Intercalation of antitumor drug doxorubicin and its analogue by DNA duplex: Structural features and biological implications

Multifunctional Molecular Hybrids Photoreleasing Nitric Oxide: Advantages, Pitfalls, and Opportunities

The multifaceted role nitric oxide (NO) plays in human physiology and pathophysiology has opened new scenarios in biomedicine by exploiting this free radical as an unconventional therapeutic against important diseases. The difficulties in handling gaseous NO and the strict dependence of the biological effects on its doses and location have made the light-activated NO precursors, namely NO photodonors (NOPDs), very appealing by virtue of their precise spatiotemporal control of NO delivery. The covalent integration of NOPDs and additional functional components within the same molecular skeleton through suitable linkers can lead to an intriguing class of multifunctional photoactivatable molecular hybrids. In this Perspective, we provide an overview of the recent advances in these molecular constructs, emphasizing those merging NO photorelease with targeting, fluorescent reporting, and phototherapeutic functionalities. We will highlight the rational design behind synthesizing these molecular hybrids and critically describe the advantages, drawbacks, and opportunities they offer in biomedical research.

Establishment of human pluripotent stem cell-derived cortical neurosphere model to study pathomechanisms and chemical toxicity in Kleefstra syndrome

In the present study, we aimed to establish and characterize a mature cortical spheroid model system for Kleefstra syndrome (KS) using patient-derived iPSC. We identified key differences in the growth behavior of KS spheroids determined by reduced proliferation marked by low Ki67 and high E-cadherin expression. Conversely, in the spheroid-based neurite outgrowth assay KS outperformed the control neurite outgrowth due to higher BDNF expression. KS spheroids were highly enriched in VGLUT1/2-expressing glutamatergic and ChAT-expressing cholinergic neurons, while TH-positive catecholamine neurons were significantly underrepresented. Furthermore, high NMDAR1 expression was also detected in the KS spheroid, similarly to other patients-derived neuronal cultures, denoting high NMDAR1 expression as a general, KS-specific marker. Control and KS neuronal progenitors and neurospheres were exposed to different toxicants (paraquat, rotenone, bardoxolone, and doxorubicin), and dose-response curves were assessed after acute exposure. Differentiation stage and compound-specific differences were detected with KS neurospheres being the most sensitive to paraquat. Altogether this study describes a robust 3D model system expressing the disease-specific markers and recapitulating the characteristic pathophysiological traits. This platform is suitable for testing developing brain-adverse environmental effects interactions, drug development, and screening towards individual therapeutic strategies.

Novel platinum therapeutics induce rapid cancer cell death through triggering intracellular ROS storm

Induction of reactive oxygen species (ROS) production in cancer cells plays a critical role for cancer treatment. However, therapeutic efficiency remains challenging due to insufficient ROS production of current ROS inducers. We designed a novel platinum (Pt)-based drug named "carrier-platin" that integrates ultrasmall Pt-based nanoparticles uniformly confined within a poly(amino acids) carrier. Carrier-platin dramatically triggered a burst of ROS in cancer cells, leading to cancer cell death as quick as 30 min. Unlike traditional Pt-based drugs which induce cell apoptosis through DNA intercalation, carrier-platin with superior ROS catalytic activities induces a unique pattern of cancer cell death that is neither apoptosis nor ferroptosis and operates independently of DNA damage. Importantly, carrier-platin demonstrates superior anti-tumor efficacy against a broad spectrum of cancers, particularly those with multidrug resistance, while maintaining minimal systemic toxicity. Our findings reveal a distinct mechanism of action of Pt in cancer cell eradication, positioning carrier-platin as a novel category of anti-cancer chemotherapeutics.

Development of Bivalent Aptamer-DNA Carrier-Doxorubicin Conjugates for Targeted Killing of Esophageal Squamous Cell Carcinoma Cells

Esophageal cancer ranks the seventh in cancer incidence and the sixth in cancer death. Esophageal squamous cell carcinoma (ESCC) accounts for approximately 90% of the total cases of esophageal cancer. Chemotherapy is the most effective drug-based method for treatment of esophageal cancer. However, severe side effects of traditional chemotherapy limit its treatment efficacy. Targeted chemotherapy can deliver chemotherapeutic drugs to cancer cells and specifically kill these cells with reduced side effects. In the work, the bivalent aptamer-DNA carrier (BAD) was designed by using an ESCC cell-specific aptamer as the recognition molecule and a GC base-rich DNA sequence as the drug carrier. With doxorubicin (Dox) as chemotherapeutic drugs, the bivalent aptamer-DNA-Dox conjugate (BADD) was constructed for targeted killing of ESCC cells. Firstly, the truncated A2(35) aptamer with a retained binding ability was obtained through optimization of an intact A2(80) aptamer and was used to fuse with DNA carrier sequences for constructing the BAD through simple DNA hybridization. The results of gel electrophoresis and flow cytometry analysis showed that the BAD was successfully constructed and had a stronger binding affinity than monovalent A2(35). Then, the BAD was loaded with Dox drugs to construct the BADD through noncovalent intercalation. The results of fluorescence spectra and flow cytometry assays showed that the BADD was successfully constructed and can bind to target cells strongly. Confocal imaging further displayed that the BADD can be specifically internalized into target cells and release Dox. The results of CCK-8 assays, Calcein AM/PI staining, and wound healing assays demonstrated that the BADD can specifically kill target cells, but not control cells. Our results demonstrate that the developed BADD can specifically deliver doxorubicin to target ESCC cells and selectively kill these cells, offering a potentially effective strategy for targeted chemotherapy of ESCC.

A comprehensive review on doxorubicin: mechanisms, toxicity, clinical trials, combination therapies and nanoformulations in breast cancer

Doxorubicin is a key treatment for breast cancer, but its effectiveness often comes with significant side effects. Its actions include DNA intercalation, topoisomerase II inhibition, and reactive oxygen species generation, leading to DNA damage and cell death. However, it can also cause heart problems and low blood cell counts. Current trials aim to improve doxorubicin therapy by adjusting doses, using different administration methods, and combining it with targeted treatments or immunotherapy. Nanoformulations show promise in enhancing doxorubicin's effectiveness by improving drug delivery, reducing side effects, and overcoming drug resistance. This review summarizes recent progress and difficulties in using doxorubicin for breast cancer, highlighting its mechanisms, side effects, ongoing trials, and the potential impact of nanoformulations. Understanding these different aspects is crucial in optimizing doxorubicin's use and improving outcomes for breast cancer patients. This review examines the toxicity of doxorubicin, a drug used in breast cancer treatment, and discusses strategies to mitigate adverse effects, such as cardioprotective agents and liposomal formulations. It also discusses clinical trials evaluating doxorubicin-based regimens, the evolving landscape of combination therapies, and the potential of nanoformulations to optimize delivery and reduce systemic toxicity. The review also discusses the potential of liposomes, nanoparticles, and polymeric micelles to enhance drug accumulation within tumor tissues while sparing healthy organs.

