Enhanced contrast efficiency in MRI by PEGylated magnetoliposomes loaded with PEGylated SPION: effect of SPION coating and micro-environment

Rational design of magnetoliposomes for enhanced interaction with bacterial membrane models

There is a growing need for alternatives to target and treat bacterial infection. Thus, the present work aims to develop and optimize the production of PEGylated magnetoliposomes (MLPs@PEG), by encapsulating superparamagnetic iron oxide nanoparticles (SPIONs) within fusogenic liposomes. A Box-Behnken design was applied to modulate size distribution variables, using lipid concentration, SPIONs amount and ultrasonication time as independent variables. As a result of the optimization, it was possible to obtain MLPs@PEG with a mean size of 182 nm, with polydispersity index (PDI) of 0.19, and SPIONs encapsulation efficiency (%EE) around 76%. Cytocompatibility assays showed that no toxicity was observed in fibroblasts, for iron concentrations up to 400μg/ml. Also, for safe lipid and iron concentrations, no hemolytic effect was detected. The fusogenicity of the nanosystems was first evaluated through lipid mixing assays, based on Förster resonance energy transfer (FRET), using liposomal membrane models, mimicking bacterial cytoplasmic membrane and eukaryotic plasma membrane. It was shown that the hybrid nanosystems preferentially interact with the bacterial membrane model. Confocal microscopy and fluorescence lifetime measurements, using giant unilamellar vesicles (GUVs), validated these results. Overall, the developed hybrid nanosystem may represent an efficient drug delivery system with improved targetability for bacterial membrane.

Targeting to Brain Tumor: Nanocarrier-Based Drug Delivery Platforms, Opportunities, and Challenges

Cancer is a class of disorder characterized by anomalous growth of cells escalating in an uncontrolled way. Among all the cancers, treatment of cancerous brain tumors has been a tough challenge for the research scientists. Moreover, the absence of early-stage symptoms delays its diagnosis, consequently worsening its severity. Conventional treatments such as surgery, radiation, and chemotherapy are still linked with several limitations. The therapeutic effect of most of the anticancer drugs is highly restricted by their inability to pass the blood–brain barrier, low solubility, limited therapeutic window, and so on. Alarming incidences of brain cases associated with low survival rate across the globe coupled with the inefficiency of current treatment strategies have forced the formulation scientists to investigate nanotechnology-based advanced therapeutic approaches to tackle the disease. Various nanoplatforms such as polymeric nanoparticles (NPs), nanoliposomes, dendrimers, carbon nanotubes, and magnetic NPs have been reported in the past years to improve the drug administration into brain tumor cells and to minimize their off-target distribution for lesser side effects and better treatment outcomes. The review presents updated information on the nanocarrier-based drug delivery systems reported in the past few years for the treatment of brain tumor along with new advancements in this field. It also throws some light on the recent challenges faced in the practical field for the successful clinical translation of such nanodrug carriers along with a discussion on the future prospects.

One-step microfluidics production of enzyme-loaded liposomes for the treatment of inflammatory diseases

The biopharmaceuticals market is constantly growing. Despite their advantages over the conventional drugs, biopharmaceuticals have short biological half-lifes, which can be increased using liposomes. However, the common bulk methods to produce biopharmaceuticals-loaded liposomes result in lost of encapsulation efficiency (E.E.), resulting in an expensive process. Herein, the encapsulation of a therapeutic enzyme in liposomes is proposed, using a glass-capillary microfluidic technique. Cu,Zn- Superoxide dismutase (SOD) is successfully encapsulated into liposomes (SOD@Liposomes). SOD@Liposomes with a mean size of 135 ± 41 nm, a polydispersity index of 0.13 ± 0.01, an E.E. of 59 ± 6 % and an enzyme activity of 82 ± 3 % are obtained. in vivo experiments show, through an ear edema model, that SOD@Liposomes administered by the intravenous route enable an edema inhibition of 65 % ± 8 %, over the 20 % ± 13 % of SOD in its free form. The histopathological analyses show a higher inflammatory cell accumulation on the ear treated with SOD in its free form, than treated with SOD@Liposomes. Overall, this work highlights the potential of microfluidics for the production of enzyme-loaded liposomes with high encapsulation efficiency, with the intrinsic advantages of the low time-consuming and easily upscaling microfluidic assembly method.

