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Exosomes are nanovesicles formed in the endosomal pathway with an important role in paracrine and autocrine cell communication. Exosomes secreted by cancer cells, malicious exosomes, have important roles in tumor microenvironment maturation and cancer progression. The knowledge of the role of exosomes in tumorigenesis prompted a new era in cancer diagnostics and therapy, taking advantage of the use of circulating exosomes as tumor biomarkers due to their stability in body fluids and targeting malignant exosomes’ release and/or uptake to inhibit or delay tumor development. In recent years, nanotechnology has paved the way for the development of a plethora of new diagnostic and therapeutic platforms, fostering theranostics. The unique physical and chemical properties of gold nanoparticles (AuNPs) make them suitable vehicles to pursuit this goal. AuNPs’ properties such as ease of synthesis with the desired shape and size, high surface:volume ratio, and the possibility of engineering their surface as desired, potentiate AuNPs’ role in nanotheranostics, allowing the use of the same formulation for exosome detection and restraining the effect of malicious exosomes in cancer progression.

Resistance to chemotherapy is a major problem facing current cancer therapy, which is continuously aiming at the development of new compounds that are capable of tackling tumors that developed resistance toward common chemotherapeutic agents, such as doxorubicin (DOX). Alongside the development of new generations of compounds, nanotechnology-based delivery strategies can significantly improve the in vivo drug stability and target specificity for overcoming drug resistance. In this study, multifunctional gold nanoparticles (AuNP) have been used as a nanoplatform for the targeted delivery of an original anticancer agent, a Zn(II) coordination compound [Zn(DION)2]Cl2 (ZnD), toward better efficacy against DOX-resistant colorectal carcinoma cells (HCT116 DR). Selective delivery of the ZnD nanosystem to cancer cells was achieved by active targeting via cetuximab, NanoZnD, which significantly inhibited cell proliferation and triggered the death of resistant tumor cells, thus improving efficacy. In vivo studies in a colorectal DOX-resistant model corroborated the capability of NanoZnD for the selective targeting of cancer cells, leading to a reduction of tumor growth without systemic toxicity. This approach highlights the potential of gold nanoformulations for the targeting of drug-resistant cancer cells.

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A new and never before reported hetero?arylidene?9(10H)?anthrone structure (4) was unexpectedly isolated on reaction of 1,2?dimethyl?3?ethylimidazolium iodide (2) and 9?anthracenecarboxaldehyde (3) under basic conditions. Its structure was unequivocally confirmed by X?ray crystallography. No cytotoxicity in human healthy fibroblasts and in two different cancer cell lines was observed, indicating its applicability in biological systems. Compound 4 interacts with CT?DNA by intercalation between the adjacent base pairs of DNA with a high binding affinity [Kb = 2.0?(±0.20)???105 m?1], which is 10?? higher than that described for doxorubicin [Kb = 3.2?(±0.23)???104 m?1]. Furthermore, compound 4 quenches the fluorescence emission of a GelRed?CT?DNA system with a quenching constant (KSV) of 3.3?(±0.3)???103 m?1 calculated by the Stern?Volmer equation.

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The therapeutic promise of small interfering RNAs (siRNAs) for specific gene silencing is dependent on the
successful delivery of functional siRNAs to the cell cytoplasm. Their conjugation to an established delivery
platform, such as gold nanoparticles, offers a huge potential for treating diseases and advancing our
understanding of cellular processes. The success or failure is dependent on both the uptake of the nanoparticlesinto the cells and subsequent intracellular release of the functional siRNA. In this paper, utilising gold nanoparticle siRNA-mediated delivery against C-MYC, we aimed to determine if we could achieve knockdown in a cancer cell line with low levels of intracellular glutathione, and determine the influence, if any, of polyethylene glycol (PEG) ligand density on knockdown, with a view to determine the optimal nanoparticle
design to achieve C-MYC knockdown. We demonstrate that, regardless of the PEG density, knockdown in cells with relatively low glutathione levels can be achieved, and also the possible effect of steric hindrance in terms of PEG on the availability of the siRNA for cleavage in the intracellular environment. Gold nanoparticle uptake was demonstrated via transmission electron microscopy and mass spectroscopy, whilst knockdown was determined at the protein and physiological levels (cells in S-phase) by in-cell westerns and BrdU incorporation, respectively.

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The design and preparation of highly efficient drug delivery platforms using green methodologies is at the forefront of nanotherapeutics research. POxylated polyurea dendrimers are efficiently synthesized using a supercritical-assisted polymerization in carbon dioxide. These fluorescent, pH-responsive and water-soluble core-shell smart nanocarriers show low toxicity in terms of cell viability and absence of glutathione depletion, two of the major side effect limitations of current vectors. The materials are also found to act as good transfection agents, through a mechanism involving an endosomal pathway, being able to reduce 100-fold the IC50 of paclitaxel.

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The design of small interfering RNA (siRNA) delivery materials showing efficacy in vivo is at the forefront of nanotherapeutics research. Polyurea (PURE-type) dendrimers are ‘smart’ biocompatible 3D polymers that unveil a dynamic and elegant back-folding mechanism involving hydrogen bonding between primary amines at the surface and tertiary amines and ureas at the core. Similarly, to a biological proton pump, they are able to automatically and reversibly transform their conformation in response to pH stimulus. Here, we show that PURE-G4 is a useful gene silencing platform showing no cellular toxicity. As a proof of concept we investigated the PURE-G4-siRNA dendriplex, which was shown to be an attractive platform with high transfection efficacy. The simplicity associated with the complexation of siRNA with polyurea dendrimers makes them a powerful tool for efficient cytosolic siRNA delivery.

Over the past few years, modern medicinal chemistry has evolved towards providing us new and alternative chemotherapeutic compounds with high cytotoxicity towards tumor cells, alongside with reduced side effects in cancer patients. Organometallic compounds and their unique physic-chemical properties typically used in homogenous catalysis are now being translated as potential candidates for medical purposes. Their structural diversity, ligand exchange, redox and catalytic properties make them promising drug candidates for cancer therapy. Over the last decade this area has witnessed a steady growth and a few organometallic compounds have in fact already entered clinical trials, emphasizing its increasing importance and clinical relevance. Here we intend to stress out the different applications of organometallic compounds in medicine with emphasis on cancer therapy, as well as address setbacks regarding formulation issues, systemic toxicity and off-target effects. Advantages over classical coordination metal complexes, their nanovectorisation and specific molecular targets are also discussed.

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