Dominic V Mcgrath
Publications
Poly(ester-urethane-urea) (PEUU) is one of many synthetic biodegradable elastomers under scrutiny for biomedical and soft tissue applications. The goal of this study was to investigate the effect of the experimental parameters on mechanical properties of PEUUs following exposure to different degrading environments, similar to that of the human body, using linear regression, producing one predictive model. The model utilizes two independent variables of poly(caprolactone) (PCL) type and copolymer crystallinity to predict the dependent variable of maximum tangential modulus (MTM). Results indicate that comparisons between PCLs at different degradation states are statistically different (p 0.0003), while the difference between experimental and predicted average MTM is statistically negligible (p 0.02). The linear correlation between experimental and predicted MTM values is R(2) = 0.75.
Design, synthesis, characterization, and photodynamic activity of mitochondria specific asymmetric ZnPc–Rh B conjugates are described. Conjugation of asymmetric ZnPc–OH chromophores 3a and 3b with rhodamine B via the corresponding DIC-activated ester gave the desired near IR-absorbing asymmetric ZnPc–Rh B conjugates 1a and 1b. Conjugates 1a and 1b were shown to produce singlet oxygen upon illumination in DMSO, MeOH and THF. Fluorescence aggregation studies of the dyes 1a, 1b, 3a and 3b in DMSO and phosphate buffered saline (PBS) solution showed that conjugates 1a and 1b were less aggregated compared to the corresponding non-conjugates 3a and 3b suggesting that incorporation of Rh B lowered aggregation of the conjugates in the PBS solution. The four dyes studied have log D7.4 values between 2.31 and 2.48, with the sulfur-containing conjugate 1b being the most hydrophobic. All the dyes showed negligible dark toxicity when colon 26 cells were treated with 5 μM of the dyes while 10–15% cell death was observed for dye concentrations of 15 μM. Illumination (700 ± 40 nm, 45 J/cm2, 15 min) of the cells ([dye] = 15 μM) gave 70% cell death for ZnPc–Rh B conjugates 1a and 1b while no killing for non-conjugates 3a and 3b suggesting that the incorporation of the Rh B in the photosensitizer lowered the aggregation and subsequently improved cellular uptake and phototoxicity.
Abstract:
Monolayer films were fabricated from photochromic monodendrons with amphiphilic character. Amphiphilicity was established by a hydrophilic focal point (crown-ether) and hydrophilic tails (alkyl chains) that flank a photochromic azobenzene moiety. The monolayer forming properties of four generations of dendrons along with both stearic acid and a reference azobenzene compound with a carboxylic acid focal point group were determined.
Abstract:
Azobenzene-containing amphiphilic dendrimer was used to fabricate a photosensitive monolayer. A crown-ether moiety served as a polar head and a polyether fragment with long-chain alkyl tails providing hydrophobicity for an overall amphiphilic character. The architecture exhibited two dissimilar bulky terminal fragments.