Dynamic Excimer (DYNEX) Imaging of Lipid Droplets.

Unraveling cellular physiological processes via luminescent probes that target specific cellular microenvironments is quite challenging due to the uneven distribution of probes. Herein, we designed a new dynamic excimer (DYNEX) imaging method that involves the sensitive detection of nanosecond-scale dynamic molecular contacts of a fluorescent acridone derivative and reveals the cell microenvironment polarity. Using our method, we specifically tracked cell lipid droplets in fibroblast colon carcinoma cells. These organelles play a central role in metabolic pathways, acting as energy reservoirs in regulatory processes. DYNEX imaging provides the inner polarity of cell lipid droplets, which can be related to lipid contents and metabolic dysfunctions. This new methodology will inspire development of novel multidimensional fluorescent sensors that are able to provide target-specific and orthogonal information at the nanosecond scale.

Polyethylenimine-Bisphosphonate-Cyclodextrin Ternary Conjugates: Supramolecular Systems for the Delivery of Antineoplastic Drugs.

Bisphosphonates (BPs) are bone-binding molecules that provide targeting capabilities to bone cancer cells when conjugated with drug-carrying polymers. This work reports the design, synthesis, and biological evaluation of polyethyleneimine-BP-cyclodextrin (PEI-BP-CD) ternary conjugates with supramolecular capabilities for the loading of antineoplastic drugs. A straightforward, modular, and versatile strategy based on the click aza-Michael addition reaction of vinyl sulfones (VSs) allows the grafting of BPs targeting ligands and ßCD carrier appendages to the PEI polymeric scaffold. The in vitro evaluation (cytotoxicity, cellular uptake, internalization routes, and subcellular distribution) for the ternary conjugates and their doxorubicin inclusion complexes in different bone-related cancer cell lines (MC3T3-E1 osteoblasts, MG-63 sarcoma cells, and MDA-MB-231 breast cancer cells) confirmed specificity, mitochondrial targeting, and overall capability to mediate a targeted drug transport to those cells. The in vivo evaluation using xenografts of MG-63 and MDA-MB-231 cells on mice also confirmed the targeting of the conjugates.

Poly(ethylene-imine)-Functionalized Magnetite Nanoparticles Derivatized with Folic Acid: Heating and Targeting Properties.

Magnetite nanoparticles (MNPs) coated by branched poly (ethylene-imine) (PEI) were synthesized in a one-pot. Three molecular weights of PEI were tested, namely, 1.8 kDa (sample MNP-1), 10 kDa (sample MNP-2), and 25 kDa (sample MNP-3). The MNP-1 particles were further functionalized with folic acid (FA) (sample MNP-4). The four types of particles were found to behave magnetically as superparamagnetic, with MNP-1 showing the highest magnetization saturation. The particles were evaluated as possible hyperthermia agents by subjecting them to magnetic fields of 12 kA/m strength and frequencies ranging between 115 and 175 kHz. MNP-1 released the maximum heating power, reaching 330 W/g at the highest frequency, in the high side of reported values for spherical MNPs. In vitro cell viability assays of MNP-1 and MNP-4 against three cell lines expressing different levels of FA receptors (FR), namely, HEK (low expression), and HeLa (high expression), and HepG2 (high expression), demonstrated that they are not cytotoxic. When the cells were incubated in the presence of a 175 kHz magnetic field, a significant reduction in cell viability and clone formation was obtained for the high expressing FR cells incubated with MNP-4, suggesting that MNP-4 particles are good candidates for magnetic field hyperthermia and active targeting.

PEI-NIR Heptamethine Cyanine Nanotheranostics for Tumor Targeted Gene Delivery.

Polymer-based nanotheranostics are appealing tools for cancer treatment and diagnosis in the fast-growing field of nanomedicine. A straightforward preparation of novel engineered PEI-based nanotheranostics incorporating NIR fluorescence heptamethine cyanine dyes (NIRF-HC) to enable them with tumor targeted gene delivery capabilities is reported. Branched PEI-2 kDa (b2kPEI) is conjugated with IR-780 and IR-783 dyes by both covalent and noncovalent simple preparative methodologies varying their stoichiometry ratio. The as-prepared set of PEI-NIR-HC nanocarriers are assayed in vitro and in vivo to evaluate their gene transfection efficiency, cellular uptake, cytotoxicity, internalization and trafficking mechanisms, subcellular distribution, and tumor specific gene delivery. The results show the validity of the approach particularly for one of the covalent IR783-b2kPEI conjugates that exhibit an enhanced tumor uptake, probably mediated by organic anion transporting peptides, and favorable intracellular transport to the nucleus. The compound behaves as an efficient nanotheranostic transfection agent in NSG mice bearing melanoma G361 xenographs with concomitant imaging signal and gene concentration in the targeted tumor. By this way, advanced nanotheranostics with multifunctional capabilities (gene delivery, tumor-specific targeting, and NIR fluorescence imaging) are generated in which the NIRF-HC dye component accounts for simultaneous targeting and diagnostics, avoiding additional incorporation of additional tumor-specific targeting bioligands.

In vitro and in vivo evaluation of novel cross-linked saccharide based polymers as bile acid sequestrants.

Bile acid sequestrants (BAS) represent a therapeutic approach for the management of hypercholesterolemia that relies on the cationic polymeric nature of BAS to selectively bind negatively charged bile acids. We hypothesized that the cross-linking of ß-cyclodextrin (ß-CD) and saccharides such as starch or dextrin with divinyl sulfone (DVS) yields homo- and hetero-polymeric materials with the ability to trap sterols. Our hypothesis was put to test by synthesizing a library of 22 polymers that were screened to evaluate their capability to sequester both cholesterol (CHOL) and cholic and deoxycholic acids (CA and DCA). Three polymers synthesized in high yield were identified as promising. Two were neutral hetero-polymers of ß-CD and starch or dextrin and the third was a weakly cationic homo-polymer of starch, highlighting the importance of the cavity effect. They were tested in hypercholesterolemic male Wistar rats and their ability to regulate hypercholesterolemia was similar to that for the reference BAS cholestyramine, but with two additional advantages: (i) they normalized the TG level and (ii) they did not increase the creatinine level. Neither hepatotoxicity nor kidney injury was detected, further supporting them as therapeutical candidates to manage hypercholesterolemia.