Fabrication of Anisotropic Cu Ferrite-Polymer Core-Shell Nanoparticles for Photodynamic Ablation of Cervical Cancer Cells

In this work we developed methylene blue-immobilized copper-iron nanoparticles (MB-CuFe NPs) through a facile one-step hydrothermal reaction to achieve a better phototherapeutic effect. The Fe/Cu ratio of the CuFe NPs was controllable by merely changing the loading amount of iron precursor concentration. The CuFe NPs could serve as a Fenton catalyst to convert hydrogen peroxide (H2O2) into reactive oxygen species (ROS), while the superparamagnetic properties also suggest magnetic resonance imaging (MRI) potential. Furthermore, the Food and Drug Administration (FDA)-approved MB photosensitizer could strongly adsorb onto the surface of CuFe NPs to facilitate the drug delivery into cells and improve the photodynamic therapy at 660 nm via significant generation of singlet oxygen species, leading to enhanced cancer cell-damaging efficacy. An MTT (thiazolyl blue tetrazolium bromide) assay proved the low cytotoxicity of the CuFe NPs to cervical cancer cells (HeLa cells), namely above 80% at 25 ppm of the sample dose. A slight dissolution of Cu and Fe ions from the CuFe NPs in an acidic environment was obtained, providing direct evidence for CuFe NPs being degradable without the risk of long-term retention in the body. Moreover, the tremendous photo-to-thermal conversion of CuFe NPs was examined, which might be combined with photodynamic therapy (PDT) for promising development in the depletion of cancer cells after a single pulse of deep-red light irradiation at high laser power.

Folate encapsulation in PEG-diamine grafted mesoporous Fe3O4 nanoparticles for hyperthermia and in vitro assessment

Effective and targeted delivery of the antitumour drugs towards the specific cancer spot is the major motive of drug delivery. In this direction, suitably functionalised magnetic iron oxide nanoparticles (NPs) have been utilised as a theranostic agent for imaging, hyperthermia and drug delivery applications. Herein, the authors reported the preparation of multifunctional polyethyleneglycol-diamine functionalised mesoporous superparamagnetic iron oxide NPs (SPION) prepared by a facile solvothermal method for biomedical applications. To endow targeting ability towards tumour site, folic acid (FA) is attached to the amine groups which are present on the NPs surface by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride/N-hydroxysuccinimide chemistry. FA attached SPION shows good colloidal stability and possesses high drug-loading efficiency of ∼ 96% owing to its mesoporous nature and the electrostatic attachment of daunosamine (NH3+) group of doxorubicin (DOX) towards the negative surface charge of carboxyl and hydroxyl group. The NPs possess superior magnetic properties in result endowed with high hyperthermic ability under alternating magnetic field reaching the hyperthermic temperature of 43°C within 223 s at NP's concentration of 1 mg/ml. The functionalised NPs possess non-appreciable toxicity in breast cancer cells (MCF-7) which is triggered under DOX-loaded SPION.

Tailoring Iron Oxide Nanoparticles for Efficient Cellular Internalization and Endosomal Escape

Iron oxide nanoparticles (IONs) have been widely explored for biomedical applications due to their high biocompatibility, surface-coating versatility, and superparamagnetic properties. Upon exposure to an external magnetic field, IONs can be precisely directed to a region of interest and serve as exceptional delivery vehicles and cellular markers. However, the design of nanocarriers that achieve an efficient endocytic uptake, escape lysosomal degradation, and perform precise intracellular functions is still a challenge for their application in translational medicine. This review highlights several aspects that mediate the activation of the endosomal pathways, as well as the different properties that govern endosomal escape and nuclear transfection of magnetic IONs. In particular, we review a variety of ION surface modification alternatives that have emerged for facilitating their endocytic uptake and their timely escape from endosomes, with special emphasis on how these can be manipulated for the rational design of cell-penetrating vehicles. Moreover, additional modifications for enhancing nuclear transfection are also included in the design of therapeutic vehicles that must overcome this barrier. Understanding these mechanisms opens new perspectives in the strategic development of vehicles for cell tracking, cell imaging and the targeted intracellular delivery of drugs and gene therapy sequences and vectors.

