In Vitro and Preclinical Antitumor Evaluation of Doxorubicin Liposomes Coated with a Cholesterol-Based Trimeric ß-D-Glucopyranosyltriazole.

The coating of liposomes with polyethyleneglycol (PEG) has been extensively discussed over the years as a strategy for enhancing the in vivo and in vitro stability of nanostructures, including doxorubicin-loaded liposomes. However, studies have shown some important disadvantages of the PEG molecule as a long-circulation agent, including the immunogenic role of PEG, which limits its clinical use in repeated doses. In this context, hydrophilic molecules as carbohydrates have been proposed as an alternative to coating liposomes. Thus, this work studied the cytotoxicity and preclinical antitumor activity of liposomes coated with a glycosyl triazole glucose (GlcL-DOX) derivative as a potential strategy against breast cancer. The glucose-coating of liposomes enhanced the storage stability compared to PEG-coated liposomes, with the suitable retention of DOX encapsulation. The antitumor activity, using a 4T1 breast cancer mouse model, shows that GlcL-DOX controlled the tumor growth in 58.5% versus 35.3% for PEG-coated liposomes (PegL-DOX). Additionally, in the preliminary analysis of the GlcL-DOX systemic toxicity, the glucose-coating liposomes reduced the body weight loss and hepatotoxicity compared to other DOX-treated groups. Therefore, GlcL-DOX could be a promising alternative for treating breast tumors. Further studies are required to elucidate the complete GlcL-DOX safety profile.

Polymer-hybrid nanosystems for antiviral applications: Current advances.

The emergence of many new viruses in recent times has resulted in a significant scientific challenge for discovering drugs and vaccines that effectively treat and prevent viral diseases. Nanotechnology has opened doors to prevent the spread of several diseases, including those caused by viruses. Polymer-hybrid nanodevices are a class of nanotechnology platforms for biomedical applications that present synergistic properties among their components, with improved performance compared to conventional forms of therapy. Considering the growing interest in this emerging field and the promising technological advantages of polymer-hybrid nanodevices, this work presents the current status of these systems in the context of prevention and treatment of viral diseases. A brief description of the different types of polymer-hybrid nanodevices highlighting some peculiar characteristics such as their composition, biodistribution, delivery of antigens, and overall immune responses in systemic tissues are discussed. Finally, the work presents the future trends for new nanotechnological hybrid materials based on polymers and perspectives for clinical use.

Ferri-Liposomes: Preformulation and Selective Cytotoxicity against A549 Lung Cancer Cells.

Liposomes have become successful nanostructured systems used in clinical practices. These vesicles are able to carry important drug loadings with noteworthy stability. The aim of this work was to develop iron oxide-loaded stealth liposomes as a prospective alternative for the treatment of lung cancer. In this study, citric acid iron oxide nanoparticles (IONPs-Ac) were synthesized and encapsulated in stealth liposomes. Their cytotoxicity and selectivity against lung tumor cells were assessed. Stealth liposomal vesicles, with relevant content of IONPs-Ac, named ferri-liposomes (SL-IONPs-Ac), were produced with an average size of 200 nm. They displayed important cytotoxicity in a human lung cancer cells model (A549 cells), even at low concentrations, whereas free IONPs-Ac displayed adequate biocompatibility. Nevertheless, the treatment at the same concentration of ferri-liposomes against HEK-293 cells, a normal human cell lineage, was not significantly cytotoxic, revealing a probable lung tumor selectiveness of the fabricated formulation. Furthermore, from the flow cytometry studies, it was possible to infer that ferri-liposomes were able to induce A549 tumor cells death through apoptosis/ferroptosis processes, evidenced by a significant reduction of the mitochondrial membrane potential.

Synthesis of cholesterol-based neoglycoconjugates and their use in the preparation of liposomes for active liver targeting.

Carbohydrate receptors on liver represent attractive targets for receptor-mediated delivery of nanostructured therapeutics. In this study, two new cholesterol-based glycoconjugates derived from d-galactose and N-acetylglucosamine were synthesized and incorporated into liposomes. 99mTc-Cholesterol-DTPA complex was used for radiolabeling experiments in vivo with high radiochemical yields and stability. Biodistribution studies confirmed the targeting of galactosylated liposomes (GalL) to liver cells. These results indicated that GalL could be considered a promising drug delivery system for liver diseases therapy.

The role of radionuclide probes for monitoring anti-tumor drugs efficacy: A brief review.

