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Temozolomide (TMZ) is the standard of care chemotherapy drug for treating glioblastomas (GBMs), the most aggressive cancer that affects people of all ages. However, its therapeutic efficacy is limited by the drug resistance mediated by a DNA repair protein, O(6)-methylguanine-DNA methyltransferase (MGMT), which eliminates the TMZ-induced DNA lesions. Here we report the development of an iron oxide nanoparticle (NP) system for targeted delivery of siRNAs to suppress the TMZ-resistance gene (MGMT). We show that our NP is able to overcome biological barriers, bind specifically to tumor cells, and reduce MGMT expression in tumors of mice bearing orthotopic GBM serially-passaged patient-derived xenografts. The treatment with sequential administration of this NP and TMZ resulted in increased apoptosis of GBM stem-like cells, reduced tumor growth, and significantly-prolonged survival as compared to mice treated with TMZ alone. This study introduces an approach that holds great promise to improve the outcomes of GBM patients.

Layer-by-layer self-assembly can be used to incorporate amphiphilic molecules into multilayered polyelectrolyte architectures. This review examines equilibrium LbL assemblies constructed by direct adsorption from aqueous solution. LbL systems have not only provided fundamental insight into the nature of polyion–surfactant complexation, but have also yielded functional materials with useful surface, optical, and electronic properties.

Cannonball jellyfish, often commercialized as salted, dried jellyfish (SDJ), is an emerging fishery in the USA and a great source of collagen, which can be utilized for developing novel marine gelatin powders. The aim of this study was to determine the feasibility of producing gelatin powders with gelling properties from SDJ using a mild acid hydrolysis and freeze-drying procedure as well as to evaluate their physico-chemical properties. The findings revealed that the resultant gelatin powders had a moisture (g/100 g, dry basis, d.b.), crude protein (g/100 g, d.b.), ash content (g/100 g, d.b.) and water activity values of 4.82, 29.54, 56.61, and 0.09, respectively. Sodium, Al, and S were the main minerals detected in the jellyfish gelatin powders, which were agglomerated and had irregular morphologies with a mean particle size of 12.8 μm. Gels prepared with 5, 6.67, and 10% (w/v) jellyfish gelatin powder had Bloom values lower than 4.2 g; melting temperatures between 15.09 and 16.12 °C and their rheological behavior was effectively characterized by the Herschel-Bulkley flow model, which revealed non-Newtonian behavior and shear thinning phenomena. Higher apparent viscosities, yield stress, and consistency index values were observed in the gels prepared at higher concentrations of jellyfish gelatin powders and at lower evaluated temperatures. This study illustrates (for the first time) the feasibility of producing novel marine gelatin powders from SDJ, which have the potential to be used as gelling, thickening and/or binding agents in several food applications.

Despite the preponderance of iron oxide nanoparticles (NPs) designed for theranostic applications, widespread clinical translation of these NPs lags behind. A better understanding of how NP pharmacokinetics vary between small and large animal models is needed to rapidly customize NPs for optimal performance in humans. Here we use noninvasive magnetic resonance imaging (MRI) to track iron oxide NPs through a large number of organ systems in vivo to investigate NP biokinetics in both mice and nonhuman primates. We demonstrate that pharmacokinetics are similar between mice and macaques in the blood, liver, spleen, and muscle, but differ in the kidneys, brain, and bone marrow. Our study also demonstrates that full-body MRI is practical, rapid and cost-effective for tracking NPs non-invasively with high spatiotemporal resolution. Our techniques using a nonhuman primate model may provide a platform for testing a range of NP formulations.