In Vitro Assessment of Magnetic Liposomal Paclitaxel Nanoparticles as a Potential Carrier for the Treatment of Ovarian Cancer

Purpose: This study aimed to evaluate the role of magnetic liposome nanoparticles (ML NPs) as a carrier for paclitaxel (PTX) for the treatment of ovarian cancer in vitro.

Methods: Magnetic NPs (MNPs) were synthesized by chemical co-precipitation method. The resulting NPs were characterized in terms of size, size distribution, zeta potential, drug encapsulation efficiency (EE), drug release pattern, and cytotoxicity effects.

Results: The size and zeta potential of PTX-PEG-L and PTX-PEG-ML NPs were determined to be 296, 198 nm; -20, and -19 mV, respectively. Also, their drug encapsulation efficiencies were determined to be 97% and 96%, respectively. It was found that PTX-PEG-ML NPs, compared to PTX-PEG-L NPs, caused a reduction (11%) in the rate of drug release. The cytotoxicity of the drug-loaded NPs was assessed using 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay against human ovarian epithelial cancer (A2780CP) cells, and the results demonstrated that PTX-PEG-ML NPs caused higher cytotoxicity (by 14%) compared to PTX-PEG-L NPs (IC₅₀: 1.88 ± 0.09 and 2.142 ± 0.1 µM, respectively).

Conclusion: Overall, the results of this study suggest that PTX-PEG-ML NPs could be considered as a therapeutic candidate for the treatment of ovarian cancer.

Magneto-Liposomes as MRI Contrast Agents: A Systematic Study of Different Liposomal Formulations

The majority of the clinically approved iron oxide nanoparticles (IO NPs) used as contrast agents for magnetic resonance imaging (MRI) have been withdrawn from the market either due to safety concerns or lack of profits. To address this challenge, liposomes have been used to prepare IO-based T2 contrast agents. We studied the influence of different phospholipids on the relaxivity (r2) values of magneto-liposomes (MLs) containing magnetic NPs in the bilayer, where a strong correlation between the bilayer fluidity and r2 is clearly shown. Embedding 5-nm IO NPs in the lipid bilayer leads to a significant improvement in their relaxivity, where r2 values range from 153 ± 5 s-1 mM-1 for DPPC/cholesterol/DSPE-PEG (96/50/4) up to 673 ± 12 s-1 mM-1 for DOPC/DSPE-PEG (96/4), compared to "free" IO NPs with an r2 value of 16 s-1 mM-1, measured at 9.4 T MRI scanner. In vitro MRI measurements, together with the ICP-MS analysis, revealed MLs as highly selective contrast agents that were preferentially taken up by cancerous T24 cells, which led to an improvement in the contrast and an easier distinction between the healthy and the cancerous cells. A careful selection of the lipid bilayer to prepare MLs could offer efficient MRI contrast agents, even at very low IO NP concentrations.

A Review on the Optimal Design of Magnetic Nanoparticle-Based T2 MRI Contrast Agents

Relaxivity r2 and thus the contrast efficacy of superparamagnetic nanoparticles (NPs) can be enhanced via either NP’s magnetic properties or coating optimization. Numerous reports can be found about the investigation of the optimal iron oxide nanoparticles (IO NPs) size, shape, crystallinity and composition that yield high saturation magnetization (ms) values and, consequently, high r2 values. Although the use of an appropriate coating can boost up the NPs MRI contrast agent efficiency, this topic has been largely understudied. Therefore, in this review, the factors affording r2 enhancement of spherical magnetic NPs are discussed. Based on the literature, the requirements for an optimal surface coating that may increase r2 values and ensure stability and biocompatibility of NPs are listed. One of the best candidates that fulfil these requirements are liposomes with embedded magnetic NPs, so-called magneto-liposomes. The analysis of the literature elucidated the most appropriate phospholipid compositions for the relaxivity enhancement and for magneto-liposomes in vivo stability. Finally, the future directions in the development of NP-based contrast agents are given. For example, most of the synthetic NPs are recognized and eliminated as a foreign substance by the immune system. To overcome this issue, a design of a biomimetic, cell-membrane-based nanocarrier for contrast agents is proposed. Disguised with cell membranes, NPs or other active components can act as autogenous cells and thus ensure the inherent biocompatibility.

