The Development of Drug-Free Therapy for Prevention of Dental Caries

Purpose

The purpose of this study was to develop a novel, drug-free therapy that can reduce the over-accumulation of cariogenic bacteria on dental surfaces.

Methods

We designed and synthesized a polyethylene glycol (PEG)-based hydrophilic copolymer functionalized with a pyrophosphate (PPi) tooth-binding anchor using “click” chemistry. The polymer was then evaluated for hydroxyapatite (HA) binding kinetics and capability of reducing bacteria adhesion to artificial tooth surface.

Results

The PPi-PEG copolymer can effectively inhibit salivary protein adsorption after rapid binding to an artificial tooth surface. As a result, the in vitro S. mutans adhesion study showed that the PPi-PEG copolymer can inhibit saliva protein-promoted S. mutans adhesion through the creation of a neutral, hydrophilic layer on the artificial tooth surface.

Conclusions

The results suggested the potential application of a PPi-PEG copolymer as a drug-free alternative to current antimicrobial therapy for caries prevention.     

Behavioral inhibition in mice bred for high vs. low levels of methamphetamine consumption or sensitization

Rationale

Research indicates that genetics influence methamphetamine self-administration as well as sensitization to the psychomotor-stimulating effects of methamphetamine (MA). Other studies have suggested that heightened levels of impulsivity, including low levels of behavioral inhibition, are associated with the use of drugs, including MA.

Objectives

The current study examined whether lines of mice selected for traits associated with a heightened risk of developing MA dependence would also exhibit low levels of drug-na?ve inhibition and whether administration of MA would result in different levels of inhibition in animals selected to consume or respond more to MA.

Methods

A go/no-go task was used to assess inhibition in male and female mice selected for low or high levels of MA consumption or selected for high or low levels of locomotor sensitization to repeated injections of MA.

Results

Mice selected for MA sensitization differed in false alarms, precue response rates (measures of behavioral inhibition), and also hits (measure of operant responding). Mice selected for MA consumption did not differ in measures of behavioral inhibition, though hits differed. When MA was administered prior to the task, false alarms, precue response rates, and hits decreased for mice from all selected lines. Female high drinking mice were particularly resistant to MA??s effects on hits, but not precue response rate or false alarms.

Conclusions

These data suggest a shared, but complex, genetic association between inhibition processes, general levels of operant responding, and MA sensitization or consumption.     

Modulating Sticking Propensity of Pharmaceuticals Through Excipient Selection in a Direct Compression Tablet Formulation

Purpose

To investigate how excipient matrix affects punch sticking propensity of active pharmaceutical ingredients (API), with the focus on the effect of bonding interactions between API-API (F2) and API-excipient (F3).

Method

Sticking kinetics of direct compression formulations, consisting of 20% of celecoxib (CEL) or ibuprofen (IBN) in different excipient matrices, i.e., microcrystalline cellulose (Avicel PH102 and Avicel PH105 dry coated with nano-sized silica (PH105(n)), hypromellose (K15 M), and a 3:1 mixture between starch and Avicel PH102 (S3P1), was assessed using a removable punch tip on a compaction simulator. The amount of material transferred to punch was determined gravimetrically every 10 compressions up to 50 compactions.

Results

CEL exhibited higher F2 than IBN. CEL also exhibited more sticking under otherwise identical compaction conditions in the same excipient matrix. Among different excipient matrices, sticking propensity of both APIs followed the ascending order: PH105(n)?<?PH102?<?K15 M?<?S3P1. This order was exactly opposite to the order of F3, confirming that greater bonding strength of the formulation favors lower sticking propensity of a given API.

Conclusion

For an API prone to punch sticking, judicious use of excipients to render higher tablet mechanical strength can mitigate severity of punch sticking.