Visualized Tracking and Multidimensional Assessing of Mitochondria-Associated Pyroptosis in Cancer Cells by a Small-Molecule Fluorescent Probe

Pyroptosis is closely related to the development and treatment of various cancers; thus, comprehensive studies of the correlations between pyroptosis and its inductive or inhibitive factors can provide new ideas for the intervention and diagnosis of tumors. The dysfunction of mitochondria may induce pyroptosis in cancer cells, which can be reflected by the fluctuations of the microenvironmental parameters in mitochondria as well as the changes of mitochondrial DNA level and morphology, etc. To precisely track and assess the mitochondria-associated pyroptosis process, simultaneous visualization of changes in multiphysiological parameters in mitochondria is highly desirable. In this work, we reported a nonreaction-based, multifunctional small-molecule fluorescent probe Mito-DK with the capability of crosstalk-free response to polarity and mtDNA as well as mitochondrial morphology. Accurate assessment of mitochondria-associated pyroptosis induced by palmitic acid/H2O2 was achieved through monitoring changes in mitochondrial multiple parameters with the help of Mito-DK. In particular, the pyroptosis-inducing ability of an antibiotic doxorubicin and the pyroptosis-inhibiting capacity of an anticancer agent puerarin were evaluated by Mito-DK. These results provide new perspectives for visualizing mitochondria-associated pyroptosis and offer new approaches for screening pyroptosis-related anticancer agents.

A review of the pathophysiological mechanisms of doxorubicin-induced cardiotoxicity and aging

The population of cancer survivors is rapidly increasing due to improving healthcare. However, cancer therapies often have long-term side effects. One example is cancer therapy-related cardiac dysfunction (CTRCD) caused by doxorubicin: up to 9% of the cancer patients treated with this drug develop heart failure at a later stage. In recent years, doxorubicin-induced cardiotoxicity has been associated with an accelerated aging phenotype and cellular senescence in the heart. In this review we explain the evidence of an accelerated aging phenotype in the doxorubicin-treated heart by comparing it to healthy aged hearts, and shed light on treatment strategies that are proposed in pre-clinical settings. We will discuss the accelerated aging phenotype and the impact it could have in the clinic and future research.

Insights into the mechanism of binding of doxorubicin and a chlorin compound with 22-mer c-Myc G quadruplex

BACKGROUND

The interaction of small molecules with G quadruplexes is in focus due to its role in molecular recognition and therapeutic drug design. Stabilization of G-quadruplex structures in the promoter regions of oncogenes by small molecule binding has been demonstrated as a potential approach for cancer therapy.

METHODS

In this study, electronic spectroscopy (ultraviolet-visible, fluorescence, circular dichroism), differential scanning calorimetry, and molecular modeling were employed to explore the interactions between the chemotherapy drug doxorubicin and a chlorin compound 5,10,15,20-tetraphenyl-[2,3]-[bis(carboxy)-methano]chlorin (H2TPC(DAC)), and the c-Myc 22-mer G quadruplex DNA.

RESULTS

Spectroscopic studies indicated external binding of the compounds with partial stacking at the end quartets. Calorimetric studies and temperature dependent circular dichroism data displayed increased melting temperatures of G quadruplex structure on binding with the compounds. Circular dichroism spectra indicated that the G quadruplex structure is intact upon ligand binding. Both the compounds showed binding affinities of the order of 106 M-1. Fluorescence lifetime studies revealed static quenching as major mechanism for fluorescence quenching. Polymerase chain reaction stop assay hinted that binding of both ligands under study could inhibit the amplification of the DNA sequence.

CONCLUSION

Results show that doxorubicin and H2TPC(DAC) bind to the 22-mer c-Myc quadruplex structure with good affinity and induce stability.

SIGNIFICANCE

Doxorubicin and H2TPC(DAC) have demonstrated their affinity towards c-Myc G quadruplex DNA, stabilizing it and inhibiting expression and polymerization. The results can be of practical use in designing new analogs for the two compounds, which can become potent anti-cancer agents targeting the c-Myc GQ structure.

Doxorubicin-induced modulation of TGF-β signaling cascade in mouse fibroblasts: insights into cardiotoxicity mechanisms

Doxorubicin (DOX)-induced cardiotoxicity has been widely observed, yet the specific impact on cardiac fibroblasts is not fully understood. Additionally, the modulation of the transforming growth factor beta (TGF-β) signaling pathway by DOX remains to be fully elucidated. This study investigated DOX's ability to modulate the expression of genes and proteins involved in the TGF-β signaling cascade in mouse fibroblasts from two sources by assessing the impact of DOX treatment on TGF-β inducible expression of pivotal genes and proteins within fibroblasts. Mouse embryonic fibroblasts (NIH3T3) and mouse primary cardiac fibroblasts (CFs) were treated with DOX in the presence of TGF-β1 to assess changes in protein levels by western blot and changes in mRNA levels by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Our results revealed a dose-dependent reduction in cellular communication network factor 2 (CCN2) protein levels upon DOX treatment in both NIH3T3 and CFs, suggesting an antifibrotic activity by DOX in these fibroblasts. However, DOX only inhibited the TGF-β1 induced expression of COL1 in NIH3T3 cells but not in CFs. In addition, we observed that DOX treatment reduced the expression of BMP1 in NIH3T3 but not primary cardiac fibroblasts. No significant changes in SMAD2 protein expression and phosphorylation in either cells were observed after DOX treatment. Finally, DOX inhibited the expression of Atf4 gene and increased the expression of Cdkn1a, Id1, Id2, Runx1, Tgfb1, Inhba, Thbs1, Bmp1, and Stat1 genes in NIH3T3 cells but not CFs, indicating the potential for cell-specific responses to DOX and its modulation of the TGF-β signaling pathway.

Alternating electric fields can improve chemotherapy treatment efficacy in blood cancer cell U937 (non-adherent cells)

BACKGROUND

Recent achievements in cancer therapy are the use of alternating electrical fields at intermediate frequencies (100-300 kHz) and low intensities (1-3 V/cm), which specifically target cell proliferation while affecting different cellular activities depending on the frequency used.

METHODS

In this article, we examine the effect of electric fields on spherical suspended cells and propose the combination of Daunorubicin, a chemotherapy agent widely used in the treatment of acute myeloid leukemia, with electric field exposure. U937 cells were subjected to an electric field with a frequency of 200 kHz and an intensity of 0.75 V/cm, or to a combination of Daunorubicin and electric field exposure, resulting in a significant reduction in cell proliferation. Furthermore, the application of an electric field to U937 cells increased Daunorubicin uptake.

RESULTS

Apoptosis and DNA damage were induced by the electric field or in conjunction with Daunorubicin. Notably, normal cells exposed to an electric field did not show significant damage, indicating a selective effect on dividing cancer cells (U937). Moreover, the electric field affects the U937 cell line either alone or in combination with Daunorubicin. This effect may be due to increased membrane permeability.

CONCLUSIONS

Our findings suggest that the use of electric fields at intermediate frequencies and low intensities, either alone or in combination with Daunorubicin, has potential as a selective anti-cancer therapy for dividing cancer cells, particularly in the treatment of acute myeloid leukemia. Further research is needed to fully understand the underlying mechanisms and to optimize the use of this therapy.

