturate complex.

Autophagy is a catabolic process for cells that can provide energy sources and allows cancer cells to evade cell death. Therefore, studies on the combination of autophagy inhibitors with drugs are increasing as a new treatment modality in cancer. Previously, we reported the anti-tumor activity of a Palladium (Pd)(II) complex against different types of cancer in vitro and in vivo. Chloroquine (CQ), the worldwide used anti-malarial drug, has recently been focused as a chemosensitizer in cancer treatment. The aim of this study was to investigate the efficacy of a combined treatment of these agents that work through different mechanisms to provide an effective treatment modality for metastatic prostate cancer that is certainly fatal. Metastatic prostate cancer cell lines (PC-3 and LNCaP) were treated with Pd (II) complex, CQ, and their combination. The combination enhanced apoptosis by increasing phosphatidylserine translocation and pro-apoptotic proteins. Apoptosis was confirmed by the use of apoptosis inhibitor. The formation of acidic vesicular organelles (AVOs) was observed by acridine orange staining in fluorescence microscopy. The Pd (II) complex increased AVOs formation in prostate cancer cells and CQ-pretreatment has potentiated this effect. Importantly, treatment with CQ suppressed the pro-survival function of autophagy, which might have contributed to enhanced cytotoxicity. In addition, PI3K/AKT/mTOR-related protein expressions were altered after the combination of treatments. Our results suggest that combination treatment enhances apoptotic cell death possibly via the inhibition of autophagy, and may therefore be regarded as a novel and better approach for the treatment of metastatic prostate cancer.

Zn(ii), Cd(ii) and Hg(ii) saccharinate complexes with 2,6-bis(2-benzimidazolyl)pyridine as promising anticancer agents in breast and lung cancer cell lines via ROS-induced apoptosis.

New Zn(ii), Cd(ii) and Hg(ii) complexes of saccharinate (sac) and 2,6-bis(2-benzimidazolyl)pyridine (bzimpy), [Zn(bzimpy)2](sac)2·2H2O (Zn), [Cd(sac)2(bzimpy)] (Cd) and [Hg(sac)2(bzimpy)] (Hg), were prepared and fully characterized by spectroscopic methods and X-ray crystallography. In vitro anticancer screening in A549 (lung), MCF-7 (breast) and HT29 (colon) cell lines showed that Zn was highly cytotoxic against A549 and MCF-7 cells with IC50 values of 1.74 ± 0.06 and 3.15 ± 0.10 µM, respectively, and Hg demonstrated potent cytotoxic activity in MCF-7 cells (8.61 ± 0.98 µM), while Cd and bzimpy exhibited moderate growth inhibitory activities in all of the cell lines. In addition, they showed significantly lower toxicity towards normal human breast epithelial MCF10A cells. Moreover, the complexes exhibited significantly high nuclease activity towards plasmid DNA and their interactions with DNA were assessed by gel electrophoresis and DNA docking. Zn and Hg induced G0/G1 cell arrest and apoptotic cell death detected via typical DNA condensation/fragmentation, annexin V staining and caspase 3/7 activity in A549 and MCF-7 cells. These complexes further caused depolarization of mitochondria and oxidative damage of genomic DNA following excessive production of reactive oxygen species (ROS).

Induction of autophagy enhances apoptotic cell death via epidermal growth factor receptor inhibition by canertinib in cervical cancer cells.

