Xiuling Lu

Quercetin-Containing Self-Nanoemulsifying Drug Delivery System for Improving Oral Bioavailability

Quercetin is a dietary flavonoid with potential chemoprotective effects, but has low bioavailability because of poor aqueous solubility and low intestinal absorption. A quercetin-containing self-nanoemulsifying drug delivery system (Q-SNEDDS) was developed to form oil-in-water nanoemulsions in situ for improving quercetin oral bioavailability. On the basis of the quercetin solubility, emulsifying ability, and stability after dispersion in an aqueous phase, an optimal SNEDDS consisting of castor oil, Tween® 80, Cremophor® RH 40, and PEG 400 (20:16:34:30, w/w) was identified. Upon mixing with water, Q-SNEDDS formed a nanoemulsion having a droplet size of 208.8 ± 4.5 nm and zeta potential of -26.3 ± 1.2 mV. The presence of Tween® 80 and PEG 400 increased quercetin solubility and maintained supersaturated quercetin concentrations (5 mg/mL) for >1 month. The optimized Q-SNEDDS significantly improved quercetin transport across a human colon carcinoma (Caco-2) cell monolayer. Fluorescence imaging demonstrated rapid absorption of the Q-SNEDDS within 40 min of oral ingestion. Following oral administration of Q-SNEDDS in rats (15 mg/kg), the area under the concentration curve and maximum concentration of plasma quercetin after 24 h increased by approximately twofold and threefold compared with the quercetin control suspension. These data suggest that this Q-SNEDDS formulation can enhance the solubility and oral bioavailability of quercetin for appropriate clinical application.

Neutron-Activatable Holmium-Containing Mesoporous Silica Nanoparticles as a Potential Radionuclide Therapeutic Agent for Ovarian Cancer

Mesoporous silica nanoparticles (MSNs) were explored as a carrier material for the stable isotope 165Ho and, after neutron capture, its subsequent therapeutic radionuclide, 166Ho (half-life, 26.8 h), for use in radionuclide therapy of ovarian cancer metastasis. Methods: 165Ho-MSNs were prepared using 165Ho-acetylacetonate and MCM-41 silica particles, and stability was determined after irradiation in a nuclear reactor (reactor power, 1 MW; thermal neutron flux of approximately 5.5 × 1012 neutrons/cm2·s). SPECT/CT and tissue biodistribution studies were performed after intraperitoneal administration of 166Ho-MSNs to SKOV-3 ovarian tumor–bearing mice. Radiotherapeutic efficacy was studied by using PET/CT with 18F-FDG to determine tumor volume and by monitoring survival. Results: The holmium-MSNs were able to withstand long irradiation times in a nuclear reactor and did not release 166Ho after significant dilution. SPECT/CT images and tissue distribution results revealed that 166Ho-MSNs accumulated predominantly in tumors (32.8% ± 8.1% injected dose/g after 24 h; 81% ± 7.5% injected dose/g after 1 wk) after intraperitoneal administration. PET/CT images showed reduced 18F-FDG uptake in tumors, which correlated with a marked increase in survival after treatment with approximately 4 MBq of 166Ho-MSNs. Conclusion: The retention of holmium in nanoparticles during irradiation and in vivo after intraperitoneal administration as well as their efficacy in extending survival in tumor-bearing mice underscores their potential as a radiotherapeutic agent for ovarian cancer metastasis.

Long circulating self-assembled nanoparticles from cholesterol-containing brush-like block copolymers for improved drug delivery to tumors.

Amphiphilic brush-like block copolymers composed of polynorbonene-cholesterol/poly(ethylene glycol) (P(NBCh9-b-NBPEG)) self-assembled to form a long circulating nanostructure capable of encapsulating the anticancer drug doxorubicin (DOX) with high drug loading (22.1% w/w). The release of DOX from the DOX-loaded P(NBCh9-b-NBPEG) nanoparticles (DOX-NPs) was steady at less than 2% per day in PBS. DOX-NPs were effectively internalized by human cervical cancer cells (HeLa) and showed dose-dependent cytotoxicity, whereas blank nanoparticles were noncytotoxic. The DOX-NPs demonstrated a superior in vivo circulation time relative to that of free DOX. Tissue distribution and in vivo imaging studies showed that DOX-NPs preferentially accumulated in tumor tissue with markedly reduced accumulation in the heart and other vital organs. The DOX-NPs greatly improved survival and significantly inhibited tumor growth in tumor-bearing SCID mice compared to that for the untreated and free DOX-treated groups. The results indicated that self-assembled P(NBCh9-b-NBPEG) may be a useful carrier for improving tumor delivery of hydrophobic anticancer drugs.