Doxorubicin-Induced Modulation of TGF-β Signaling Cascade in Mouse Fibroblasts: Insights into Cardiotoxicity Mechanisms

Doxorubicin (DOX)-induced cardiotoxicity has been widely observed, yet the specific impact on cardiac fibroblasts is not fully understood. Additionally, the modulation of the transforming growth factor beta (TGF-β) signaling pathway by DOX remains to be fully elucidated. This study investigated DOX's ability to modulate the expression of genes and proteins involved in the TGF-β signaling cascade in mouse fibroblasts from two sources by assessing the impact of DOX treatment on TGF-β inducible expression of pivotal genes and proteins within fibroblasts. Mouse embryonic fibroblasts (NIH3T3) and mouse primary cardiac fibroblasts (CFs) were treated with DOX in the presence of TGF-β1 to assess changes in protein levels by western blot and changes in mRNA levels by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). Our results revealed a dose-dependent reduction in cellular communication network factor 2 (CCN2) protein levels upon DOX treatment in both NIH3T3 and CFs. Moreover, we observed that DOX inhibited the TGF-β1 induced expression of BMP1 in NIH3T3 cells, while BMP1 levels remained high in CFs, and that TGF-β1 induces the phosphorylation of SMAD2 in both NIH3T3 cells and CFs. While DOX treatment diminished the extent of phosphorylation, the reduction did not reach statistical significance. DOX also inhibited the TGF-β1 induced expression of COL1 in NIH3T3 cells and CFs. Finally, DOX inhibited the TGF-β1 induced expression of Atf4 and increased the expression of Cdkn1a, Id1, Id2, Runx1, Tgfb1, Inhba, Thbs1, Bmp1, and Stat1 in NIH3T3 cells but not CFs, indicating the potential for cell-specific responses to DOX and its modulation of the TGF-β signaling pathway. Understanding the underlying mechanisms of the ability of DOX to modulate gene expression and signaling pathways in fibroblasts holds promise for future development of targeted therapeutic strategies to mitigate DOX-induced cardiotoxicity specifically affecting CFs.

Is acriflavine an efficient co-drug in chemotherapy?

Cancer is a global health problem being the second worldwide cause of deaths right after cardiovascular diseases. The main methods of cancer treatment involve surgery, radiation and chemotherapy with an emphasis on the latter. Thus development of nanochemistry and nanomedicine in a search for more effective and safer cancer treatment is an important area of current research. Below, we present interaction of doxorubicin and acriflavine and the cytotoxicity of these drug nano-complexes towards cervical cancer (HeLa) cells. Experimental results obtained from NMR measurements and fluorescence spectroscopy show that the drugs' interaction was due to van der Waals forces, formation of hydrogen bonds and π-π stacking. Quantum molecular simulations confirmed the experimental results with regard to existing π-π stacking. Additionally it was shown that, at the level of theory applied (DFT, triple zeta basis set), the stacking interactions comprise the most preferable interactions (the lowest ΔG ca. -12 kcal mol^-1) both between the molecules forming the acriflavine system and between the other component - another drug (doxorubicin) dimer. Biological tests performed on HeLa cells showed high cytotoxicity of the complexes, comparable to free drugs (ACF and DOX), both after 24 and 48 hours of incubation. For non-cancerous cells, a statistically significant difference in the cytotoxicity of drugs and complexes was observed in the case of a short incubation period. The results of the uptake study showed significantly more efficient cellular uptake of acriflavine than doxorubicin, whether administered alone or in combination with an anthracycline. The mechanism determining the selective uptake of acriflavine and ACF : DOX complexes towards non-cancer and cancer cells should be better understood in the future, as it may be of key importance in the design of complexes with toxic anti-cancer drugs.

SERS Endoscopy for Monitoring Intracellular Drug Dynamics

Understanding the dynamics and distribution of medicinal drugs in living cells is essential for the design and discovery of treatments. The tools available for revealing this information are, however, extremely limited. Here, we report the application of surface-enhanced Raman scattering (SERS) endoscopy, using plasmonic nanowires as SERS probes, to monitor the intracellular fate and dynamics of a common chemo-drug, doxorubicin, in A549 cancer cells. The unique spatio-temporal resolution of this technique reveals unprecedented information on the mode of action of doxorubicin: its localization in the nucleus, its complexation with medium components, and its intercalation with DNA as a function of time. Notably, we were able to discriminate these factors for the direct administration of doxorubicin or the use of a doxorubicin delivery system. The results reported here show that SERS endoscopy may have an important future role in medicinal chemistry for studying the dynamics and mechanism of action of drugs in cells.

Colloidal stability and aggregation behavior of CdS colloids in aquatic systems: Effects of macromolecules, cations, and pH

Redox-dynamic environments such as river floodplains and paddy fields have been demonstrated to be important sources of CdS colloids. To date, the aggregation kinetics of CdS colloids had not yet been studied, and the structure and properties of macromolecules on the interaction between different macromolecules and CdS colloids, as well as the aggregation behavior of CdS colloids are unclear. This study investigated the colloidal stability of CdS colloids in model aqueous systems with various solution chemistry and representative of macromolecules. The results showed that increased electrolyte concentration destabilized CdS colloids by charge screening, with the cationic effect following Ca²⁺ > Mg²⁺ > K⁺ > Na⁺; Higher solution pH stabilized CdS colloids by raising the critical coagulation concentration from 33 to 56 mM NaCl. Electron microscopy and spectroscopy verified the strong interaction between macromolecules and CdS colloids, and macromolecule adsorbed on the surface of CdS to form a protective layer called "NOM corona". The interaction between macromolecules and CdS induced distinct aggregation behaviors in NaCl and CaCl₂ solutions. The steric repulsion generated by "NOM corona" significantly stabilized CdS colloids in NaCl solution, and the stabilizing order was consistent with the adsorbing capacity of macromolecules on CdS colloids, namely Bovine serum albumin (BSA) > sodium alginate (SA) > calf thymus DNA (DNA) > Suwannee River humic acid (HA). BSA and DNA also inhibited CdS colloids aggregation in the CaCl₂ solution due to the balance of steric hindrance, cation bridging, and electrostatic repulsion. For HA and SA, Ca²⁺ bridging and EDL compression contributed to their destabilization of CdS colloids in CaCl₂ solution. Macromolecules concentration affect corona formation that alter stability of CdS colloids. There results showed that the complex influences of solution chemistry and macromolecules on fate and transport of CdS colloids in environment. The findings will help to understand the potential risks of CdS colloids in environment.

Interaction of an anticancer benzopyrane derivative with DNA: Biophysical, biochemical, and molecular modeling studies

BACKGROUND

SIMR1281 is a potent anticancer lead candidate with multi- target activity against several proteins; however, its mechanism of action at the molecular level is not fully understood. Revealing the mechanism and the origin of multitarget activity is important for the rational identification and optimization of multitarget drugs.

METHODS

We have used a variety of biophysical (circular dichroism, isothermal titration calorimetry, viscosity, and UV DNA melting), biochemical (topoisomerase I & II assays) and computational (molecular docking and MD simulations) methods to study the interaction of SIMR1281 with duplex DNA structures.

RESULTS

The biophysical results revealed that SIMR1281 binds to dsDNA via an intercalation-binding mode with an average binding constant of 3.1 × 10⁶ M^-1. This binding mode was confirmed by the topoisomerases' inhibition assays and molecular modeling simulations, which showed the intercalation of the benzopyrane moiety between DNA base pairs, while the remaining moieties (thiazole and phenyl rings) sit in the minor groove and interact with the flanking base pairs adjacent to the intercalation site.

CONCLUSIONS

The DNA binding characteristics of SIMR1281, which can disrupt/inhibit DNA function as confirmed by the topoisomerases' inhibition assays, indicate that the observed multi-target activity might originate from ligand intervention at nucleic acids level rather than due to direct interactions with multiple biological targets at the protein level.

GENERAL SIGNIFICANCE

The findings of this study could be helpful to guide future optimization of benzopyrane-based ligands for therapeutic purposes.