Traumatic brain injury (TBI) is the leading cause of disability and death in children and adults under 45, with approximately ten million new cases per year worldwide. Significant progress has been made in understanding the complex pathophysiological response to TBI; however, reducing the damage associated with the reactive oxygen species (ROS)-dependent secondary phase of the injury remains a substantial challenge. The development of an image-guided, Gd-conjugated, oxygen reactive polymer (ORP) to reduce ROS levels in damaged brain tissue is reported. ORP effectively sequesters ROS while remaining biocompatible even at elevated concentrations. ORP is retained in damaged brains of controlled cortical impact (CCI) mouse models of TBI for over 24 h when injected intravenously immediately and up to 3 h post-CCI. The polymer reduces neurodegeneration tenfold and gliosis twofold in these mouse models. ORP shows initial promise as an effective therapy for TBI and helps provide a better understanding of nanomaterial interaction with damaged brain.

Convection-enhanced delivery (CED) provides direct access of infusates to brain tumors; however, clinical translation of this technology has not been realized because of the inability to accurately visualize infusates in real-time and lack of targeting modalities against diffuse cancer cells. In this study, we use time-resolved MRI to reveal the kinetics of CED processes in a glioblastoma (GBM) model using iron oxide nanoparticles (NP) modified with a glioma-targeting ligand, chlorotoxin (CTX). Mice bearing orthotopic human GBM tumors were administered a single dose of targeted CTX-conjugated NP (NPCP-CTX) or nontargeted NP (NPCP) via CED. High-resolution T2-weighted, T2*-weighted, and quantitative T2 MRI were utilized to image NP delivery in real time and determined the volume of distribution (VD) of NPs at multiple time points over the first 48 hours post-CED. GBM-specific targeting was evaluated by flow cytometry and intracellular NP localization by histologic assessment. NPCP-CTX produced a VD of 121 ± 39 mm3 at 24 hours, a significant increase compared with NPCP, while exhibiting GBM specificity and localization to cell nuclei. Notably, CED of NPCP-CTX resulted in a sustained expansion of VD well after infusion, suggesting a possible active transport mechanism, which was further supported by the presence of NPs in endothelial and red blood cells. In summary, we show that time-resolved MRI is a suitable modality to study CED kinetics, and CTX-mediated CED facilitates extensive distribution of infusate and specific targeting of tumor cells. Significance: MRI is used to monitor convection-enhanced delivery in real time using a nanoparticle-based contrast agent, and glioma-specific targeting significantly improves the volume of distribution in tumors.

Hepatocellular carcinoma (HCC) is an increasingly lethal malignancy for which management is critically dependent on accurate imaging. Glypican-3 (GPC3) is a cell surface receptor overexpressed in most HCCs and provides a unique target for molecular diagnostics. The use of monoclonal antibodies (mAbs) that target GPC3 (αGPC3) in PET imaging has shown promise but comes with inherent limitations associated with mAbs such as long circulation times. This study used 89Zr-conjugated F(ab′)2 fragments directed against GPC3 (89Zr-αGPC3-F(ab′)2) to evaluate the feasibility of the fragments as a diagnostic immuno-PET imaging probe. Methods: Immobilized ficin was used to digest αGPC3, creating αGPC3-F(ab′)2 fragments subsequently conjugated to 89Zr. In vivo biodistribution and PET studies were performed on GPC3-expressing HepG2 and GPC3-nonexpressing RH7777 orthotopic xenografts. Results: Reliable αGPC3-F(ab′)2 production via immobilized ficin digestion was verified by high-performance liquid chromatography and sodium dodecyl sulfate polyacrylamide gel electrophoresis. 89Zr-αGPC3-F(ab′)2 demonstrated F(ab′)2-dependent, antigen-specific cell binding. HepG2 tumor uptake was higher than any other tissue, peaking at 100 ± 21 percentage injected dose per gram (%ID/g) 24 h after injection, a value 33- to 38-fold higher than GPC3-nonexpressing RH7777 tumors. The blood half-life of the 89Zr-αGPC3-F(ab′)2 conjugate was approximately 11 h, compared with approximately 115 h for historic mAb controls. This shorter half-life enabled clear tumor visualization on PET 4 h after administration, with a resultant peak tumor-to-liver contrast ratio of 23.3. Blocking antigen-expressing tumors with an excess of nonradiolabeled αGPC3 resulted in decreased tumor uptake similar to native liver. The kidneys exhibited high tissue uptake, peaking at 24 h with 83 ± 12 %ID/g. HepG2 tumors ranging from 1.5 to 7 mm were clearly visible on PET, whereas larger RH7777 tumors displayed signal lower than background liver tissue. Conclusion: This study demonstrates the feasibility of using 89Zr-αGPC3-F(ab′)2 for intrahepatic tumor localization with small-animal PET. Faster blood clearance and lower background liver uptake enable excellent signal-to-noise ratios at early time points. Increased renal uptake is similar to that as has been seen with clinical radioactive peptide imaging. 89Zr-αGPC3-F(ab′)2 addresses some of the shortcomings of whole-antibody immuno-PET probes. Further optimization is warranted to maximize probe sensitivity and specificity in the process of clinical translation.