Despite recent advances in the development of new therapeutic agents and diagnostic imaging modalities, cancer is still one of the main causes of death worldwide. A better understanding of the molecular signature of cancer has promoted the development of a new generation of anti-cancer drugs and diagnostic agents that specifically target molecular components such as genes, ligands, receptors and signaling pathways. However, intrinsic heterogeneity of tumors has hampered the overall success of target therapies even among patients with similar tumor types but unpredictable different responses to therapy. In this sense, post-treatment response monitoring becomes indispensable and nuclear medicine imaging modalities could provide the tools for an early indication of therapeutic efficacy. Herein, we briefly discuss the current role of PET and SPECT imaging in monitoring cancer therapy together with an update on the current radiolabeled probes that are currently investigated for tumor therapy response assessment.

Antiangiogenic activity of PLGA-Lupeol implants for potential intravitreal applications.

Uncontrolled angiogenesis is directly associated with ocular diseases such as macular degeneration and diabetic retinopathy. Implantable polymeric drug delivery systems have been proposed for intravitreal applications and in the present work, we evaluated the antiangiogenic potential of PLGA ocular implants loaded with the triterpene lupeol using in vitro and in vivo models. The drug/polymer physiochemical properties of the lupeol-loaded PLGA were validated as functionally similar using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Interestingly, in an in vitro culture system, lupeol (100µg/mL and 250µg/mL) was capable to inhibited the proliferation as well as the migration of Human Umbilical Vein Endothelial Cells (HUVEC), without interfering in cell viability, promoting a significant reduction in the percentage of vessels (39.41% and 44.12%, respectively), compared with the control group. In vivo test, by using the chorioallantoic membrane (CAM) model, lupeol-loaded PLGA ocular implants showed antiangiogenic activity comparable to the FDA-approved anti-VEGF antibody Bevacizumab. Overall, our results suggest lupeol-loaded PLGA ocular implants were able to inhibit the angiogenic process by impairing both proliferation and migration of endothelial cells.

Functionalized single-walled carbon nanotubes: cellular uptake, biodistribution and applications in drug delivery.

The unique properties of single-walled carbon nanotubes (SWNTs) enable them to play important roles in many fields. One of their functional roles is to transport cargo into cell. SWNTs are able to traverse amphipathic cell membranes due to their large surface area, flexible interactions with cargo, customizable dimensions, and surface chemistry. The cargoes delivered by SWNTs include peptides, proteins, nucleic acids, as well as drug molecules for therapeutic purpose. The drug delivery functions of SWNTs have been explored over the past decade. Many breakthrough studies have shown the high specificity and potency of functionalized SWNT-based drug delivery systems for the treatment of cancers and other diseases. In this review, we discuss different aspects of drug delivery by functionalized SWNT carriers, diving into the cellular uptake mechanisms, biodistribution of the delivery system, and safety concerns on degradation of the carriers. We emphasize the delivery of several common drugs to highlight the recent achievements of SWNT-based drug delivery.

Liposomes Containing Gadodiamide: Preparation, Physicochemical Characterization, and In Vitro Cytotoxic Evaluation.

BACKGROUND: The aim of this study was to develop, characterize and assess the cytotoxic activity of pHsensitive (pHL-Gd), stealth pH-sensitive (SpHL-Gd), and conventional (convL-Gd) liposomes containing gadodiamide (Gd-DTPA-BMA). METHODS: Formulations were prepared by reverse-phase evaporation method and their physicochemical properties were evaluated by means of particle size, zeta potential, and Gd-DTPA-BMA entrapment. SpHL-Gd was considered being the most promising liposome, since it combines stealth and fusogenic characteristics that might contribute to achieve higher therapeutic efficiency. Their drug encapsulation percentages have been optimized satisfactorily. The addition of Gd-DTPA-BMA at 125 µmol/mL in the SpHL-Gd preparation allowed obtaining liposomes with appropriate encapsulation percentage (20.3 ± 0.1%) and entrapment (25.4 ± 0.1 µmol/mL). RESULTS: The cytotoxic studies on the 4T1 breast cancer cell line demonstrated that liposomes-loaded with Gd-DTPA-BMA inhibited cancer cell. pHL-Gd and SpHL-Gd liposomes showed higher activity than convL-Gd and free Gd-DTPA-BMA, indicating that the pH-sensitive characteristic was important to improve intracellular delivery. CONCLUSION: The presence of polyethylene glycol (PEG) in the SpHL-Gd formulation did not affect the pH-sensitivity and internalization. Therefore, the results of this study suggest the feasibility of liposomes containing Gd-DTPA-BMA as a new promising controlled delivery system.

Boron nitride nanotubes coated with organic hydrophilic agents: stability and cytocompatibility studies.