Doxorubicin- and Trastuzumab-Modified Gold Nanoparticles as Potential Multimodal Agents for Targeted Therapy of HER2+ Cancers

Recently, targeted nanoparticles (NPs) have attracted much attention in cancer treatment due to their high potential as carriers for drug delivery. In this article, we present a novel bioconjugate (DOX–AuNPs–Tmab) consisting of gold nanoparticles (AuNPs, 30 nm) attached to chemotherapeutic agent doxorubicin (DOX) and a monoclonal antibody, trastuzumab (Tmab), which exhibited specific binding to HER2 receptors. The size and shape of synthesized AuNPs, as well as their surface modification, were analyzed by the TEM (transmission electron microscopy) and DLS (dynamic light scattering) methods. Biological studies were performed on the SKOV-3 cell line (HER2+) and showed high specificity of binding to the receptors and internalization capabilities, whereas MDA-MB-231 cells (HER2−) did not. Cytotoxicity experiments revealed a decrease in the metabolic activity of cancer cells and surface area reduction of spheroids treated with DOX–AuNPs–Tmab. The bioconjugate induced mainly cell cycle G2/M-phase arrest and late apoptosis. Our results suggest that DOX–AuNPs–Tmab has great potential for targeted therapy of HER2-positive tumors.

Structures and Applications of Nucleic Acid-Based Micelles for Cancer Therapy

Nucleic acids have become important building blocks in nanotechnology over the last 30 years. DNA and RNA can sequentially build specific nanostructures, resulting in versatile drug delivery systems. Self-assembling amphiphilic nucleic acids, composed of hydrophilic and hydrophobic segments to form micelle structures, have the potential for cancer therapeutics due to their ability to encapsulate hydrophobic agents into their core and position functional groups on the surface. Moreover, DNA or RNA within bio-compatible micelles can function as drugs by themselves. This review introduces and discusses nucleic acid-based spherical micelles from diverse amphiphilic nucleic acids and their applications in cancer therapy.

Direct visualization of the drug loading of single DNA origami nanostructures by AFM-IR nanospectroscopy

The efficient loading of DNA nanostructures with intercalating or groove-binding drugs is an important prerequisite for various applications in drug delivery. However, unambiguous verification and quantification of successful drug loading is often rather challenging. In this work, AFM-IR nanospectroscopy is thus employed to directly visualize the loading of DNA origami nanostructures with the photosensitizer methylene blue (MB). Single MB-loaded DNA origami nanostructures can be clearly resolved in high-resolution infrared (IR) maps and the occurrence of MB-specific IR absorption correlates well with the topographic signals of the DNA origami nanostructures. The intensity of the recorded MB absorption bands furthermore scales with the MB concentration used for MB loading. By comparing single- and multilayer DNA origami nanostructures, it is also shown that the IR signal intensity of the loaded MB increases with the thickness of the DNA origami nanostructures. This indicates that also DNA double helices located in the core of bulky 3D DNA origami nanostructures are accessible for MB loading. AFM-IR nanospectroscopy thus has the potential to become an invaluable tool for quantifying drug loading of DNA origami nanostructures and optimizing drug loading protocols.

Phenylboronic acid-modified polymaleic anhydride-F127 micelles for pH-activated targeting delivery of doxorubicin

Phenylboronic acid (PBA) is a tumor-targeting molecule which selectively recognizes sialic acid (SA) overexpressed in tumors. In the study, PBA, F127 and ethanolamine were conjugated with poly(maleic anhydride) by one-step reaction to form amphiphilic polymer for doxorubicin encapsulation. Two drug-carrying micelles with different mass ratio of polymer to drug were prepared by dialysis method to study effect of PBA on doxorubicin release, tumor-targeting and antitumor activity. The study results showed that doxorubicin release from the formulations was acid-sensitive and affected by the polymer dosage, and its acid-induced release behavior improved its insertion into DNA base pairs. Formulation with high polymer dosage showed better tumor targeting and antitumor activity, and activity of inhibiting HepG2 with higher content of SA-containing glycosphingolipids was higher than that of anti-B16. In vivo studies on the activity of B16-bearing mice showed that the doxorubicin-loaded micelles could inhibit the tumor growth and were safer than free doxorubicin. Thus, the PBA-modified nano-polymer micelles have potential biomedical applications due to their nanostructure and tumor-targeting ability.

Amentoflavone-loaded nanoparticles enhanced chemotherapy efficacy by inhibition of AKR1B10

Therapeutic nanoparticles can be combined with different anticancer drugs to achieve a synergistic therapy and avoid the limitations of traditional medicine and thus have clinical prospects for cancer. Herein, an effective nanoplatform was developed for self-assembling AMF@DOX-Fe³⁺-PEG nanoparticles (ADPF NPs) via the coordination of ferric ions (Fe³⁺), amentoflavone (AMF), doxorubicin (DOX), and PEG-polyphenol. The ADPF NPs possessed high drug loading efficiency, good stability and dispersion in water, prolonged blood circulation, and pH-dependent release, which leading to targeted drug transport and enhanced drug accumulation in the tumor. The AMF from the ADPF NPs could inhibit the expression of the Aldo-keto reductase family 1B10 (AKR1B10) and nuclear factor-kappa B p65 (NF-κB p65), which reduced the cardiotoxicity induced by DOX and enhanced the chemotherapy efficacy. This study established a new strategy of combining drug therapy with a nanoplatform. This new strategy has a wide application prospect in clinical tumor therapy.

New Insights into the Mechanism of Action of the Drug Chloroquine: Direct Interaction with DNA and Cytotoxicity

Chloroquine (CLQ) and hydroxychloroquine (HCLQ) are compounds largely employed in the treatment of various human diseases for decades. Nevertheless, a number of intrinsic details concerning their mechanisms of action, especially at the molecular level, are still unknown or have presented controversial results in the literature. Using optical tweezers, here, we investigate at the single-molecule level the molecular mechanism of action of the drug CLQ in its intrinsic interaction with the double-stranded (ds)DNA molecule, one of its targets inside cells, determining the binding modes and the physicochemical (binding) parameters of the interaction. In particular, we show that the ionic strength of the surrounding medium strongly influences such interaction, changing even the main binding mode. In addition, the cytotoxicity of CLQ against three different cell lines was also investigated here, allowing one to evaluate and compare the effect of the drug on the cell viability. In particular, we show that CLQ is highly cytotoxic at a very low (a few micromolar) concentration range for all cell lines tested. These results were rigorously compared to the equivalent ones obtained for the closely related compound hydroxychloroquine (HCLQ), allowing a critical comparison between the action of these drugs at the molecular and cellular levels.

Nanocomposite of electrochemically reduced graphene oxide and gold nanourchins for electrochemical DNA detection

A nanocomposite of graphene oxide and gold nanourchins has been used here to modify the surface of a screen‐printed carbon electrode to enhance the sensitivity of the electrochemical DNA detection system. A specific single‐stranded DNA probe was designed based on the target DNA sequence and was thiolated to be self‐assembled on the surface of the gold nanourchins placed on the modified electrode. Doxorubicin was used as an electrochemical label to detect the DNA hybridisation using differential pulse voltammetry (DPV). The assembling process was confirmed using scanning electron microscopy (SEM) imaging, cyclic voltammetry (CV), and the EIS method. The high sensitivity of the proposed system led to a low detection limit of 0.16 fM and a wide linear range from 0.5 to 950.0 fM. The specificity of the DNA hybridisation and the signalling molecule (haematoxylin) caused very high selectivity towards the target DNA than other non‐specific sequences.