Magnetic field-assisted selective delivery of doxorubicin to cancer cells using magnetoliposomes as drug nanocarriers

Magnetoliposomes are promising candidates for the development of selective drug delivery systems in the treatment of cancer. Those nanosystems were tested as carriers of a strong chemotherapeutic agent, doxorubicin, which is used against breast cancer. Herein, the magnetic properties of hydrophobic iron oxide nanoparticles located exclusively in the lipid bilayer were used to release this drug from the magnetoliposomes. The cytotoxic activity of the nanostructures against the normal and cancer cell lines was determined on the basis of cells viability measurement after incubation with different concentrations of these nanomaterials. In the same way, the effectiveness of killing cancer cells in combination with exposure to magnetic field was also evaluated. These experiments confirmed that the nanostructures composed of liposomes and magnetic nanoparticles are not cytotoxic. However, magnetoliposomes loaded with doxorubicin were effective and selective in reducing the viability of human breast tumor cell lines. In this paper, we demonstrated the promising application of the studied magnetoliposomes as carriers of doxorubicin released under the influence of magnetic field in tumor cells.

Neurotheranostics as personalized medicines

The discipline of neurotheranostics was forged to improve diagnostic and therapeutic clinical outcomes for neurological disorders. Research was facilitated, in largest measure, by the creation of pharmacologically effective multimodal pharmaceutical formulations. Deployment of neurotheranostic agents could revolutionize staging and improve nervous system disease therapeutic outcomes. However, obstacles in formulation design, drug loading and payload delivery still remain. These will certainly be aided by multidisciplinary basic research and clinical teams with pharmacology, nanotechnology, neuroscience and pharmaceutic expertise. When successful the end results will provide "optimal" therapeutic delivery platforms. The current report reviews an extensive body of knowledge of the natural history, epidemiology, pathogenesis and therapeutics of neurologic disease with an eye on how, when and under what circumstances neurotheranostics will soon be used as personalized medicines for a broad range of neurodegenerative, neuroinflammatory and neuroinfectious diseases.

Formulation and in vitro evaluation of a siRNA delivery nanosystem decorated with gH625 peptide for triple negative breast cancer theranosis

The development of an efficient small interfering RNA (siRNA) delivery system has held scientists interest since the discovery of the RNA interference mechanism (RNAi). This strategy gives hope for the treatment of many severe diseases. Herein, we developed hybrid nanovectors able to deliver siRNA to triple negative breast cancer cells. The nanovectors are based on PEGylated superparamagnetic iron oxide nanoparticles (SPION) functionalized with gH625 peptide, chitosan and poly-l-arginine. Every component has a key role and specific function: SPION is the core scaffolding the nanovector; PEG participates in the colloidal stability and the immune stealthiness; gH625 peptide promotes the nanovector internalization into cancer cells; cationic polymers provide the siRNA protection and favor siRNA endosomal escape and delivery to cytosol. The formulation was optimized by varying the amount of each compound. The efficacy of the siRNA retention and protection were investigated in the presence of high concentration of serum. Optimized nanovectors show a high uptake by MDA-MB-231 cells. The resulting down regulation of GFP expression was 73 ± 3% with our nanovector compared to 59 ± 8% obtained with the siRNA-Oligofectamine™ complex in the same conditions.

Theranostic imaging of liver cancer using targeted optical/MRI dual-modal probes

The accurate preoperative detection and intraoperative navigation afforded by imaging techniques have had significant impact on the success of liver cancer surgeries. However, it is difficult to achieve satisfactory performance in both diagnosis and surgical treatment processes using any single modality imaging method. Here, we report the synthesis and characteristics of a novel dual-modality magnetic resonance imaging (MRI) and near-infrared fluorescence (NIRF) probe and verify its feasibility in nude mouse models with liver cancer. The probes are comprised of superparamagnetic iron oxide (SPIO) nanoparticles coated with liposomes to which a tumor-targeted agent, Arg-Gly-Asp peptides (RGD), and a NIRF dye (indocyanine green, ICG) have been conjugated. Specific targeting, biodistribution, and the imaging ability of the probes for MRI-NIRF were examined. Furthermore, we applied the dual-modality methodology toward the preoperative diagnosis and intraoperative guidance of radical resection in mouse models with both orthotopic liver tumors and intrahepatic tumor metastasis. The study demonstrated that both MRI and fluorescent images showed clear tumor delineation after probe injection (SPIO@Liposome-ICG-RGD). The contrast-to-noise ratio obtained from MRI was 31.9 ± 25.4 at post-injection for the preoperative diagnosis, which is helpful for detecting small tumors (0.9 ± 0.5 mm). The maximum tumor to background ratio of NIRF imaging was 2.5 ± 0.3 at 72 h post-injection for effectively capturing miniscule tumor lesions (0.6 ± 0.3 mm) intraoperatively. The novel MRI-NIRF dual modality probes are promising for the achievement of more accurate liver tumor detection and resection.

