Targeting in situ and imaging multiple inflammatory biomarkers with quantum dots in DSS model of colitis

Poster presented at Biomedical Technology Showcase 2006, Philadelphia, PA. Retrieved 18 Aug 2006 from http://www.biomed.drexel.edu/new04/Content/Biomed_Tech_Showcase/Poster_Presentations/Papazoglou_6.pdf.Inflammatory Bowel Disease affects nearly 1.5 million people. Currently, there are no efficient and reliable methods to quantify the degree of inflammation in these patients. The objective here was to image and quantify in an experimental model of colitis, MPO, IL1_ and TNF_ (proinflammatory cytokines) using Quantum Dots (QDs) conjugated with specific antibodies. The resulting fluorescence intensity was then used as a measure of concentration of MPO and in turn inflammation. The fluorescent images obtained from animals showed sequential increase in fluorescence intensity of MPO correlating (R = 0.96) with clinical disease. Fluorescent images also showed co-localization of all the three markers in both acute as well as chronic inflammation. These observations suggest that QD bioconjugates can be used nanotools to image biomarkers of inflammation

Paclitaxel-Loaded SCK Nanoparticles: An Investigation of Loading Capacity and Cell Killing Abilities <i>in Vitro</i>

Block copolymer nanoparticles having two different hydrodynamic diameters (120 nm vs 50 nm) and core diameters (60 nm vs 20 nm) with variable paclitaxel loading (5 to 20 wt % with respect to polymer weight, 4.4 μg/mL to 21.7 μg/mL paclitaxel concentrations in ultrapure water) were prepared for their <i>in vitro</i> cytotoxicity evaluation. Empty nanoparticles did not show any inherent cytotoxicity even at their highest concentration, whereas paclitaxel-loaded nanoparticles resulted in IC₅₀ values that were better than free paclitaxel at 2 h (0.021 μM vs 0.046 μM) incubation periods, and approximately equal to free paclitaxel at 72 h (0.004 μM vs 0.003 μM) continuous incubation. Confocal fluorescence microscopy images demonstrated that the drug-loaded nanoparticles internalized into KB cells within 2 h and released their payload, resulting in cytotoxicity as evident from the fragmented nuclei present. Functionalization of the nanoparticle surfaces with poly­(ethylene oxide) (2 kDa PEO, 5 PEO per block copolymer chain) did not affect the loading of paclitaxel or cell kill ability. No free paclitaxel was found in these nanoparticle formulations indicated by analytical assays

Type 1 Phototherapeutic Agents. 2. Cancer Cell Viability and ESR Studies of Tricyclic Diarylamines

Type 1 phototherapeutic agents based on diarylamines were assessed for free radical generation and evaluated in vitro for cell death efficacy in the U937 leukemia cancer cell line. All of the compounds were found to produce copious free radicals upon photoexcitation with UV-A and/or UV–B light, as determined by electron spin resonance (ESR) spectroscopy. Among the diarylamines, the most potent compounds were acridan (<b>4</b>) and 9-phenylacridan (<b>5</b>), with IC₅₀ values of 0.68 μM and 0.17 μM, respectively

Roles of Free Radicals in Type 1 Phototherapeutic Agents: Aromatic Amines, Sulfenamides, and Sulfenates

Detailed analyses of the electron spin resonance (ESR) spectra, cell viability, and DNA degradation studies are presented for the photolyzed Type I phototherapeutic agents: aromatic amines, sulfenamides, and sulfenates. The ESR studies provided evidence that copious free radicals can be generated from these N–H, N–S, and S–O containing compounds upon photoirradiation with UV/visible light. The analyses of spectral data allowed us to identify the free radical species. The cell viability studies showed that these agents after exposure to light exert cytotoxicity to kill cancer cells (U937 leukemia cell lines HTC11, KB, and HT29 cell lines) in a dosage- and time-dependent manner. We examined a possible pathway of cell death via DNA degradation by a plasmid cleavage assay for several compounds. The effects of photosensitization with benzophenone in the presence of oxygen were examined. The studies indicate that planar tricyclic amines and sulfenamides tend to form π-electron delocalized aminyl radicals, whereas nonplanar ones tend to yield nitroxide radicals resulting from the recombination of aminyl radicals with oxygen. The ESR studies coupled with the results of cell viability measurements and DNA degradation reveal that planar N-centered radicals can provide higher potency in cell death and allow us to provide some insights on the reaction mechanisms. We also found the formation of azatropylium cations possessing high aromaticity derived from azepines can facilitate secondary electron transfer to form toxic O₂^•– radicals, which can further exert oxidative stress and cause cell death