Transforming the Chemical Structure and Bio-Nano Activity of Doxorubicin by Ultrasound for Selective Killing of Cancer Cells

Reconfiguring the structure and selectivity of existing chemotherapeutics represents an opportunity for developing novel tumor-selective drugs. Here, as a proof-of-concept, the use of high-frequency sound waves is demonstrated to transform the nonselective anthracycline doxorubicin into a tumor selective drug molecule. The transformed drug self-aggregates in water to form ≈200 nm nanodrugs without requiring organic solvents, chemical agents, or surfactants. The nanodrugs preferentially interact with lipid rafts in the mitochondria of cancer cells. The mitochondrial localization of the nanodrugs plays a key role in inducing reactive oxygen species mediated selective death of breast cancer, colorectal carcinoma, ovarian carcinoma, and drug-resistant cell lines. Only marginal cytotoxicity (80-100% cell viability) toward fibroblasts and cardiomyocytes is observed, even after administration of high doses of the nanodrug (25-40 µg mL^-1 ). Penetration, cytotoxicity, and selectivity of the nanodrugs in tumor-mimicking tissues are validated by using a 3D coculture of cancer and healthy cells and 3D cell-collagen constructs in a perfusion bioreactor. The nanodrugs exhibit tropism for lung and limited accumulation in the liver and spleen, as suggested by in vivo biodistribution studies. The results highlight the potential of this approach to transform the structure and bioactivity of anticancer drugs and antibiotics bearing sono-active moieties.

Anthracycline derivatives inhibit cardiac CYP2J2

Anthracycline chemotherapeutics are highly effective, but their clinical usefulness is hampered by adverse side effects such as cardiotoxicity. Cytochrome P450 2J2 (CYP2J2) is a cytochrome P450 epoxygenase in human cardiomyocytes that converts arachidonic acid (AA) to cardioprotective epoxyeicosatrienoic acid (EET) regioisomers. Herein, we performed biochemical studies to understand the interaction of anthracycline derivatives (daunorubicin, doxorubicin, epirubicin, idarubicin, 5-iminodaunorubicin, zorubicin, valrubicin, and aclarubicin) with CYP2J2. We utilized fluorescence polarization (FP) to assess whether anthracyclines bind to CYP2J2. We found that aclarubicin bound the strongest to CYP2J2 despite it having large bulky groups. We determined that ebastine competitively inhibits anthracycline binding, suggesting that ebastine and anthracyclines may share the same binding site. Molecular dynamics and ensemble docking revealed electrostatic interactions between the anthracyclines and CYP2J2, contributing to binding stability. In particular, the glycosamine groups in anthracyclines are stabilized by binding to glutamate and aspartate residues in CYP2J2 forming salt bridge interactions. Furthermore, we used iterative ensemble docking schemes to gauge anthracycline influence on EET regioisomer production and anthracycline inhibition on AA metabolism. This was followed by experimental validation of CYP2J2-mediated metabolism of anthracycline derivatives using liquid chromatography tandem mass spectrometry fragmentation analysis and inhibition of CYP2J2-mediated AA metabolism by these derivatives. Taken together, we use both experimental and theoretical methodologies to unveil the interactions of anthracycline derivatives with CYP2J2. These studies will help identify alternative mechanisms of how anthracycline cardiotoxicity may be mediated through the inhibition of cardiac P450, which will aid in the design of new anthracycline derivatives with lower toxicity.

Mode of interaction of altretamine with calf thymus DNA: biophysical insights

Insights into drug-DNA interactions have importance in medicinal chemistry as it has a major role in the evolution of new therapeutic drugs. Therefore, binding studies of small molecules with DNA are of significant interest. Spectroscopy, coupled with measurements of viscosity and molecular docking studies were employed to obtain mechanistic insights into the binding of altretamine with calf thymus DNA (CT-DNA). The UV-visible spectroscopic measurements study confirmed altretamine-CT-DNA complex formation with affinity constant ([15.68 ± 0.04] × 10³ M^-1), a value associated with groove binding phenomenon. The associated thermodynamic signatures suggest enthalpically driven interactions. The values of standard molar free energy change (ΔGmo) -(23.93 ± 0.23) kJ mol^-1, enthalpy change (ΔvHHmo) -(50.84 ± 0.19) kJ mol^-1 and entropy change (ΔSmo) -(90.29 ± 0.12) JK^-1 mol^-1 indicate the binding is thermodynamically favorable and an important role of the hydrogen bonds and Van der Waals interactions in the binding of altretamine with CT-DNA. Circular dichroism spectroscopy indicated insignificant conformational changes in the DNA backbone upon interaction with altretamine suggesting no distortion and/or unstacking of the base pairs in the DNA helix. UV-melting study suggested that the thermal stability of the DNA backbone is not affected by the binding of the drug. Competitive displacement assays with ethidium bromide, Hoechst-33258 and DAPI established the binding of altretamine with CT-DNA in the minor groove. The mode of binding was further confirmed by viscosity and molecular docking studies. Molecular docking further ascertained binding of altretamine in the minor groove of the CT-DNA, preferably with the A-T rich sequences.

Investigation of interactions of doxorubicin with purine nucleobases by molecular modeling

Doxorubicin, an anthracycline antibiotic with anti-tumor activity, is produced by the bacterium Streptomyces peucetius. The interactions between doxorubicin and genetic material and the details of the intercalation with DNA have been controversial issues. Thus, the interactions of doxorubicin with purine nucleobases were studied by quantum mechanical methods. Initially, conformer analyses of doxorubicin were performed with Spartan 08 software and 319 different conformers from 422 initial structures for doxorubicin were obtained. Geometry optimizations and frequency analyses were performed for each structure using density functional theory (DFT) at B3LYP/6-31G** level using Gaussian 09 software. The most stable 20 conformers of doxorubicin and tautomers of purine nucleobases were optimized again with ɷB97XD/6-31G** level and their interactions were also analyzed at the same level. The Discovery Studio 3.5 Visualizer was used to draw the initial and optimized structures of investigated geometries. The noncovalent interactions (NCIs) were visualized by calculating reduced density gradient (RDG) with Multiwfn program. The color-filled isosurfaces and RDG scatter maps of most stable interaction geometries were plotted by Visual Molecular Dynamics (VMD) software and Gnuplot 5.3 software, respectively. This study showed that adenine, guanine, and hypoxanthine nucleobases interact with doxorubicin by forming strong hydrogen bonds and π-π interactions. Considering the normal cellular conditions, the effect of solvent (water) on the interaction geometries were also analyzed and when compared to gas phase it was determined that the movements of the molecules were restricted and there was a minimal change between initial and optimized structures in the aqueous phase.

Molecular Dynamics Assessment of Doxorubicin Adsorption on Surface-Modified Boron Nitride Nanotubes (BNNTs)

Loading therapeutic agents on nanocarriers in order to protect them during drug delivery and exclusively targeting damaged tissues has gained substantial significance in biology realms in the past decade. Boron nitride nanotubes have given a new lease on designing nano delivery systems by virtue of their unique properties. The studies are still ongoing to thoroughly identify their chemical characteristics. In this study, we probed into the efficacy of boron nitride nanotubes and the impact of their surface modification by hydroxyl and amine functional groups in interaction with an anticancer drug model, i.e., doxorubicin. Defining the altered electronic properties of the nanotubes as well as the distribution of partial charges were carried out through density functional theory calculations, following the simulation of the drug loading process via molecular dynamics algorithms. The primary outcomes are inferred from systematical energies, van der Waals and electrostatic interactions, radial distribution functions, the number of hydrogen bonds, mean square displacement, diffusion coefficients, and binding free energies. Negative values of van der Waals energies imply a rapid, exothermic adsorption process whereby the contribution of these driving forces is more dominant than electrostatic ones. Ultimately, the values of overall diffusion coefficients of drugs and binding free energies, performed by the MM/PBSA approach, corroborate that the hydroxyl and amine-functionalized nanotubes reinforce the binding strength of the complexes to an approximate extent.