     

Modeling of adhesion in tablet compression--I. Atomic force microscopy and molecular simulation

Adhesion problems during tablet manufacturing have been observed to be dependent on many formulation and process factors including the run time on the tablet press. Consequently, problems due to sticking may only become apparent towards the end of the development process when a prolonged run on the tablet press is attempted for the first time. It would be beneficial to predict in a relative sense if a formulation or new chemical entity has the potential for adhesion problems early in the development process. It was hypothesized that favorable intermolecular interaction between the drug molecules and the punch face is the first step or criterion in the adhesion process. Therefore, the rank order of adhesion during tablet compression should follow the rank order of these energies of interaction. The adhesion phenomenon was investigated using molecular simulations and contact mode atomic force microscopy (AFM). Three model compounds were chosen from a family of "profen" compounds. Silicon nitride AFM tips were modified by coating a 20-nm iron layer on the surfaces by sputter coating. Profen flat surfaces were made by melting and recrystallization. The modified AFM probe and each profen surface were immersed in the corresponding profen saturated water during force measurements using AFM. The work of adhesion between iron and ibuprofen, ketoprofen, and flurbiprofen in vacuum were determined to be -184.1, -2469.3, -17.3 mJ. m(-2), respectively. The rank order of the work of adhesion between iron and profen compounds decreased in the order: ketoprofen > ibuprofen > flurbiprofen. The rank order of interaction between the drug molecules and the iron superlattice as predicted by molecular simulation using Cerius(2) is in agreement with the AFM measurements. It has been demonstrated that Atomic Force Microscopy is a powerful tool in studying the adhesion phenomena between organic drug compounds and metal surface. The study has provided insight into the adhesion problems occurring during tablet compression and a direction for continued study.     

Erythropoietin-Coated ZP-Microneedle Transdermal System: Preclinical Formulation, Stability, and Delivery

Purpose

To evaluate the feasibility of coating formulated recombinant human erythropoietin alfa (EPO) on a titanium microneedle transdermal delivery system, ZP-EPO, and assess preclinical patch delivery performance.

Methods

Formulation rheology and surface activity were assessed by viscometry and contact angle measurement. EPO liquid formulation was coated onto titanium microneedles by dip-coating and drying. Stability of coated EPO was assessed by SEC-HPLC, CZE and potency assay. Preclinical in vivo delivery and pharmacokinetic studies were conducted in rats with EPO-coated microneedle patches and compared to subcutaneous EPO injection.

Results

Studies demonstrated successful EPO formulation development and coating on microneedle arrays. ZP-EPO patch was stable at 25°C for at least 3?months with no significant change in % aggregates, isoforms, or potency. Preclinical studies in rats showed the ZP-EPO microneedle patches, coated with 750?IU to 22,000?IU, delivered with high efficiency (75?C90%) with a linear dose response. PK profile was similar to subcutaneous injection of commercial EPO.

Conclusions

Results suggest transdermal microneedle patch delivery of EPO is feasible and may offer an efficient, dose-adjustable, patient-friendly alternative to current intravenous or subcutaneous routes of administration.     

Rapid Assessment of Homogeneity and Stability of Amorphous Solid Dispersions by Atomic Force Microscopy—From Bench to Batch

Purpose

To verify the robustness and fundamental value of Atomic Force Microscopy (AFM) and AFM-based assays to rapidly examine the molecular homogeneity and physical stability of amorphous solid dispersions on Hot-Melt-Extrudates.

Methods

Amorphous solid dispersions were prepared with a Hot-Melt Extruder (HME) and profiled by Raman Microscopy and AFM following a sequential analytical routine (Multi-Scale-Imaging-of-Miscibiliy (MIMix)). Extrudates were analyzed before and after incubation at elevated temperature and humidity. The data were compared with published results as collected on miniaturized melt models. The value of molecular phase separation rates for long term stability prediction was assessed.

Results

Data recorded on the extrudates are consistent with those published, and they can be compared side by side. Such direct data comparisons allow the identification of possible sources of extrudate heterogeneities. The surface roughness analysis of fracture-exposed interfaces is a novel quantitative way to trace on the nanometer scale the efficiencies of differently conducted HME-processes. Molecular phase separation rates are shown to be relevant for long term stability predictions.

Conclusions

The AFM-based assessment of API:excipient combinations is a robust method to rapidly identify miscible and stable solid dispersions in a routine manner. It provides a novel analytical tool for the optimization of HME processes.     

Decreasing Herpes Simplex Viral Infectivity in Solution by Surface-Immobilized and Suspended N,N-Dodecyl,methyl-polyethylenimine

Purpose

To explore surface-immobilized and suspended modalities of the hydrophobic polycation N,N-dodecyl,methyl-polyethylenimine (DMPEI) for the ability to reduce viral infectivity in aqueous solutions containing herpes simplex viruses (HSVs) 1 and 2.

Methods

Surface-immobilized (coated onto surfaces) and suspended DMPEI were incubated with aqueous solutions containing HSV-1 or -2 to measure the antiviral effect of the hydrophobic polycation??s formulations on HSVs.