In the present study, Boron Nitride Nanotubes (BNNTs) were synthesized and functionalized with organic hydrophilic agents constituted by glucosamine (GA), polyethylene glycol (PEG)1000, and chitosan (CH) forming new singular systems. Their size, distribution, and homogeneity were determined by photon correlation spectroscopy, while their surface charge was determined by laser Doppler anemometry. The morphology and structural organization were evaluated by Transmission Electron Microscopy. The functionalization was evaluated by Thermogravimetry analysis and Fourier Transformer Infrared Spectroscopy. The results showed that BNNTs were successfully obtained and functionalized, reaching a mean size and dispersity deemed adequate for in vitro studies. The in vitro stability tests also revealed a good adhesion of functionalized agents on BNNT surfaces. Finally, the in vitro cytocompatibility of functionalized BNNTs against MCR-5 cells was evaluated, and the results revealed that none of the different functionalization agents disturbed the propagation of normal cells up to the concentration of 50 µg/mL. Furthermore, in this concentration, no significantly chromosomal or morphologic alterations or increase in ROS (Reactive Oxygen Species) could be observed. Thus, findings from the present study reveal an important stability and cytocompatibility of functionalized BNNTs as new potential drugs or radioisotope nanocarriers to be applied in therapeutic procedures.

Long-circulating, pH-sensitive liposomes versus long-circulating, non-pH-sensitive liposomes as a delivery system for tumor identification.

Bombesin (BBN) is a tetradecapeptide that binds specifically to gastrin-releasing peptide receptors in humans. Several forms of cancer, including lung, prostate, breast, and colon over-express receptors for bombesin-like peptides. Therefore, radiolabeled bombesin analogs might be useful for tumor identification. Nevertheless, it is well known that higher tumor uptake can yield images in higher quality. Hence, drug delivery systems, such as liposomes, can be used to achieve a higher concentration of radiotracer in tumor site, and also improve the radiotracer stability, since peptides can suffer easily degradation in vivo by natural plasma and tissue peptides. In this paper, we prepared long-circulating, pH-sensitive liposomes and long-circulation, non-pH sensitive liposomes. Both formulations were able to encapsulate the radiolabeled bombesin derivative (99mTc-BBN(7_14)), and also showing high in vitro stability. Biodistribution studies were performed in Ehrlich tumor bearing-mice to compare the ability of pH-sensitive and non-pH sensitive liposomes to deliver 99mTc-BBN(7_14) to tumor site. Results showed higher tumor uptake (2-fold) when pH-sensitive liposomes were used, suggesting that these vesicles can facilitate the access to the tumor by releasing the diagnostic agent into the ideal area. As a result, tumor-to-muscle ratio achieved with pH-sensitive liposomes was higher than that obtained with non-pH-sensitive formulation. In addition, scintigraphic images for pH-sensitive liposomes showed evident tumor uptake, corroborating with biodistribution data. Therefore, the results presented in this paper suggest that pH-sensitive liposomes are able to deliver more efficiently the radiolabeled bombesin analog. This finding poses a new possibility to improve images quality, since the tumor-to-muscle ratio was strongly enhanced.

Antitumoral activity and toxicity of PEG-coated and PEG-folate-coated pH-sensitive liposomes containing ¹59Gd-DTPA-BMA in Ehrlich tumor bearing mice.

In the present study, PEG-coated pH-sensitive and PEG-folate-coated pH-sensitive liposomes containing the ¹59Gd-DTPA-BMA were prepared and radiolabeled through neutron activation technique, aiming to study the in vivo antitumoral activity and toxicity on mice bearing a previously-developed solid Ehrlich tumor. The treatment efficacy was verified through tumoral volume increase and histomorphometry studies. The toxicity of formulations was investigated through animal weight variations, as well as hematological and biochemical tests. The results showed that after 31 days of treatment, animals treated with radioactive formulations had a lower increase in tumor volume and a significantly higher percentage of necrosis compared with controls revealed by histomorphometry studies. Furthermore, mice treated with radioactive formulations exhibited lower weight gain without significant hematological or biochemical changes, except for toxicity to hepatocytes which requires more detailed studies. From the results obtained to date, we believe that the radioactive formulations can be considered potential therapeutic agents for cancer.

Boron nitride nanotubes radiolabeled with 99mTc: preparation, physicochemical characterization, biodistribution study, and scintigraphic imaging in Swiss mice.