Facile preparation of nanomicelles using polymyxin E for enhanced antitumor effects

Chemotherapy is a major cancer treatment that uses antitumor drugs to kill fast-growing cancer cells. Many kinds of drug carriers have been developed to deliver and achieve controlled release of small-molecule therapeutic agents. However, many therapeutic agent carriers need complex preparation process. The natural polypeptides may serve as proper drug carriers. More specifically, polymyxin E (PE) is a kind of natural antibiotic lipopeptides. It is commonly used to treat infections caused by multidrug-resistant Gram-negative bacteria. Herein, we present a facile method to prepare DOX-loaded polymyxin E micelles (PE-DOX micelles) to enhance the therapeutic effect of anticancer drug doxorubicin (DOX). The hydrodynamic sizes and zeta potential of the prepared nanomedicine (PE-DOX micelles) were 142.0 nm and 6.47 mV, respectively. The release of DOX from PE-DOX micelles was faster at pH 5.5 than that at pH 7.4. Furthermore, PE exhibited negligible cytotoxicity to A549 cells and HeLa cells within 50 μg/mL, while PE-DOX micelles caused higher cytotoxicity than that of free DOX. Moreover, the intravenously injected PE-DOX micelles showed good biocompatibility and obvious antitumor effect after 14 days' treatment in vivo. The PE-DOX micelles have great potential to be used as anticancer agent in the future.

Prospective Cancer Therapies Using Stimuli-Responsive DNA Nanostructures

Nanostructures based on DNA self-assembly present an innovative way to address the increasing need for target-specific delivery of therapeutic molecules. Currently, most of the chemotherapeutics being used in clinical practice have undesired and exceedingly high off-target toxicity. This is a challenge in particular for small molecules, and hence, developing robust and effective methods to lower these side effects and enhance the antitumor activity is of paramount importance. Prospectively, these issues could be tackled with the help of DNA nanotechnology, which provides a route for the fabrication of custom, biocompatible, and multimodal structures, which can, to some extent, resist nuclease degradation and survive in the cellular environment. Similar to widely employed liposomal products, the DNA nanostructures (DNs) are loaded with selected drugs, and then by employing a specific stimulus, the payload can be released at its target region. This review explores several strategies and triggers to achieve targeted delivery of DNs. Notably, different modalities are explained through which DNs can interact with their respective targets as well as how structural changes triggered by external stimuli can be used to achieve the display or release of the cargo. Furthermore, the prospects and challenges of this technology are highlighted.

2D DNA nanoporous scaffold promotes osteogenic differentiation of pre-osteoblasts

Biofunctional materials with nanomechanical parameters similar to bone tissue may promote the adherence, migration, proliferation, and differentiation of pre-osteoblasts. In this study, deoxyribonucleic acid (DNA) nanoporous scaffold (DNA-NPS) was synthesized by the polymerization of rectangular and double-crossover (DX) DNA tiles. The diagonally precise polymerization of nanometer-sized DNA tiles (A + B) through sticky end cohesion gave rise to a micrometer-sized porous giant-sheet material. The synthesized DNA-NPS exhibited a uniformly distributed porosity with a size of 25 ± 20 nm. The morphology, dimensions, sectional profiles, 2-dimensional (2D) layer height, texture, topology, pore size, and mechanical parameters of DNA-NPS have been characterized by atomic force microscopy (AFM). The size and zeta potential of DNA-NPS have been characterized by the zeta sizer. Cell biocompatibility, proliferation, and apoptosis have been evaluated by flow cytometry. The AFM results confirmed that the fabricated DNA-NPS was interconnected and uniformly porous, with a surface roughness of 0.125 ± 0.08035 nm. The elastic modulus of the DNA-NPS was 22.45 ± 8.65 GPa, which was comparable to that of native bone tissue. DNA-NPS facilitated pre-osteoblast adhesion, proliferation, and osteogenic differentiation. These findings indicated the potential of 2D DNA-NPS in promoting bone tissue regeneration.

The Multifunctionally Graded System for a Controlled Size Effect on Iron Oxide-Gold Based Core-Shell Nanoparticles

We report that Fe3O4@Au core-shell nanoparticles (NPs) serve as a multifunctional molecule delivery platform. This platform is also suitable for sensing the doxorubicin (DOX) through DNA hybridization, and the amount of carried DOX molecules was determined by size-dependent Fe3O4@Au NPs. The limits of detection (LODs) for DOX was found to be 1.839 nM. In our approach, an Au nano-shell coating was coupled with a specially designed DNA sequence using thiol bonding. By means of a high-frequency magnetic field (HFMF), a high release percentage of such a molecule could be efficiently achieved in a relatively short period of time. Furthermore, the thickness increase of the Au nano-shell affords Fe3O4@Au NPs with a larger surface area and a smaller temperature increment due to shielding effects from magnetic field. The change of magnetic property may enable the developed Fe3O4@Au-dsDNA/DOX NPs to be used as future nanocarrier material. More importantly, the core-shell NP structures were demonstrated to act as a controllable and efficient factor for molecule delivery.

Updates on Receptors Targeted by Heterocyclic Scaffolds: New Horizon in Anticancer Drug Development

Anticancer is a high priority research area for scientists as cancer is one of the leading causes of death globally. It is pertinent to mention here that conventional anticancer drugs such as methotrexate, vincristine, cyclophosphamide, etoposide, doxorubicin, cisplatin, etc. are not much efficient for the treatment of different types of cancer; also these suffer from serious side effects leading to therapy failure. A large variety of cancerrelated receptors such as carbonic anhydrase, tyrosine kinase, topoisomerase, protein kinase, histone deacetylase, etc. have been identified which can be targeted by anticancer drugs. Heterocycles like oxadiazole, thiazole, thiadiazole, indole, pyridine, pyrimidine, benzimidazole, etc. play a pivotal role in modern medicinal chemistry because they have a broad spectrum of pharmacological activities including prominent anticancer activity. Therefore, it was considered significant to explore heterocyclic compounds reported in recent most literature which can bind effectively with the cancer-related receptors. This will not only provide a targeted approach to deal with cancer but also the safety profile of the drugs can be further improved. The information provided in this manuscript may be found useful for the design and development of anticancer drugs.

NOXA-mediated degradation of MCL1 and BCL2L1 causes apoptosis of daunorubicin-treated human acute myeloid leukemia cells

Daunorubicin (DNR) is used clinically to treat acute myeloid leukemia (AML), while the signaling pathways associated with its cytotoxicity are not fully elucidated. Thus, we investigated the DNR-induced death pathway in the human AML cell lines U937 and HL-60. DNR-induced apoptosis in U937 cells accompanied by downregulation of MCL1 and BCL2L1, upregulation of Phorbol-12-myristate-13-acetate-induced protein 1 (NOXA), and mitochondrial depolarization. DNR induced NOX4-mediated reactive reactive oxygen species (ROS) production, which in turn inactivated Akt and simultaneously activated p38 mitogen-activated protein kinase (MAPK). Activated p38 MAPK and inactivated Akt coordinately increased GSK3β-mediated cAMP response element-binding protein (CREB) phosphorylation, which promoted NOXA transcription. NOXA upregulation critically increased the proteasomal degradation of MCL1 and BCL2L1. The same pathway was also responsible for the DNR-induced death of HL-60 cells. Restoration of MCL1 or BCL2L1 expression alleviated DNR-induced mitochondrial depolarization and cell death. Furthermore, ABT-199 (a BCL2 inhibitor) synergistically enhanced the cytotoxicity of DNR in AML cell lines. Notably, DNR-induced DNA damage was not related to NOXA-mediated degradation of MCL1 and BCL2L1. Collectively, these results indicate that the upregulation of NOXA expression through the NOX4-ROS-p38 MAPK-GSK3β-CREB axis results in the degradation of MCL1 and BCL2L1 in DNR-treated U937 and HL-60 cells. This signaling pathway may provide insights into the mechanism underlying DNR-triggered apoptosis in AML cells.