Results

DMPEI coated on either polyethylene slides or male latex condoms dramatically decreases infectivity in solutions containing HSV-1 or -2. Moreover, DMPEI suspended in aqueous solution markedly reduces the infectious titer of these HSVs.

Conclusion

Our results suggest potential uses of DMPEI for both prophylaxis (in the form of coated condoms) and treatment (as a topical suspension) for HSV infections.     

A Magnetic Nanoparticle Stabilized Gas Containing Emulsion for Multimodal Imaging and Triggered Drug Release

Purpose

To develop a multimodal imaging guided and triggered drug delivery system based on a novel emulsion formulation composed of iron oxide nanoparticles, nanoscopic bubbles, and oil containing drugs.

Methods

Iron oxide paramagnetic nanoparticles were synthesized and modified with surface conjugation of polyethylenimide (PEI) or Bovine Serum Albumin (BSA). Both particles were used to disperse and stabilize oil in water emulsions containing coumarin-6 as the model drug. Sulfur hexafluoride was introduced into the oil phase to form nanoscopic bubbles inside the emulsions. The resulted gas containing emulsions were evaluated for their magnetic resonance (MR) and ultrasound (US) imaging properties. The drug release profile triggered by ultrasound was also examined.

Results

We have successfully prepared the highly integrated multi-component emulsion system using the surface modified iron oxide nanoparticles to stabilize the interfaces. The resulted structure had distinctive MR and US imaging properties. Upon application of ultrasound waves, the gas containing emulsion would burst and encapsulated drug could be released.

Conclusion

The integrated emulsion formulation was multifunctional with paramagnetic, sono-responsive and drug-carrying characteristics, which may have potential applications for disease diagnosis and imaging guided drug release.     

Specific Binding,Uptake, and Transport of ICAM-1-Targeted Nanocarriers Across Endothelial and Subendothelial Cell Components of the Blood–Brain Barrier

Purpose

The blood–brain barrier (BBB) represents a target for therapeutic intervention and an obstacle for brain drug delivery. Targeting endocytic receptors on brain endothelial cells (ECs) helps transport drugs and carriers into and across this barrier. While most receptors tested are associated with clathrin-mediated pathways, clathrin-independent routes are rather unexplored. We have examined the potential for one of these pathways, cell adhesion molecule (CAM)-mediated endocytosis induced by targeting intercellular adhesion molecule -1 (ICAM-1), to transport drug carriers into and across BBB models.

Methods

Model polymer nanocarriers (NCs) coated with control IgG or antibodies against ICAM-1 (IgG NCs vs. anti-ICAM NCs; ~250-nm) were incubated with human brain ECs, astrocytes (ACs), or pericytes (PCs) grown as monocultures or bilayered (endothelial+subendothelial) co-cultures.

Results

ICAM-1 was present and overexpressed in disease-like conditions on ECs and, at a lesser extent, on ACs and PCs which are BBB subendothelial components. Specific targeting and CAM-mediated uptake of anti-ICAM NCs occurred in these cells, although this was greater for ECs. Anti-ICAM NCs were transported across endothelial monolayers and endothelial+subendothelial co-cultures modeling the BBB.

Conclusions

CAM-mediated transport induced by ICAM-1 targeting operates in endothelial and subendothelial cellular components of the BBB, which may provide an avenue to overcome this barrier.     

Biocompatible Glycol Chitosan-Coated Gold Nanoparticles for Tumor-Targeting CT Imaging

Purpose

The application of gold nanoparticles (AuNPs) in biomedical field was limited due to the low stability in the biological condition. Herein, to enhance stability and tumor targeting ability of AuNPs, their surface was modified with biocompatible glycol chitosan (GC) and the in vivo biodistribution of GC coated AuNPs (GC-AuNPs) were studied through computed tomography (CT).

Methods

Polymer-coated gold nanoparticles were produced using GC as a reducing agent and a stabilizer. Their feasibility in biomedical application was explored through CT in tumor-bearing mice.

Results

Stability of gold nanoparticles increased in the physiological condition due to the GC coating layer on the surface. Tomographic images of tumor were successfully obtained in the tumor-xenografted animal model when the GC-AuNPs were used as a CT contrast agent. The tumor targeting property of the gold nanoparticles was due to the properties of GC because GC-AuNPs were accumulated in the tumor, while most of heparin-coated nanoparticles were found in the liver and spleen.

