Emilio Squillante

The formulation, characterization and in vivo evaluation of a magnetic carrier for brain delivery of NIR dye

This work reports the targeting of the near infrared (NIR) dye indocyanine green (ICG) to the brain using composite nanoparticles. Thermal decomposition of iron pentacarbonyl was used to synthesize monodisperse oleic acid coated magnetic nanoparticles (OAMNP). Synthesized OAMNP and ICG were encapsulated in a poly (lactide-co-glycolide) matrix using an emulsion evaporation method. Different batches containing OAMNP:PLGA ratios (1:4, 1:2 and 3:4) were prepared with ICG (group B-1, 2, 3) and without ICG (group A-1, 2, 3) loading. All the formulations were characterized in terms of morphology, particle size, zeta potential, magnetic content, ICG encapsulation efficiency and the spectral properties of ICG. The optimized formulation showed an encapsulation efficiency of 56 +/- 4.6% for ICG and 57 +/- 1.37% for OAMNP. The biodistribution and brain targeting study involved three groups of six animals, each with 0.4 mg kg(-1) equivalent of ICG, given as neat ICG solution, composite nanoparticles without the aid of a magnetic field, and composite nanoparticles under the influence of a magnetic field (8000 G) to groups 1, 2 and 3 respectively. The tissue analysis and microscopy images revealed a significantly higher brain concentration of ICG (p < 0.05) for group 3 than the two control groups. These results are encouraging for the brain delivery of hydrophilic dyes/drugs using this method for biomedical applications.

Applications of Fiber-Optic Evanescent Wave Spectroscopy

The evanescent wave (EW) component of light propagated via fiber-optic wave-guides can be used to both sense and transmit information regarding the immediate environment of the fibers surface. In this article, an outline of the theoretical and practical aspects of this emerging methodology is given, as well as a discussion of the advantages, disadvantages, and limitations of the technique. Examples are given of how EW spectroscopy may be used in the analysis of pharmaceutical systems. Evaluation of attributes of components of EW spectroscopy allows prediction of the future for this rapidly evolving area of photonics.

Revisiting the role of nanoparticles as modulators of drug resistance and metabolism in cancer

ABSTRACT Introduction: Drug resistance is the major obstacle impeding the efficacy of chemotherapeutic agents. Although numerous drug delivery techniques have been developed to combat drug resistance, their limitations of non-specific targeting and inconsistent bioavailability has led to the search of novel delivering strategies, such as nanoparticles. Areas covered: Nanoparticles for anti-cancer drug delivery are microscopic preparations encapsulating a chemotherapeutic and a chemosensitizer into a rationally designed drug delivery vehicle. Nano-strategies directed against multi-drug resistance (MDR) can be categorized into those inhibiting the drug efflux pumps, those effective against the cellular factors of drug resistance, and the combinational based strategies. Here, we review the most recent literature to reposition nanoparticles as chemotherapeutics and inhibitors of MDR. Expert Opinion: Novelty in anti-cancer drug delivery has led to the formulation of chemotherapeutics and MDR inhibitors as nano-preparations, which are multi-functional and have better tumor cell-targeting effects. Their characteristics of size and surface attachments make them readily diffusible through the tumor vasculature and increase their retention time as well. With a better understanding of the molecular mechanisms of drug resistance, more potent and multi-targeted nano-preparations can be formulated in the near future.

In vivo brain microdialysis to evaluate FITC-dextran encapsulated immunopegylated nanoparticles