Resistance to temozolomide (TMZ) based chemotherapy in glioblastoma multiforme (GBM) has been attributed to the upregulation of the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT). Inhibition of MGMT using O(6)-benzylguanine (BG) has shown promise in these patients, but its clinical use is hindered by poor pharmacokinetics that leads to unacceptable toxicity. To improve BG biodistribution and efficacy, we developed superparamagnetic iron oxide nanoparticles (NP) for targeted convection-enhanced delivery (CED) of BG to GBM. The nanoparticles (NPCP-BG-CTX) consist of a magnetic core coated with a redox-responsive, cross-linked, biocompatible chitosan-PEG copolymer surface coating (NPCP). NPCP was modified through covalent attachment of BG and tumor targeting peptide chlorotoxin (CTX). Controlled, localized BG release was achieved under reductive intracellular conditions and NPCP-BG-CTX demonstrated proper trafficking of BG in human GBM cells in vitro. NPCP-BG-CTX treated cells showed a significant reduction in MGMT activity and the potentiation of TMZ toxicity. In vivo, CED of NPCP-BG-CTX produced an excellent volume of distribution (Vd) within the brain of mice bearing orthotopic human primary GBM xenografts. Significantly, concurrent treatment with NPCP-BG-CTX and TMZ showed a 3-fold increase in median overall survival in comparison to NPCP-CTX/TMZ treated and untreated animals. Furthermore, NPCP-BG-CTX mitigated the myelosuppression observed with free BG in wild-type mice when administered concurrently with TMZ. The combination of favorable physicochemical properties, tumor cell specific BG delivery, controlled BG release, and improved in vivo efficacy demonstrates the great potential of these NPs as a treatment option that could lead to improved clinical outcomes.

Investigations into the blood oxygenation level-dependent (BOLD) functional MRI signal have used respiratory challenges with the aim of probing cerebrovascular physiology. Such challenges have altered the inspired partial pressures of either carbon dioxide or oxygen, typically to a fixed and constant level (fixed inspired challenge (FIC)). The resulting end-tidal gas partial pressures then depend on the subject's metabolism and ventilatory responses. In contrast, dynamic end-tidal forcing (DEF) rapidly and independently sets end-tidal oxygen and carbon dioxide to desired levels by altering the inspired gas partial pressures on a breath-by-breath basis using computer-controlled feedback. This study implements DEF in the MRI environment to map BOLD signal reactivity to CO2. We performed BOLD (T2*) contrast FMRI in four healthy male volunteers, while using DEF to provide a cyclic normocapnichypercapnic challenge, with each cycle lasting 4 mins (PetCO2 mean±s.d., from 40.9 ± 1.8 to 46.4 ± 1.6 mm Hg). This was compared with a traditional fixed-inspired (FiCO2 = 5%) hypercapnic challenge (PetCO2 mean±s.d., from 38.2 ± 2.1 to 45.6 ± 1.4 mm Hg). Dynamic end-tidal forcing achieved the desired target PetCO2 for each subject while maintaining PetCO2 constant. As a result of CO2-induced increases in ventilation, the FIC showed a greater cyclic fluctuation in PetCO2. These were associated with spatially widespread fluctuations in BOLD signal that were eliminated largely by the control of PetCO2 during DEF. The DEF system can provide flexible, convenient, and physiologically well-controlled respiratory challenges in the MRI environment for mapping dynamic responses of the cerebrovasculature.