BACKGROUND: It has been known epidermal growth factor receptor (EGFR) frequently overexpressed in cervical cancer. High levels of EGFR expression in their tumors leads to a poor prognosis and inhibition frequently induces autophagy in cancer cells. This study aimed to investigate whether EGFR inhibition by canertinib induces autophagy and this induction influence the effect of Palladium (Pd) (II) complex and 5-fluorouracil (5-FU) especially in nontoxic doses. METHODS: Cytotoxicity was evaluated by using SRB assay. Apoptosis, autophagy, and EGFR key markers were determined by flow cytometry, fluorescence staining, and immunoblotting. Colony formation, invasion, and wound healing assays were performed to investigate cell proliferation, invasion, and migration, respectively. RESULTS: Blocking EGFR by the pan-ErbB tyrosine kinase inhibitor canertinib inhibited cell growth of HeLa cervical cancer cells in combination with Pd(II) complex and 5-FU. Combination of canertinib and Pd(II) complex promotes autophagy and apoptosis of HeLa cancer cells via blockade of the PI3K/AKT and MAPK/ERK pathway, which leads to cervical cancer cell death. ROS accumulation and DNA damage were increased after combinatorial treatment which causes depolarization of the mitochondrial inner membrane and leads to apoptotic cell death. Canertinib combined with Pd(II) complex leads to inhibition of migration and invasion. CONCLUSION: Inhibition of EGFR signaling by canertinib in combination with Pd(II) complex promotes apoptosis and autophagy via blockade of the PI3K/AKT and MAPK/ERK. GENERAL SIGNIFICANCE: The cytotoxic activity of Pd(II) complex and 5-FU on HeLa cells is mediated by EGFR inhibition and autophagy induction, leading to activation of mitochondrial apoptotic cell death.

Bioassay-guided isolation of cytotoxic compounds from Chrysophthalmum montanum (DC.) Boiss.

Bioassay-guided isolation of the 80% methanol extract of the aerial parts of Chrysophthalmum montanum (DC.) Boiss. (Asteraceae) led to the isolation of four known guaianolide-type sesquiterpene lactones, 6α-acetoxy-4α-hydroxy-1ßH-guaia-9.11(13)-dien-12.8α-olide (1), 6α-acetoxy-4α-hydroxy-9ß.10ß-epoxy-1ßH-guaia-11(13)-en-12.8α-olide (2), 4α,6α-dihydroxy-1ß,5α,7αH-guaia-9(10),11(13)-dien-12,8α-olide (3), and (4α,5α,8ß,10ß)-4,10-dihydroxy-1,11(13)-guaidien-12,8-olide (4), along a steroidal glycoside mixture (5a and 5b). The structures of the compounds were identified on the basis of spectroscopic data. Among them, 2, 4 and a steroidal glycoside mixture were obtained from C. montanum for the first time. All isolates were also first time assayed for in vitro cytotoxicities against four human cancer cell lines, i.e. breast (MCF-7, MDA-MB 231), colon (HT-29), and lung (PC3). Among the isolates, 1-3 showed significant inhibitory effect on the proliferation of cancer cells with viability ranging from 6.86 to 26.51%, while steroidal glycoside mixture showed no cytotoxicity, except against HT-29 (viability 61.99%). Compound 4 exhibited strong and selective cell growth inhibition against HT-29 with viability 20.99% and was identified as a promising compound with high selectivity between cancer cells and normal human lung cells (BEAS-2B), especially against HT-29 (IC50 = 12.2 µg/mL) compared to that of cisplatin. These results suggested that 4 is worthy of further study to determine its cytotoxicity mechanisms.

Chloroquine Used in Combination with Chemotherapy Synergistically Suppresses Growth and Angiogenesis In Vitro and In Vivo.

BACKGROUND: The inhibition of autophagy using pharmacological inhibitors such as chloroquine may be an effective strategy to overcome chemotherapy or resistance to anti-angiogenic therapy. MATERIALS AND METHODS: The cytotoxic effect of doxorubicin (0.1-1 µM), chloroquine (0.25-32 µM) and their combination were investigated by employing ATP assay in human umbilical vein endothelial cells (HUVECs). The effect of doxorubicin and chloroquine combination was also measured using tube formation assay on Matrigel. The anti-angiogenic activities of doxorubicin (2.5 µg/pellet) and chloroquine (15 µg/pellet), their combination, and standards (50 µg/pellet) were tested in vivo using the chick embryo chorioallantoic membrane (CAM) assay. RESULTS: The combination of doxorubicin and chloroquine significantly had a stronger anti-angiogenic effect than the positive control (±)-thalidomide and doxorubicin alone in the CAM assay and in vitro tube-formation assay. CONCLUSION: Chloroquine enhanced the anti-angiogenic effect of doxorubicin on CAM at the tested concentrations.