Human serum albumin-based doxorubicin prodrug nanoparticles with tumor pH-responsive aggregation-enhanced retention and reduced cardiotoxicity

Doxorubicin (DOX) is a widely-used anticancer drug, but its cardiotoxicity severely hampers its potency in chemotherapy. Herein, human serum albumin (HSA) is engaged as a biocompatible nanocarrier to load a pH-sensitive DOX prodrug, DMDOX, generating HSA-DMDOX nanoparticles via self-assembly driven by hydrophobic interactions. HSA-DMDOX disperses well in a physiological environment (∼40 nm) but aggregates in a tumor acidic microenvironment (pH 6.5, ∼140 nm) owing to the hydrophobicity increase of DMDOX by protonation of carboxylic groups. In vitro anticancer study showed that HSA-DMDOX exhibited enhanced cellular uptake by 4T1 cells and superior cytotoxicity in comparison to HSA-DOX nanoparticles. In vivo study suggested that HSA-DMDOX achieved long blood circulation, aggregation enhanced tumor retention, comparable antitumor efficacy and reduced cardiotoxicity relative to free DOX. Our work presents a facile and effective approach to delivering anthracyclines by HSA-based tumor pH-responsive nanoparticles with aggregation-enhanced tumor retention and reduced toxicity.

Tumor-mediated shape-transformable nanogels with pH/redox/enzymatic-sensitivity for anticancer therapy

Lack of sufficient tumor penetration of the current nanomedicines is a major reason limiting their clinical success in cancer therapy. In this work, we aimed at the development of a novel biodegradable nanoplatform for the selective and controlled delivery of anticancer agents, with improved tumor permeability and the ability to release ultrasmall nanovesicles in the tumor microenvironment. To this end, positively charged nanogels were obtained through the double-crosslinking of chitosan with an ionic physical gelator and a disulfide-containing chemical crosslinker. After conjugation to an anionic oligomer, the cationic nanogels were transformed into negatively charged nanocarriers (CTCP), enabling effective encapsulation of the cationic anticancer agent doxorubicin (DOX) to generate a biodegradable nanomedicine (DOX@CTCP). DOX@CTCP could maintain sustained DOX release and decreased DOX toxicity. Upon arrival at the tumor tissue, the reductive and lysozyme-high microenvironment drives the cleavage of the nanomedicine to release DOX-carrying nanoblocks of smaller size, which together with their acidic-protonable feature achieves an effective therapeutic delivery into cancer cells. The nanomedicine described here showed excellent biocompatibility/biosafety and enhanced in vivo antitumor efficacy.

Improving Breast Cancer Treatment Specificity Using Aptamers Obtained by 3D Cell-SELEX

Three-dimensional spheroids of non-malignant MCF10A and malignant SKBR3 breast cells were used for subsequent 3D Cell-SELEX to generate aptamers for specific binding and treatment of breast cancer cells. Using 3D Cell-SELEX combined with Next-Generation Sequencing and bioinformatics, ten abundant aptamer families with specific structures were identified that selectively bind to SKBR3, and not to MCF10A cells. Multivalent aptamer polymers were synthesized by co-polymerization and analyzed for binding performance as well as therapeutic efficacy. Binding performance was determined by confocal fluorescence imaging and revealed specific binding and efficient internalization of aptamer polymers into SKBR3 spheroids. For therapeutic purposes, DNA sequences that intercalate the cytotoxic drug doxorubicin were co-polymerized into the aptamer polymers. Viability tests show that the drug-loaded polymers are specific and effective in killing SKBR3 breast cancer cells. Thus, the 3D-selected aptamers enhanced the specificity of doxorubicin against malignant over non-malignant breast cells. The innovative modular DNA aptamer platform based on 3D Cell SELEX and polymer multivalency holds great promise for diagnostics and treatment of breast cancer.

The effective transfection of a low dose of negatively charged drug-loaded DNA-nanocarriers into cancer cells via scavenger receptors

DNA-nanotechnology-based nano-architecture scaffolds based on circular strands were designed in the form of DNA-nanowires (DNA-NWs) as a polymer of DNA-triangles. Circularizing a scaffold strand (84-NT) was the critical step followed by annealing with various staple strands to make stiff DNA-triangles. Atomic force microcopy (AFM), native polyacrylamide gel electrophoresis (PAGE), UV-analysis, MTT-assay, flow cytometry, and confocal imaging were performed to assess the formulated DNA-NWs and cisplatin (CPT) loading. The AFM and confocal microscopy images revealed a uniform shape and size distribution of the DNA-NWs, with lengths ranging from 2 to 4 μm and diameters ranging from 150 to 300 nm. One sharp band at the top of the lane (500 bp level) with the loss of electrophoretic mobility during the PAGE (native) gel analysis revealed the successful fabrication of DNA-NWs. The loading efficiency of CPT ranged from 66.85% to 97.35%. MTT and flow cytometry results showed biocompatibility of the blank DNA-NWs even at 95% concentration compared with the CPT-loaded DNA-NWs. The CPT-loaded DNA-NWs exhibited enhanced apoptosis (22%) compared to the apoptosis (7%) induced by the blank DNA-NWs. The release of CPT from the DNA-NWs was sustained at < 75% for 6 h in the presence of serum, demonstrating suitability for systemic applications. The IC50 of CPT@DNA-NWs was reduced to 12.8 nM CPT, as compared with the free CPT solution exhibiting an IC50 of 51.2 nM. Confocal imaging revealed the targetability, surface binding, and slow internalization of the DNA-NWs in the scavenger-receptor-rich cancer cell line (HepG2) compared with the control cell line.

Label-free spectral imaging to study drug distribution and metabolism in single living cells

During drug development, evaluation of drug and its metabolite is an essential process to understand drug activity, stability, toxicity and distribution. Liquid chromatography (LC) coupled with mass spectrometry (MS) has become the standard analytical tool for screening and identifying drug metabolites. Unlike LC/MS approach requiring liquifying the biological samples, we showed that spectral imaging (or spectral microscopy) could provide high-resolution images of doxorubicin (dox) and its metabolite doxorubicinol (dox’ol) in single living cells. Using this new method, we performed measurements without destroying the biological samples. We calculated the rate constant of dox translocating from extracellular moiety into the cell and the metabolism rate of dox to dox’ol in living cells. The translocation rate of dox into a single cell for spectral microscopy and LC/MS approaches was similar (~ 1.5 pM min⁻¹ cell⁻¹). When compared to spectral microscopy, the metabolism rate of dox was underestimated for about every 500 cells using LC/MS. The microscopy approach further showed that dox and dox’ol translocated to the nucleus at different rates of 0.8 and 0.3 pM min⁻¹, respectively. LC/MS is not a practical approach to determine drug translocation from cytosol to nucleus. Using various methods, we confirmed that when combined with a high-resolution imaging, spectral characteristics of a molecule could be used as a powerful approach to analyze drug metabolism. We propose that spectral microscopy is a new method to study drug localization, translocation, transformation and identification with a resolution at a single cell level, while LC/MS is more appropriate for drug screening at an organ or tissue level.