Combined blood oxygenation level-dependent (BOLD) and arterial spin labeling (ASL) functional MRI (fMRI) was performed for simultaneous investigation of neurovascular coupling in the primary visual cortex (PVC), primary motor cortex (PMC), and supplementary motor area (SMA). The hypercapnia-calibrated method was employed to estimate the fractional change in cerebral metabolic rate of oxygen consumption (CMR(O2)) using both a group-average and a per-subject calibration. The group-averaged calibration showed significantly different CMR(O2)-CBF coupling ratios in the three regions (PVC: 0.34 +/- 0.03; PMC: 0.24 +/- 0.03; and SMA: 0.40 +/- 0.02). Part of this difference emerges from the calculated values of the hypercapnic calibration constant M in each region (M(PVC) = 6.6 +/- 3.4, M(PMC) = 4.3 +/- 3.5, and M(SMA) = 7.2 +/- 4.1), while a relatively minor part comes from the spread and shape of the sensorimotor BOLD-CBF responses. The averages of the per-subject calibrated CMR(O2)-CBF slopes were 0.40 +/- 0.04 (PVC), 0.31 +/- 0.03 (PMC), and 0.44 +/- 0.03 (SMA). These results are 10-30% higher than group-calibrated values, and are potentially more useful for quantifying individual differences in focal functional responses. The group-average calibrated motor coupling value is increased to 0.28 +/- 0.03 when stimulus-correlated increases in end-tidal CO(2) are included. Our results support the existence of regional differences in neurovascular coupling, and argue for the importance of achieving optimal accuracy in hypercapnia calibrations to resolve method-dependent variations in published results.

Alternating multilayers of amphiphile, 4-{4-[Methyl-(4-octadecylcarbamoyl-butyl)-amino]-phenylazo}-benzenesulfonic acid (S-azo-C 18 ), and stearic acid were deposited on hydrophobized silica surfaces using the Langmuir–Blodgett technique. Ellipsometry, UV–visible spectroscopy, and second harmonic generation were used to characterize the films, demonstrating reproducible deposition and suggesting a well ordered film structure. Despite the appearance of order at the macroscopic level, neutron and X-ray scattering results unequivocally show that there is considerable disorder, with significant interpenetration between the stearic acid and S-azo-C 18 layers. These results suggest that molecular disorder in Langmuir–Blodgett deposited multilayer films may often go unrecognized mainly because the macroscopic probes based on these optical measurements are not adequate for determining the molecular level structural order.

We describe the integration of a photochromic azobenzene dye into electrostatically bound polyelectrolyte multilayers. Two different deposition techniques are compared: electrostatic self-assembly (ESA) and polyelectrolyte spin-assembly. The polyelectrolytes used were PEI (polyethylenimine) and PAZO (poly[1-[4-(3-carboxy-4-hydroxyphenylazo) benzenesulfonamido]-1,2-ethanediyl, sodium salt]). Successful incorporation of the azobenzene dye Direct red 80 (DR80) into ESA and spin-assembled multilayered films (PEI/DR80) is demonstrated. We find that coadsorption of DR80 and PAZO on a PEI surface occur in different proportions and packing densities, depending on the assembly technique selected. We find that using DR80 as a coadsorbing agent can dramatically enhance the rate of PAZO adsorption, and we observe different deposition rates for DR80 and PAZO when the two materials adsorb simultaneously from a common solution.

Water-soluble, cationic, anionic, and neutral polymers are used to form various repeat trilayer films via ionic self-assembly (ISA) and spin-assembly. These multilayer thin films assemble through physical entanglement, electrostatic, and/or H-bonding interactions. Spin assembly has the advantage over ISA in constructing stable multilayers when polyelectrolytes with like charge are assembled in adjacent layers. These multilayers do not desorb in water over a long period of time. In contrast to spin assembly, the ISA method deposits only a minimal amount of polyelectrolyte on top of a like-charged layer. The mechanical entanglement that is responsible for the deposition of like-charged species in spin assembly is probably lacking in ISA. The ability to construct repeated trilayers or multilayers composed of polycations, polyanions, and neutral polymers allows the fabrication of multilayer thin films with the desired interfacial structure and interactions. In this work, polyelectrolytes with NLO chromophores...