Structures and biochemical evaluation of silver(I) 5,5-diethylbarbiturate complexes with bis(diphenylphosphino)alkanes as potential antimicrobial and anticancer agents.

New silver(I) 5,5-diethylbarbiturate (barb) complexes with a series of bis(diphenylphosphino)alkanes such as 1,1-bis(diphenylphosphino)methane (dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp) and 1,4-bis(diphenylphosphino)butane (dppb) were synthesized and characterized. [Ag2(barb)2(µ-dppm)2] (1), [Ag2(barb)2(µ-dppe)(DMSO)2] (2) and [Ag2(barb)2(µ-dppp)2] (3) were binuclear, while [Ag(barb)(µ-dppb)]n (4) was a coordination polymer. 1-4 effectively bind to the G/C rich region of the major groove of DNA and interact with BSA via hydrophobic interactions in accordance with molecular docking studies. All complexes displayed significant DNA cleavage in the presence of H2O2. 1-4 exhibited more specificity against Gram-positive bacteria than Gram-negative bacteria, but 2 targets both bacterial strains, being comparable to AgNO3 and silver sulfadiazine. Complex 1 has a strong growth inhibitory effect on A549 cells, while 2 and 3 exhibit considerable cytotoxicity against MCF-7 cells. The complexes showed high accumulation in the cytosol fraction of the cells. Mechanistic studies showed that 1 and 2 display effective cell growth inhibition by triggering S and G2/M phase arrest, induce apoptosis via mitochondrial pathways and also damage to DNA due to the overproduction of ROS.

Synthesis, structures and biomolecular interactions of new silver(i) 5,5-diethylbarbiturate complexes of monophosphines targeting Gram-positive bacteria and breast cancer cells.

A series of new silver(i) 5,5-diethylbarbiturate (barb) complexes with the formulas [Ag2(µ-barb)2(PPh3)2] (1), [Ag(barb)(PPh2Cy)] (2), [Ag(barb)(PPhCy2)] (3) and [Ag(barb)(PCy3)] (4) (PPh3 = triphenylphosphine, PPh2Cy = diphenylcyclohexylphosphine, PPhCy2 = dicyclohexylphenylphosphine and PCy3 = tricyclohexylphosphine) were synthesized and fully characterized by elemental analysis, IR, NMR, ESI-MS and X-ray crystallography. All the complexes display a significant affinity towards DNA with a groove binding mode and also strongly bind to BSA via hydrophobic interactions. Lipophilicity increases from 1 to 4 with an increasing number of Cy groups in the phosphine ligands. Screening of the in vitro antimicrobial activity of 1-4 against the strains of Gram-negative (S. typhimurium ATCC 14028, E. coli ATCC 25922 and O157:H7) and Gram-positive (L. garvieae 40456, S. aureus ATCC 25923, and ATCC 33591) bacteria demonstrated that all the complexes exhibit very high activity and specific selectivity against the Gram-positive bacteria, compared to AgNO3 and silver sulfadiazine. Furthermore, the growth inhibitory effects of 1-4 on four human cancer cell lines (MCF-7, PC-3, A549 and HT-29) showed that 4 has a potent cytotoxic activity against MCF-7 cells, significantly higher than cisplatin and carboplatin. The effects of the complexes on the inhibition of the cells are closely related to their lipophilicity as well as DNA/protein binding. The induction of apoptosis of MCF-7 cells treated with 4 was probed through Hoechst 33342 staining, Annexin V positivity and caspase 3/7 activity. In addition, increased ROS levels in the presence of 4 are most likely responsible for damage to both mitochondria and genomic DNA.

Anti-angiogenic effect of a Palladium(II)-Saccharinate Complex of Terpyridine in vitro and in vivo.