A Biocompatible and Biodegradable Protein Hydrogel with Green and Red Autofluorescence: Preparation, Characterization and In Vivo Biodegradation Tracking and Modeling

Because of its good biocompatibility and biodegradability, albumins such as bovine serum albumin (BSA) and human serum albumin (HSA) have found a wide range of biomedical applications. Herein, we report that glutaraldehyde cross-linked BSA (or HSA) forms a novel fluorescent biological hydrogel, exhibiting new green and red autofluorescence in vitro and in vivo without the use of any additional fluorescent labels. UV-vis spectra studies, in conjunction with the fluorescence spectra studies including emission, excitation and synchronous scans, indicated that three classes of fluorescent compounds are presumably formed during the gelation process. SEM, FTIR and mechanical tests were further employed to investigate the morphology, the specific chemical structures and the mechanical strength of the as-prepared autofluorescent hydrogel, respectively. Its biocompatibility and biodegradability were also demonstrated through extensive in vitro and in vivo studies. More interestingly, the strong red autofluorescence of the as-prepared hydrogel allows for conveniently and non-invasively tracking and modeling its in vivo degradation based on the time-dependent fluorescent images of mice. A mathematical model was proposed and was in good agreement with the experimental results. The developed facile strategy to prepare novel biocompatible and biodegradable autofluorescent protein hydrogels could significantly expand the scope of protein hydrogels in biomedical applications.

A solid-phase adsorption method for PEGylation of human serum albumin and staphylokinase: preparation, purification and biochemical characterization

A solid-phase adsorption method was developed to circumvent the disadvantage of the conventional liquid-phase PEGylation, i.e. the heterogeneity of the PEGylated products. The model proteins, human serum albumin (HSA) and staphylokinase (SAK), were adsorbed on the ion exchange chromatography media, followed by PEGylation with succinimidyl carbonate (SC)-mPEG5K and salt elution. Since PEGylation with SC-PEG5K alters the positive charge of the proteins, Q-Sepharose Big Beads and DEAE Sepharose Fast Flow were used for adsorption of HSA and SAK, respectively. Size exclusion chromatography and SDS-PAGE studies demonstrated that solid-phase PEGylation of proteins generate monoPEGylated proteins with the yield of 35–47%. Circular dichroism and intrinsic fluorescence studies showed that solid-phase PEGylation led to little conformational change of the proteins. Solid-phase PEGylation resulted in 35% loss in the biological activity of SAK, which is lower than the liquid-phase PEGylation (70%).

Self-assembled nanoparticles from thiol functionalized liquid crystalline brush block copolymers for dual encapsulation of doxorubicin and gold nanoparticles

We synthesized new amphiphilic brush liquid crystalline block copolymers (brush-chol-BCP) comprised of polymethacrylates bearing polyethylene oxide (PEO) in one block and polymethacrylates bearing a cholesterol mesogen with a hemitelechelic thiol end group. Polymethacrylate bearing PEO (PMA-g-PEO) was first synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT) and used as a macro-chain transfer agent to prepare block copolymer (PMA-g-PEO)-b-PC5MA-thioester (brush-chol-BCP-thioester). Brush-chol-BCP-thiol was obtained by the reduction of a thioester to thiol in the presence of butylamine. Gold nanoparticles (AuNPs) were prepared in situ with the brush-chol-BCP-thiol template via the reduction of gold ions and were stabilized by directly anchoring to the brush-chol-BCP-thiol chains through the coordination bonds with the thiol groups in the copolymer. The hydrophobic anticancer drug doxorubicin (DOX) was successfully encapsulated into AuNP-templated brush-chol-BCP-thiol via physical entrapment to form dual-encapsulated NPs with a high drug loading of 21.4% (w/w) and a high encapsulation efficiency of 85.6%. The dual-encapsulated NPs had an average size of 157 nm, spherical shape, excellent stability, and a sustained drug release pattern. More importantly, the dual-encapsulated NPs could be effectively internalized by human cervical cancer cells (Hela) and showed dose-dependent cytotoxicity, while the blank nanoparticles were non-cytotoxic at the tested concentrations. The results indicate that the brush-chol-BCP-thiol and their nanoparticles are promising carriers for dual encapsulation and delivery of an anticancer drug and metal nanoparticles.

Particle Margination and Its Implications on Intravenous Anticancer Drug Delivery

Abstract“Margination” refers to the movement of particles in flow toward the walls of a channel. The term was first coined in physiology for describing the behavior of white blood cells (WBCs) and platelets in blood flow. The margination of particles is desirable for anticancer drug delivery because it results in the close proximity of drug-carrying particles to the endothelium, where they can easily diffuse into cancerous tumors through the leaky vasculature. Understanding the fundamentals of margination may further lead to the rational design of particles and allow for more specific delivery of anticancer drugs into tumors, thereby increasing patient comfort during cancer treatment. This paper reviews existing theoretical and experimental studies that focus on understanding margination. Margination is a complex phenomenon that depends on the interplay between inertial, hydrodynamic, electrostatic, lift, van der Waals, and Brownian forces. Parameters that have been explored thus far include the particle size, shape, density, stiffness, shear rate, and the concentration and aggregation state of red blood cells (RBCs). Many studies suggested that there exists an optimal particle size for margination to occur, and that nonspherical particles tend to marginate better than spherical particles. There are, however, conflicting views on the effects of particle density, stiffness, shear rate, and RBCs. The limitations of using the adhesion of particles to the channel walls in order to quantify margination propensity are explained, and some outstanding questions for future research are highlighted.