In this paper, we report the fabrication and characterization of polyaniline colloid (PANIC) multilayer thin films prepared from PANIC aqueous dispersion and a polyelectrolyte solution. Both chiral...

Polyelectrolyte thin films composed of alternating layers were spin-assembled by sequentially dropping cationic and anionic aqueous solutions onto a spinning substrate. In this work, we show the applicability of our technique to multiple systems and present two methods for producing linear film growth. The polycations used were PEI (poly(ethylenimine), PDDA (poly(diallyldimethylammonium chloride), PAH (poly(allylamine hydrochloride), and two poly(propylenimine) dendrimers (generations 3.0 and 4.0). The polyanions used were PAZO (poly[1-[4-(3-carboxy-4-hydroxy-phenylazo)benzene sulfonamido]-1,2-ethanediyl, sodium salt]), PSS (poly(styrenesulfonate)), and PAA (poly(acrylic acid)). Layer thicknesses for all systems were determined using single-wavelength ellipsometry. UV-vis spectroscopy was used to measure deposition amounts in films containing the chromophoric polyanions PAZO and PSS. We demonstrate the ability to spin-assemble multilayered thin films up to 50 bilayers with linear increases in deposition amount between bilayers. Additionally, we show that layers of a single polyelectrolyte species can be spin-assembled with multiple deposition cycles in which consistent amounts are deposited in each cycle. In a comparison of films built from two dendrimer generations, films incorporating generation 3.0 dendrimer and PAZO show signs of higher interpenetration between layers and a more collapsed film structure than films assembled from generation 4.0 dendrimer and PAZO. Our results also suggest that a substrate effect influences the packing density of the first few bilayers, eventually dissipating around a film thickness of 50-80 A.

Repeated bilayers of a polycation and a polyanion were assembled by adsorption from their aqueous solutions. The polycations used were PEI (poly(ethylenimine)), PAH (poly(allylamine hydrochloride)), and generation 3.0 dendrimer (poly(propylenimine)). The polyanion was PAZO (poly[1-[4-(3-carboxy-4-hydroxyphenylazo)benzenesulfonamido]-1,2-ethanediyl, sodium salt]). Second harmonic generation (SHG) and UV−vis spectroscopy were used to study the structure and formation of the superlattices. The linear increase in absorbance versus the number of bilayers suggested that a uniform and consistent amount of polymer adsorbed during each deposition cycle. The observation of a second harmonic (SH) signal from the film showed that the conjugated chromophores in the PAZO polymer were aligned with a net dipole. However, the SHG signal did not continue to increase as the number of bilayers was increased. On the basis of thorough studies of the UV and SH properties for each bilayer for 10 total bilayers, we propose that t...

Graded levels of supplemental inspired oxygen were investigated for their viability as a noninvasive method of obtaining intravascular magnetic resonance image contrast. Administered hyperoxia has been shown to be effective as a blood oxygenation level-dependent contrast agent for magnetic resonance imaging (MRI); however, it is known that high levels of inspired fraction of oxygen result in regionally decreased perfusion in the brain potentially confounding the possibility of using hyperoxia as a means of measuring blood flow and volume. Although the effects of hypoxia on blood flow have been extensively studied, the hyperoxic regime between normoxia and 100% inspired oxygen has been only intermittently studied. Subjects were studied at four levels of hyperoxia induced during a single session while perfusion was measured using arterial spin labelling MRI. Reductions in regional perfusion of grey matter were found to occur even at moderate levels of hyperoxia; however, perfusion changes at all oxygen levels were relatively mild (less than 10%) supporting the viability of hyperoxia-induced contrast.