Development of New Contrast Agents for Imaging Function and Metabolism by Magnetic Resonance Imaging

Liposomes are interesting nanosystems with a wide range of medical application. One particular application is their ability to enhance contrast in magnetic resonance images; when properly loaded with magnetic/superparamagnetic nanoparticles, this means to act as contrast agents. The design of liposomes loaded with magnetic particles, magnetoliposomes, presents a large number of possibilities depending on the application from image function to metabolism. More interesting is its double function application as theranostics (diagnostics and therapy). The synthesis, characterization, and possible medical applications of two types of magnetoliposomes are reviewed. Their performance will be compared, in particular, their efficiency as contrast agents for magnetic resonance imaging, measured by their relaxivities r₁ and r₂ relating to their particular composition. One of the magnetoliposomes had 1,2-diacyl-sn-glycero-3-phosphocholine (soy) as the main phospholipid component, with and without cholesterol, varying its phospholipid to cholesterol molar ratios. The other formulation is a long-circulating liposome composed of 1,2-diacyl-sn-glycero-3-phosphocholine (egg), cholesterol, and 1,2-distearoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000]. Both nanosystems were loaded with superparamagnetic iron oxide nanoparticles with different sizes and coatings.

Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes

Superparamagnetic iron oxide nanoparticles (SPIONs) with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to bê11 nm), silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm). Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a slightly increased effect on the fluidity of the model membranes in comparison with the incubated SPIONs. This indicates the low potential of the SPIONs to interact with the nontargeted cell membranes, which is a desirable factor for in vivo applications.

Aptamer-Modified Temperature-Sensitive Liposomal Contrast Agent for Magnetic Resonance Imaging

A novel aptamer modified thermosensitive liposome was designed as an efficient magnetic resonance imaging probe. In this paper, Gd-DTPA was encapsulated into an optimized thermosensitive liposome (TSL) formulation, followed by conjugation with AS1411 for specific targeting against tumor cells that overexpress nucleolin receptors. The resulting liposomes were extensively characterized in vitro as a contrast agent. As-prepared TSLs-AS1411 had a diameter about 136.1 nm. No obvious cytotoxicity was observed from MTT assay, which illustrated that the liposomes exhibited excellent biocompatibility. Compared to the control incubation at 37 °C, the liposomes modified with AS1411 exhibited much higher T1 relaxivity in MCF-7 cells incubated at 42 °C. These data indicate that the Gd-encapsulated TSLs-AS1411 may be a promising tool in early cancer diagnosis.

Central nervous system toxicity of metallic nanoparticles

Nanomaterials (NMs) are increasingly used for the therapy, diagnosis, and monitoring of disease- or drug-induced mechanisms in the human biological system. In view of their small size, after certain modifications, NMs have the capacity to bypass or cross the blood–brain barrier. Nanotechnology is particularly advantageous in the field of neurology. Examples may include the utilization of nanoparticle (NP)-based drug carriers to readily cross the blood–brain barrier to treat central nervous system (CNS) diseases, nanoscaffolds for axonal regeneration, nanoelectromechanical systems in neurological operations, and NPs in molecular imaging and CNS imaging. However, NPs can also be potentially hazardous to the CNS in terms of nano-neurotoxicity via several possible mechanisms, such as oxidative stress, autophagy, and lysosome dysfunction, and the activation of certain signaling pathways. In this review, we discuss the dual effect of NMs on the CNS and the mechanisms involved. The limitations of the current research are also discussed.