In the present study, boron nitride nanotubes (BNNTs) were synthesized from an innovative process and functionalized with a glycol chitosan polymer in CDTN (Centro de Desenvolvimento da Tecnologia Nuclear) laboratories. As a means of studying their in vivo biodistribution behavior, these nanotubes were radiolabeled with (99m)Tc and injected in mice. Their size, distribution, and homogeneity were determined by photon correlation spectroscopy (PCS), while their zeta potential was determined by laser Doppler anemometry. The morphology and structural organization were evaluated by scanning electron microscopy (SEM). The functionalization in the nanotubes was evaluated by thermogravimetry analysis (TGA) and Fourier transformer infrared spectroscopy. The results showed that BNNTs were obtained and functionalized successfully, reaching a mean size and dispersity deemed adequate for in vivo studies. The BNNTs were also evaluated by ex vivo biodistribution studies and scintigraphic imaging in healthy mice. The results showed that nanostructures, after 24h, having accumulated in the liver, spleen and gut, and eliminated via renal excretion. The findings from this study reveal a potential application of functionalized BNNTs as new potential drugs or radioisotope nanocarriers to be applied in therapeutic procedures.

Tumor bombesin analog loaded long-circulating and pH-sensitive liposomes as tool for tumor identification.

Long-circulating and pH-sensitive liposomes trapping (99m)Tc-HYNIC-ßAla-bombesin((7-14)) (aSpHL-(99m)Tc-BBN((7-14))) were successfully prepared. Biodistribution studies and scintigraphic images were performed in Ehrlich tumor-bearing Swiss mice. This system showed high accumulation in tumor tissue with high tumor-to-muscle ratio. Therefore, aSpHL-(99m)Tc-BBN((7-14)) could be considered as a potential agent for tumor diagnosis.

Liposomes radiolabeled with (159)Gd: in vitro antitumoral activity, biodistribution study and scintigraphic image in Ehrlich tumor bearing mice.

PEG-coated pH-sensitive and PEG-folate-coated pH-sensitive liposomes containing the Gd-DTPA-BMA complex were prepared and radiolabeled by neutron activation. The radiolabeled liposomes presented significant in vitro cytotoxic activity against Ehrlich tumor cells when compared with controls. The biodistribution profile of these liposomes and free (159)Gd-DTPA-BMA were studied in mice bearing a previously-developed solid Ehrlich tumor. The results demonstrated an important uptake of the formulations by the tumor tissue, with a tissue/blood partition coefficient (Kp) 3.88 and 14.16 times higher than that of the free complex for pH-sensitive PEG-coated and PEG-folate-coated liposomes containing the (159)Gd-DTPA-BMA complex, respectively. Both formulations accumulated in the liver and spleen, thereby revealing some difficulty in escaping the action of the MPS cells. The formulation without folate presented a lower renal uptake, which is desirable in patients with chronic renal failure due to the potential risk of nephrogenic systemic fibrosis (NFS). The scintigraphic study revealed that the target/non-target ratio is always greater than three for pH-sensitive PEG-coated liposome formulations and above nine for pH-sensitive PEG-folate-coated liposome formulations. The results obtained in this study demonstrated that the formulations employed can be considered to be a potential alternative for the treatment of cancer, including patients with chronic renal failure.

Liposomes radiolabeled with 159Gd-DTPA-BMA: preparation, physicochemical characterization, release profile and in vitro cytotoxic evaluation.

The present work describes the preparation, labeling, physicochemical characterization, and in vitro cytotoxic evaluation of long circulating pH-sensitive liposomes containing (159)Gd-DTPA-BMA. These liposomes were successfully obtained and submitted to neutron irradiation for gadolinium labeling. Their size, distribution, and homogeneity were determined by photon correlation spectroscopy, while their zeta potential was determined by laser Doppler anemometry. The morphology and structural organization were evaluated by atomic force microscopy. The stability and release profiles of Gd-DTPA-BMA in the liposomes were determined in vitro in Dubelco's Modified Eagle's Medium and rat serum at 70%. The results showed that liposomes remained physically stable after 8 h of irradiation and presented a low release profile of its content in two different biological mediums. The formulation of liposomes containing (159)Gd and its respective controls were evaluated by in vitro cytotoxicity against tumor cells RT2. The results showed increased cytotoxic activity of approximately 1170 fold in relation to free Gd-DTPA-BMA.

Salvinia auriculata: aquatic bioindicator studied by instrumental neutron activation analysis (INAA).

Through instrumental neutron activation analysis (INAA) the elemental chemical composition of Salvinia auriculata and Ouro Preto city public water was determined. Elements Ce, Th, Cr, Hf, Sb, Sc, Rb, Fe, Zn, Co, Au, La and Br were quantified. High chromium concentration was determined in this plant. But, chromium was determined only in low concentrations in the water. The results indicate the great capacity of this plant to absorb and accumulate inorganic elements.