Conclusions

The polymer properties on the surface played an important role in the behavior of gold nanoparticles in the biological condition and the enhanced stability and tumor targeting property of nanoparticles were inherited from GC on the surface.     

Fluorogenic Tagging Methodology Applied to Characterize Oxidized Tyrosine and Phenylalanine in an Immunoglobulin Monoclonal Antibody

Purpose

Metal-catalyzed oxidation (MCO) of proteins is of primary concern in the development of biotherapeutics as it represents a prominent degradation pathway with potential undesired biological and biotherapeutic consequences.

Methods

We developed a fluorogenic derivatization methodology to study the MCO of IgG1 using a model oxidation system, CuCl₂/L-ascorbic acid.

Results

Besides the oxidation of Met, Trp and His residues, we detected significant oxidation of Phe and Tyr in IgG1.

Conclusion

The fluorogenic derivatization method provides an alternative approach for the rapid detection of oxidized Tyr and Phe as their benzoxazole derivatives by fluorescence spectrometry and size exclusion chromatography coupled to fluorescence detection.     

Evaluation of Coating Properties of Enteric-Coated Tablets Using Terahertz Pulsed Imaging

Purpose

Enteric coatings are used to reduce gastrointestinal side effects and control the release properties of oral medications. Although widely used, the effect of formulation and process conditions on physicochemical and functional properties of enteric coatings remains unclear.

Methods

Terahertz pulsed imaging (TPI) was employed to evaluate the coat properties of enteric coated tablets (ECTs) with various acid resistance. Other analytic methods, such as loss on drying, scanning electron microscopy and X-ray computed tomography were then used to validate the relationships established among 4 TPI-derived parameters and the physicochemical properties of enteric coatings.

Results

Weight gain measurement did not provide any information to assess acid resistance of enteric coating, whereas four TPI-derived parameters non-destructively reflected the coating properties such as thickness, coat uniformity, density, and water distribution, allowing the identification of the causes of poor acid resistance in certain ECT batches using a single measurement. These parameters also revealed the effect of coating conditions; in particular, coating under dry conditions led to less dense and nonuniform coatings with poor acid resistance.

Conclusion

We demonstrated the utility of TPI to identify structural defects within ECTs with poor acid resistance. TPI-derived parameters can aid in formulation development and quality control of ECTs.     

Preparation and Evaluation of Palm Oil-Based Polyesteramide Solid Dispersion for Obtaining Improved and Targeted Dissolution of Mefenamic Acid

Purpose

The aim of this work was to investigate the functional role of newly synthesised palm oil-based polyesteramide (POPEA) and stearic acid-based polyesteramide (SAPEA) in mefenamic acid (MA) solid dispersion (SD).

Methods

Solid dispersions of MA were prepared by hot melt method, using a combination of POPEA/SAPEA as a polymer carrier. The effects of POPEA/SAPEA mixture ratio, drug loading percentage and influence of different Mw of POPEA (4000–17,000 Da) in SD were investigated. The SDs were characterised for drug content, solubility, dissolution behaviour and physico-chemical characteristics by DSC and FTIR. Comparisons were made with pure drug, physical mixture and a marketed MA formulation.

Results

All SDs demonstrated faster dissolution rate than pure MA and SD 6 formulated with SAPEA/POPEA 4000 Da, 8:2 showed the highest T ₅₀ release rate (45 min) with no significant difference (P?>?0.05) compared to marketed formulation. All SDs showed improved drug release (85.48?±?1.17 to 90.66?±?1.53%) against marketed formulation (81.30?±?1.26%) and MA (56.27?±?1.08%) after 6 h of dissolution. DSC endothermic peak for MA in SD 6 was broadened and shifted to lower temperature (194 °C). FTIR spectroscopy confirmed no chemical changes in MA SD, but establishment of hydrogen bonding between hydroxyl groups of PEA with amine groups of MA was observed by the red shift of OH band in SD samples. The SD was stable (P?>?0.05) at ambient condition for up to 90 days, reflecting by the drug content, dissolution profiles and solubility of the formulation.

Conclusions

POPEA demonstrated surface lowering and wettability effects in improving the aqueous solubility and dissolution rate of MA in SD. The crystalline drug was transformed to amorphous formulation, via solubilisation and crystallisation inhibition effect of the PEA.