Nanoparticles Containing Anti-inflammatory Agents as Chemotherapy Adjuvants II: Role of Plasma Esterases in Drug Release

The pre-administration of the anti-inflammatory drugs dexamethasone (DEX) and cortisone acetate reduces toxicity and enhances efficacy of anticancer agents in murine models and in human clinical trials (1–5). We previously reported on the formulation of the lipophilic dexamethasone palmitate ester (DEX-P) in nanoparticles (NPs) employing a microemulsion template engineering technique to achieve tumor-specific delivery of dexamethasone (6). The nanoparticles exhibited significantly enhanced stealth properties as indicated by reduced macrophage uptake and decreased adsorption of opsonin proteins in in vitro assays (6). Unexpectedly, preliminary biodistribution studies of NPs containing [3H]-DEX-P in tumor-bearing mice showed that the radiolabel was cleared from the circulation rapidly and exhibited high liver uptake. Our previous in vitro release studies demonstrated that rapid release of the radiolabel from the NPs was observed when 10% mouse plasma was used as the medium, while nominal release was observed in phosphate-buffered saline (PBS) buffer (6). Esterolysis of NP-associated DEX-P was presumed to be the main cause for the rapid drug release in plasma, as most of the released radioactivity was in the form of DEX and not DEX-P. High degradation rates of ester prodrugs in rodent plasma has been attributed to increased esterase activity, while only minimal degradation in human plasma has been observed (7–9). Based on our observation of the release of [3H]-DEX from NPs in mouse plasma, we studied the release of DEX from nanoparticles in various plasma sources as a guide for the design of future in vivo experiments.

Nanotemplate-engineered nanoparticles containing gadolinium for magnetic resonance imaging of tumors.

Purpose:To design nanoparticles containing accessible gadolinium atoms (Gd-NPs) as a contrast agent for magnetic resonance imaging of tumors. Methods:Nanoparticles containing phospholipid-chelates (phosphoethanolamine diethylenetriaminepentaacetate) and DSPE-PEG (MW5000) were prepared from Brij 78 and stearyl alcohol using the nanotemplate engineering approach. After addition of GdCl3, the presence of gadolinium on the surface of nanoparticles was quantified using inductively coupled plasma atomic emission spectroscopy. The in vitro relaxivities of the Gd-NPs in phosphate buffered saline were assessed at 4.7 T. The conditional binding constants of nanoparticle formulations were determined spectrophotometrically by competitive titration. Transmetallation kinetics of Gd3+ from nanoparticles with Cu2+ and Zn2+ as the competing ions was measured in acetate buffer. The biodistribution profiles, pharmacokinetics, and contrast enhancement in tumor region was studied after administration of Gd-NPs to nude mice bearing A549 lung carcinoma xenografts. Results:Gd-NPs with an average diameter of 138 nm possessing surface chelating functions were prepared from GRAS (generally regarded as safe) materials. The longitudinal relaxivity (r1) and transverse relaxivity (r2) of Gd-NPs in 10% fetal bovine serum at 4.7 T were 7.1 (±0.2) and 13.0 (±0.7) 1/mM/s, respectively. These pegylated Gd-NPs had enhanced relaxivities and exhibited particle size stability, sufficient binding affinity, and kinetic inertness under physiologic conditions. The contrast enhancement in tumors was demonstrated 40, 120, and 360 minutes after intravenous injection of Gd-NPs at a dose of 0.1 mmol Gd/kg. The Gd plasma concentration of Gd-NPs over a period of 24 hours fit a two-compartmental model with Clsys = 0.89 mL/h and MRT = 5.93 h. The amount of Gd that accumulated in the tumor region was consistent with the estimated value obtained by T1 measurements using MR imaging. Conclusion:Pegylated nanoparticles composed of biocompatible, biodegradable materials and possessing accessible Gd ions on their surface induce relaxivities in the bulk water signal and accumulated sufficiently in tumors, demonstrating their utility as potential magnetic resonance imaging tumor contrast enhancement agents.

Purification of Hemoglobin by Ion Exchange Chromatography in Flow-Through Mode with PEG as an Escort

Development of hemoglobin-based blood substitutes requires production of highly purified hemoglobin. Process of hemoglobin purification by ion exchange chromatography in flow-through mode was researched and optimized. Three kinds of media including, QMA Spherosil LS (Biosepra, France) and Q Sepharose Big Beads (Amersham Bioscience, Sweden), and an anion exchange membrane column, Mustang Q (PALL, USA) were investigated and compared. Adding polyethylene glycol (PEG) as an escort in ion exchange chromatography improved the purity and recovery, and the recovery in the chromatography was increased from 75 to 95%. The mechanism of PEG effects on chromatography was discussed. The optimal chromatography step, in combination with hypotonic dilution hemolyzing and membrane separation, formed an integrated hemoglobin purification process. The total recovery in the process was 87.6%. The activity of hemoglobin was well preserved: P50 23.2 mmHg, and Hill coefficient 2.31. The product appeared as a single band in SDS-PAGE, and GF-HPLC showed only one peak. The purity of the prepared hemoglobin was more than 99.9%. The optimized process is time saving and suitable for large-scale preparation of hemoglobin to provide materials for further preparation of blood substitutes.