Context: Delivery of drugs and dyes through intact blood–brain barrier (BBB) is extremely sought-after. A safe and reliable measurement of delivery efficacy in live animals is necessary. Objective: To investigate the brain uptake of FITC-dextran MW 4000 (FD4) by CD71/OX-26 coated nanoparticles by microdialysis sampling and fluorescence/confocal microscopy. Materials and methods: Methoxy-poly(ethylene glycol)-poly(lactide) (Met-PEG-PLA) and maleimide-poly(ethylene glycol)-poly(lactide) (Mal-PEG-PLA) nanoparticles were prepared by nanoprecipitation. The surfaces of the prepared nanoparticles were embellished with CD-71/OX-26 antibodies for brain targeting. Male Sprague Dawley rats received 0.4 mg/kg FD4 and equivalent nanoparticulate formulation through lateral tail vein. Animals were euthanized 24 h postadministration, after which the tissues were harvested and analyzed for FD4 concentrations. Tissues were fixed with paraformaldehyde, cryotomed to 20 µm sections, and analyzed by Total Internal Reflection microscopy. Results: Particle sizes of 200 ± 25 nm and zeta potentials of −18 ± 1 mV were obtained. FD4 concentrations, determined using in vivo brain microdialysis, were high on the first day (~360 ng/mL) compared to 60 ng/mL on the following 2 days. The nanoparticle treated animals showed significantly higher (p < 0.05) FD4 concentrations in the brain than pure-FD4 treated animals. Immunopegylated nanoparticles sustained and enhanced Central nervous system (CNS) concentration of hydrophilic dye for at least 3 days. Conclusion: Immunopegylated nanoparticles produce enhanced and sustained uptake of brain permeability marker FD4 relative to controls.

In vivo brain microdialysis as a formulation-screening tool for a poorly soluble centrally acting drug

Abstract Objective: Efficacy of a formulation of a poorly soluble centrally acting drug was evaluated by measuring dopamine responses using in vivo brain microdialysis. Methods: Co-crystals (1:1) of carbamazepine and nicotinamide (CBZ–NCT) were complexed with cyclodextrins (γ-CDs) using supercritical fluid processing. Phase solubility and intrinsic dissolution were studied. Pharmacodynamic studies were performed on rats divided into three groups getting either CBZ–NCT in CD (20 mg/kg CBZ), pure CBZ solution or vehicle. A guide cannula was implanted to attach the microdialysis probe. Dialysate samples were analyzed for dopamine levels, which were compared between groups. Results: The optimized CBZ formulation (5% w/w in γ-CD) with solubility – 10 mg/mL showed stepwise increase in dopamine response (maximum 250% of baseline) compared to neat CBZ or vehicle (p < 0.05). The pharmacokinetics of the drug required 30 min to elicit CNS response, which peaked at about 1.5–2 h. Conclusion: Hence, brain microdialysis was successfully used to evaluate a dissolution rate enhancing formulation.

Targeted polymeric magnetic nanoparticles for brain imaging

The purpose of this study was to develop targeted polymeric magnetic nanoparticle system for brain imaging. Near infrared dye indocyanine green (ICG) or p-gycoprotein substrate rhodamine 123 (Rh123) were encapsulated along with oleic acid coated magnetic nanoparticles (OAMNP) in a matrix of poly(lactide-co-glycolide) (PLGA) and methoxy poly(ethyleneglycol)-poly(lactide) (Met-PEG-PLA). The nanoparticles were evaluated for morphology, particle size, dye content and magnetite content. The in vivo biodistribution study was carried out using three groups of six male Sprague Dawley rats each. Group I received a saline solution containing the dye, group II received dye-loaded polymeric magnetic nanoparticles without the aid of a magnetic field, and group III received dye-loaded polymeric magnetic nanoparticles with a magnet (8000 G) placed on the head of the rat. After a preset exposure period, the animals were sacrificed and dye concentration was measured in the brain, liver, kidney, lungs and spleen homogenates. Brain sections were fixed, cryotomed and visualized using fluorescence microscopy. The particles were observed to be spherical and had a mean size of 220 nm. The encapsulation efficiency for OAMNP was 57%, while that for ICG was 56% and for Rh123 was 45%. In the biodistribution study, while the majority of the dose for all animals was found in the liver, kidneys and spleen, group III showed a significantly higher brain concentration than the other two groups (p < 0.001). This result was corroborated by the fluorescence microscopy studies, which showed enhanced dye penetration into the brain tissue for group III. Further studies need to be done to elucidate the exact mechanism responsible for the increased brain uptake of dye to help us understand if the magnetic nanoparticles actually penetrate the blood brain barrier or merely deliver a massive load of dye just outside it, thereby triggering passive diffusion into the brain parenchyma. These results reinforce the potential use of polymeric magnetically-targeted nanoparticles in active brain targeting and imaging.