<i>In Vitro</i> Efficacy of Paclitaxel-Loaded Dual-Responsive Shell Cross-Linked Polymer Nanoparticles Having Orthogonally Degradable Disulfide Cross-Linked Corona and Polyester Core Domains

Paclitaxel-loaded shell cross-linked polymeric nanoparticles having an enzymatically and hydrolytically degradable poly­(lactic acid) core and a glutathione-responsive disulfide cross-linked poly­(oligoethylene glycol)-containing corona were constructed in aqueous solution and investigated for their stimuli-responsive release of the embedded therapeutics and <i>in vitro</i> cytotoxicity. Paclitaxel release from the nanoparticles in PBS buffer was accelerated in the presence of glutathione at both pH 5.5 and pH 7.4, reaching <i>ca</i>. 65% cumulative drug release after 8 d, whereas only <i>ca</i>. 50% and 35% extents of release were observed in the absence of glutathione at pH 5.5 and pH 7.4, respectively. Enzyme-catalyzed hydrolysis of the nanoparticle core resulted in the degradation of <i>ca</i>. 30% of the poly­(lactic acid) core to lactic acid within 12 h, with coincidently triggered paclitaxel release of <i>ca</i>. 37%, as opposed to only <i>ca</i>. 17% release from the uncatalyzed nanoparticles at pH 7.4. While empty nanoparticles did not show any inherent cytotoxicity at the highest tested concentrations, paclitaxel-loaded nanoparticles showed IC₅₀ values that were similar to those of free paclitaxel at 72 h incubation with KB cells and were more efficacious at <i>ca</i>. 3-fold lower IC₅₀ value (0.031 μM vs 0.085 μM) at 2 h of incubation. Against human ovarian adenocarcinoma cells, the paclitaxel-loaded nanoparticles exhibited a remarkable <i>ca</i>. 11-fold lower IC₅₀ than a Taxol-mimicking formulation (0.0007 μM vs 0.008 μM) at 72 h of incubation. These tunable dual-responsive degradable nanoparticles show great promise for delivery of paclitaxel to tumor tissues, given their superior <i>in vitro</i> efficacies compared to that of free paclitaxel and Taxol-mimicking formulations

<i>In Vitro</i> Efficacy of Paclitaxel-Loaded Dual-Responsive Shell Cross-Linked Polymer Nanoparticles Having Orthogonally Degradable Disulfide Cross-Linked Corona and Polyester Core Domains

Paclitaxel-loaded shell cross-linked polymeric nanoparticles having an enzymatically and hydrolytically degradable poly­(lactic acid) core and a glutathione-responsive disulfide cross-linked poly­(oligoethylene glycol)-containing corona were constructed in aqueous solution and investigated for their stimuli-responsive release of the embedded therapeutics and <i>in vitro</i> cytotoxicity. Paclitaxel release from the nanoparticles in PBS buffer was accelerated in the presence of glutathione at both pH 5.5 and pH 7.4, reaching <i>ca</i>. 65% cumulative drug release after 8 d, whereas only <i>ca</i>. 50% and 35% extents of release were observed in the absence of glutathione at pH 5.5 and pH 7.4, respectively. Enzyme-catalyzed hydrolysis of the nanoparticle core resulted in the degradation of <i>ca</i>. 30% of the poly­(lactic acid) core to lactic acid within 12 h, with coincidently triggered paclitaxel release of <i>ca</i>. 37%, as opposed to only <i>ca</i>. 17% release from the uncatalyzed nanoparticles at pH 7.4. While empty nanoparticles did not show any inherent cytotoxicity at the highest tested concentrations, paclitaxel-loaded nanoparticles showed IC₅₀ values that were similar to those of free paclitaxel at 72 h incubation with KB cells and were more efficacious at <i>ca</i>. 3-fold lower IC₅₀ value (0.031 μM vs 0.085 μM) at 2 h of incubation. Against human ovarian adenocarcinoma cells, the paclitaxel-loaded nanoparticles exhibited a remarkable <i>ca</i>. 11-fold lower IC₅₀ than a Taxol-mimicking formulation (0.0007 μM vs 0.008 μM) at 72 h of incubation. These tunable dual-responsive degradable nanoparticles show great promise for delivery of paclitaxel to tumor tissues, given their superior <i>in vitro</i> efficacies compared to that of free paclitaxel and Taxol-mimicking formulations