Anti-angiogenic activity of palladium (Pd)(II)-based complexes is unknown despite their quite powerful anticancer activity. This study was therefore carried out to evaluate both in vivo anti-angiogenic effect and in vitro cytotoxic activity of a Pd(II)-based complex. ([Pd(sac)(terpy)](sac)·4H2O(sac=saccharinate and terpy=2,2':6',2″-terpyridine)) on HUVEC cells. The anti-angiogenic activity of the complex was evaluated in vivo using the chick embryo chorioallantoic membrane (CAM) assay, tube formation assay and the cytotoxicity was screened using the MTT viability assays. The CAM treated with the complex (50µg/pellet) showed a strikingly high anti-angiogenic effect (score 1.1±0.2) compared to the positive controls cortisone, prednisone and (±)-thalidomide (e.g. (±)-thalidomide score 0.9±0.2) tested at the same concentration. Furthermore, the complex showed neither membrane toxicity nor irritation at the tested concentration. According to the MTT assays, the human umbilical vein endothelial cell (HUVEC) viability was inhibited in a dose-dependent manner at tested concentrations (1.56-100µM). Pd(II) complex also reduced the tube network at the lower dose than the compared with thalidomide. These results suggest that the Pd(II)-complex has strong anti-angiogenic activity, which adds an important feature to the previously-described anticancer activity of the complex.

Enhanced cytotoxic activity of doxorubicin through the inhibition of autophagy in triple negative breast cancer cell line.

BACKGROUND: The outcome of triple negative breast cancer is still poor and requires improvement with better therapy options. Autophagy has recently been shown to play a role in anticancer drug resistance. Therefore, we investigated if the effectiveness of doxorubicin was augmented by the inhibition of autophagy. METHODS: MDA-MB-231 was used as a model cell line for triple negative breast cancer and 3-methyladenine was used as an inhibitor of autophagy. Cells were treated with 0.46-1.84µM doxorubicin and 2.5-10µM 3-methyladenine for 48h. Cell death mode was examined with M30 and M65 ELISA assays. ROS level and LDH activity was examined and the cellular acidic compartment of cells was monitored by acridine orange staining. The expression of various autophagy and apoptosis related proteins/genes were evaluated with Western blotting and RT-qPCR respectively. RESULTS: Synergism was observed between the compounds (CI value<1.0). RT-qPCR analysis revealed that the combination resulted in a down-regulation of autophagy-related genes. Moreover, the combination resulted in a different cell death modality, upregulating necroptosis-related genes. This suggests that the mode of cell death may switch from apoptosis to necroptosis, which is a more severe form of cell death, when autophagy is inhibited. These results were further confirmed at protein level by Western blotting. CONCLUSION: Inhibition of autophagy seems to sensitize triple negative breast cancer cells to doxorubicin, warranting further in vivo studies for the proof of this concept. GENERAL SIGNIFICANCE: Autophagy has a key role in drug resistance in MDA-MB-231 cells. Therefore combinatorial approaches may effectively overcome resistance.

Different DNA immobilization strategies for the interaction of anticancer drug irinotecan with DNA based on electrochemical DNA biosensors.

The interaction of anticancer drug irinotecan (CPT-11) which is the inhibitor of the Topoisomerase I enzyme, with fish sperm double stranded deoxyribonucleic acid (dsDNA) and synthetic short oligonucleotides were studied electrochemically based on the oxidation signals of guanine and CPT-11 by using differential pulse voltammetry (DPV) and cyclic voltammetry (CV) at pencil graphite electrode (PGE). In this work, three types of methods such as adsorption, covalent attachment and electrostatic binding were used for the immobilization of DNA onto the PGE surface. It is found that an effective modification method for DNA on the electrode surface is very important because it shows an effect on the drug and DNA interaction. As a result of the interaction, the electrochemical signal of guanine and CPT-11 greatly decreased. Experimental parameters, such as the effect of buffer solution on the interaction between CPT-11 and DNA, the concentration of CPT-11/DNA, the immobilization time of DNA and the accumulation time of CPT-11 were studied in DPV; in addition, the interaction of CPT-11 with oligonucleotides was evaluated for use as a hybridization indicator in CV and DPV. The detection limit and the reproducibility were also determined.