NO release regulated by doxorubicin as the green light-harvesting antenna

We report for the first time a NO photodonor (NOPD) operating with the widely used chemotherapeutic agent doxorubicin (DOX) as the light-harvesting antenna. This permits NO uncaging from an N-nitroso appendage upon selective excitation of DOX with highly biocompatible green light, without precluding its typical red emission. This NOPD effectively binds DNA and photodelivers NO nearby, representing an intriguing candidate for potential multimodal therapeutic applications based on the combination of DOX and NO.

Chemotherapeutic drug-DNA hybrid nanostructures for anti-tumor therapy

Compared to traditional drug delivery systems, DNA nanostructure-based drug delivery systems have several advantages including programmable sequences, precise size and shape, high drug payloads, excellent biocompatibility and biodegradability. To date, a wide range of chemotherapeutic drug-DNA hybrid nanostructures have been developed for anti-tumor therapy. In this review, the constructions of various DNA nanostructures for anticancer drug delivery are firstly summarized. Next, the anticancer drug loading methods for DNA nanostructures are presented. Then, the recent applications of chemotherapeutic drug-DNA hybrid nanostructures for drug delivery are highlighted. In the end, the challenges and opportunities of the chemotherapeutic drug-DNA hybrid nanostructure-based delivery system are discussed. The designs of drug-DNA hybrid systems, including the constructions of nanostructures and the strategies for drug loading, largely influence the efficiency of drug delivery. Recent studies have focused on the development of novel drug-DNA hybrid systems to acquire more precise and efficient therapy for various diseases. A systematic review of the design strategies of chemotherapeutic drug-DNA hybrid nanostructures will benefit the innovation and development of the chemotherapeutic drug-based chemotherapy in clinics.

Mechanical Flexibility of DNA: A Quintessential Tool for DNA Nanotechnology

The mechanical properties of DNA have enabled it to be a structural and sensory element in many nanotechnology applications. While specific base-pairing interactions and secondary structure formation have been the most widely utilized mechanism in designing DNA nanodevices and biosensors, the intrinsic mechanical rigidity and flexibility are often overlooked. In this article, we will discuss the biochemical and biophysical origin of double-stranded DNA rigidity and how environmental and intrinsic factors such as salt, temperature, sequence, and small molecules influence it. We will then take a critical look at three areas of applications of DNA bending rigidity. First, we will discuss how DNA's bending rigidity has been utilized to create molecular springs that regulate the activities of biomolecules and cellular processes. Second, we will discuss how the nanomechanical response induced by DNA rigidity has been used to create conformational changes as sensors for molecular force, pH, metal ions, small molecules, and protein interactions. Lastly, we will discuss how DNA's rigidity enabled its application in creating DNA-based nanostructures from DNA origami to nanomachines.

Multimodal vibrational studies of drug uptake in vitro: Is the whole greater than the sum of their parts?

Herein, we investigated the use of multimodal Raman and infrared (IR) spectroscopic microscopy for the elucidation of drug uptake and subsequent cellular responses. Firstly, we compared different methods for the analysis of the combined data. Secondly, we evaluated whether the combined analysis provided enough benefits to justify the fusion of the data. A459 cells inoculated with doxorubicin (DOX) at different times were fixed and analysed using each technique. Raman spectroscopy provided high sensitivity to DOX and enabled an accurate estimation of the drug uptake at each time point, whereas IR provided a better insight into the resultant changes in the biochemical composition of the cell. In terms of benefits of data fusion, 2D correlation analysis allowed the study of the relationship between IR and Raman variables, whereas the joint analysis of IR and Raman enabled the correlation of the different variables to be monitored over time. In summary, the complementary nature of IR and Raman makes the combination of these vibrational techniques an appealing tool to follow drug kinetics and cellular response.

DNA Nanostructures and DNA-Functionalized Nanoparticles for Cancer Theranostics

In the last two decades, DNA has attracted significant attention toward the development of materials at the nanoscale for emerging applications due to the unparalleled versatility and programmability of DNA building blocks. DNA-based artificial nanomaterials can be broadly classified into two categories: DNA nanostructures (DNA-NSs) and DNA-functionalized nanoparticles (DNA-NPs). More importantly, their use in nanotheranostics, a field that combines diagnostics with therapy via drug or gene delivery in an all-in-one platform, has been applied extensively in recent years to provide personalized cancer treatments. Conveniently, the ease of attachment of both imaging and therapeutic moieties to DNA-NSs or DNA-NPs enables high biostability, biocompatibility, and drug loading capabilities, and as a consequence, has markedly catalyzed the rapid growth of this field. This review aims to provide an overview of the recent progress of DNA-NSs and DNA-NPs as theranostic agents, the use of DNA-NSs and DNA-NPs as gene and drug delivery platforms, and a perspective on their clinical translation in the realm of oncology.

The integrin facilitated internalization of fibronectin-functionalized camptothecin-loaded DNA-nanofibers for high-efficiency anticancer effects

Camptothecin (CMPT) in a free form is extremely cytotoxic as well as hydrophobic drug, and is considered to be highly contagious for systemic administration. The fibronectin (FN)-functionalized DNA-based nanocarrier has been designed to load CMPT and target integrin (αvβ3) receptors which are highly expressed on the A549 cancer cells. Here, we report DNA nanocarrier in the form of DNA-nanofibers (DNA-NFs) capable of loading CMPT via strand intercalation in the GC (base pairs)-rich regions of the DNA duplex. Hence, our keen purpose was to explore the potential of DNA-NFs to load CMPT and assess the improvements of the outcomes in terms of enhanced therapeutic effects to integrin-rich A549 cancer cells with reduced cytotoxic effects to integrin-lacking HEK293 cells. DNA-NFs were formulated as a polymer of DNA triangles. DNA triangles arranged in a programmed way through the complementary overhangs present at the vertices. DNA triangles were primarily obtained through the annealing of the freshly circularized scaffold strands with the three distinct staple strands of specific sequences. The polymerized triangular tiles instead of forming two-dimensional nanosheets underwent self-coiling to give rise to DNA-NF-shaped structures. Flow cytometry and MTT assays were performed to observe cytotoxic and apoptotic effects on integrin-rich A549 cancer cells compared with the integrin-deficient HEK293 cells. AFM, native-page, and confocal experiments confirmed the polymerization of DNA triangles and the morphology of the resulting nanostructures. AFM and confocal images revealed the length of DNA-NFs to be 3-6 μm and the width from 70 to 110 nm. CMPT loading (via strands intercalation) in GC-rich regions of DNA-NFs and the FN functionalization (TAMRA tagged; red fluorescence) via amide chemistry using amino-modified strands of DNA-NFs were confirmed through the UV-shift analysis (> 10 nm shift) and confocal imaging. Blank DNA-NFs were found to be highly biocompatible in 2-640 μM concentrations. MTT assay and flow cytometry experiments revealed that CMPT-loaded DNA-NFs showed a dose-dependent decrease in the cell viability to integrin-rich A549 cancer cells compared with the integrin-deficient HEK293 cells. Conclusively, FN-functionalized, CMPT-loaded DNA-NFs effectively destroyed integrin-rich A549 cancer cells in a targeted manner compared with integrin-deficient HEK293 cells. Grapical abstract.