     

The Development of Thermal Nanoprobe Methods as a Means of Characterizing and Mapping Plasticizer Incorporation into Ethylcellulose Films

Purpose

The phase composition and distribution of ethylcellulose (EC) films containing varying amounts of the plasticizer fractionated coconut oil (FCO) were studied using a novel combination of thermal and mapping approaches.

Methods

The thermal and thermomechanical properties of films containing up to 30% FCO were characterized using modulated temperature differential scanning calorimetry (MTDSC) and dynamic mechanical analysis (DMA). Film surfaces were mapped using atomic force microscopy (AFM; topographic and pulsed force modes) and the composition of specific regions identified using nanothermal probes.

Results

Clear evidence of distinct conjugate phases was obtained for the 20?C30% FCO/EC film systems. We suggest a model whereby the composition of the distinct phases may be estimated via consideration of the glass transition temperatures observed using DSC and DMA. By combining pulsed force AFM and nano-thermal analysis we demonstrate that it is possible to map the two separated phases. In particular, the use of thermal probes allowed identification of the distinct regions via localized thermomechanical analysis, whereby nanoscale probe penetration is measured as a function of temperature.

Conclusion

The study has indicated that by using thermal and imaging techniques in conjunction it is possible to both identify and map distinct regions in binary films.     

Critical Solvent Properties Affecting the Particle Formation Process and Characteristics of Celecoxib-Loaded PLGA Microparticles via Spray-Drying

Purpose

It is imperative to understand the particle formation mechanisms when designing advanced nano/microparticulate drug delivery systems. We investigated how the solvent power and volatility influence the texture and surface chemistry of celecoxib-loaded poly (lactic-co-glycolic acid) (PLGA) microparticles prepared by spray-drying.

Methods

Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA).

Results

Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures.

Conclusions

The particle formation process is mainly governed by the PLGA precipitation rate, which is solvent-dependent, and the migration rate of celecoxib molecules during drying. The texture and surface chemistry of the spray-dried PLGA microparticles can therefore be tailored by adjusting the solvent composition.

Effect of Milling on Particle Shape and Surface Energy Heterogeneity of Needle-Shaped Crystals

Purpose

Milling and micronization of particles are routinely employed in the pharmaceutical industry to obtain small particles with desired particle size characteristics. The aim of this study is to demonstrate that particle shape is an important factor affecting the fracture mechanism in milling.

Methods

Needle-shaped crystals of the β polymorph of D-mannitol were prepared from recrystallization in water. A portion of the recrystallized materials was ball-milled. Unmilled and milled sieved fractions of recrystallized D-mannitol were analyzed by dynamic image analysis (DIA) and inverse gas chromatography (IGC) at finite concentration to explain the breakage/fracture behavior.

Results

In the process of ball-milling, D-mannitol preferentially fractured along their shortest axis, exposing (011) plane with increased hydrophilicity and increased bounding rectangular aspect ratio. This is in contrary to attachment energy modeling which predicts a fracture mechanism across the (010) plane with increased hydrophobicity, and small change in particle shape.

Conclusions

Crystal size, and more importantly, crystal shape and facet-specific mechanical properties, can dictate the fracture/cleavage behavior of organic crystalline materials. Thorough understanding of the crystal slip systems, combining attachment energy prediction with particle shape and surface characterization using DIA and IGC, are important in understanding fracture behavior of organic crystalline solids in milling and micronization.     

Protein-Silicone Oil Interactions: Comparative Effect of Nonionic Surfactants on the Interfacial Behavior of a Fusion Protein

Purpose

To study the effect of three nonionic surfactants on the protein-silicone oil interactions.

Methods

The adsorption of Tween® 80, Pluronic® F68 and Tween® 20 at the silicone oil/water interface (using shifts in frequency (ΔF) and resistance (ΔR) with quartz crystal microbalance) was compared to the adsorption at air/water interface (using surface tension). Effect of surfactants on protein adsorption to the silicone oil/water interface was studied in sequential- and co-adsorption modes. Protein-surfactant binding in the bulk was measured using dynamic surface tension method.

Results

Saturation of air/water and silicone oil/water interfaces by surfactants was observed at similar bulk concentrations. ΔF due to protein adsorption to the interface decreased only when surfactant was present as a pre-adsorbed species. Insignificant differences in the dynamic surface tension values of surfactant solutions were observed in the presence of protein.

Conclusions

Similar hydrophobic forces were responsible for driving the surfactant adsorption at both air/water and silicone oil/water interfaces. Surfactants were effective in reducing the protein adsorption to the silicone oil only when introduced before or along with the protein. No significant binding between the protein and surfactants was observed in the bulk.     

Image Analysis Quantification of Sticking and Picking Events of Pharmaceutical Powders Compressed on a Rotary Tablet Press Simulator

Purpose

The aim of this work was to develop a quantification method based on image analysis, able to characterize sticking during pharmaceutical tableting. Relationship between image analysis features and relevant mechanical parameters recorded on an instrumented tablet press simulator were investigated.

Methods

Image analysis, based on gray levels co-occurrence matrices (GLCM), generated textural features of the tablet surface. The tableting simulator (Stylcam® 200R, Medelpharm), instrumented with force and displacement transducers, provided accurate records. The tablet defects and compaction process parameters were studied using three pharmaceutical powders (Fast-Flo® lactose, anhydrous Emcompress® and Avicel® PH200 microcrystalline cellulose), five compression pressures (60 to 250 MPa), five lubricating levels, and three types of punches (standard steel, amorphous hard carbon and anti-sticking punches).

Results

Texture parameters made it possible to quantify with precision tablets’ aspect. The selected parameter IC2 (Information on Correlation 2) plotted versus the ratio between the ejection shear stress (Esh) and the compression pressure (Cp) let appear a relevant knowledge space where it was possible to identify a normal and a degraded tableting mode. A positive link between those two parameters was shown.

Conclusion

Since the Esh/Cp ratio was related to image analysis results, it proved to be an interesting defect tag.     

Gelatin Nano-coating for Inhibiting Surface Crystallization of Amorphous Drugs

Purpose

Inhibit the fast surface crystallization of amorphous drugs with gelatin nano-coatings.

Methods

The free surface of amorphous films of indomethacin or nifedipine was coated by a gelatin solution (type A or B) and dried. The coating’s effect on surface crystallization was evaluated. Coating thickness was estimated from mass change after coating.

Results

For indomethacin (weak acid, pK_a?=?4.5), a gelatin coating of either type deposited at pH 5 and 10 inhibited its fast surface crystal growth. The coating thickness was 20?±?10 nm. A gelatin coating deposited at pH 3, however, provided no protective effect. These results suggest that an effective gelatin coating does not require that the drug and the polymer have opposite charges. The ineffective pH 3 coating might reflect the poor wetting of indomethacin’s neutral, hydrophobic surface by the coating solution. For nifedipine (weak base, pK_a?=?2.6), a gelatin coating of either type deposited at pH 5 inhibited its fast surface crystal growth.

Conclusions

Gelatin nano-coatings can be conveniently applied to amorphous drugs from solution to inhibit fast surface crystallization. Unlike strong polyelectrolyte coatings, a protective gelatin coating does not require strict pairing of opposite charges. This could make gelatin coating a versatile, pharmaceutically acceptable coating for stabilizing amorphous drugs.

     

CD44 Targeting Magnetic Glyconanoparticles for Atherosclerotic Plaque Imaging

Purpose

The cell surface adhesion molecule CD44 plays important roles in the initiation and development of atherosclerotic plaques. We aim to develop nanoparticles that can selectively target CD44 for the non-invasive detection of atherosclerotic plaques by magnetic resonance imaging.

Methods

Magnetic glyconanoparticles with hyaluronan immobilized on the surface have been prepared. The binding of these nanoparticles with CD44 was evaluated in vitro by enzyme linked immunosorbent assay, flow cytometry and confocal microscopy. In vivo magnetic resonance imaging of plaques was performed on an atherosclerotic rabbit model.

Results

The magnetic glyconanoparticles can selectively bind CD44. In T2* weighted magnetic resonance images acquired in vivo, significant contrast changes in aorta walls were observed with a very low dose of the magnetic nanoparticles, allowing the detection of atherosclerotic plaques. Furthermore, imaging could be performed without significant delay after probe administration. The selectivity of hyaluronan nanoparticles in plaque imaging was established by several control experiments.

Conclusions

Magnetic nanoparticles bearing surface hyaluronan enabled the imaging of atherosclerotic plaques in vivo by magnetic resonance imaging. The low dose of nanoparticles required, the possibility to image without much delay and the high biocompatibility are the advantages of these nanoparticles as contrast agents for plaque imaging.