Detecting positive tumor margins and local malignant masses during surgery is critical for long-term patient survival. The use of image-guided surgery for tumor removal, particularly with near-infrared fluorescent imaging, is a potential method to facilitate removing all neoplastic tissue at the surgical site. In this study we demonstrate a series of hyaluronic acid (HLA)-derived nanoparticles that entrap the near-infrared dye indocyanine green, termed NanoICG, for improved delivery of the dye to tumors. Self-assembly of the nanoparticles was driven by conjugation of one of three hydrophobic moieties: aminopropyl-1-pyrenebutanamide (PBA), aminopropyl-5β-cholanamide (5βCA), or octadecylamine (ODA). Nanoparticle self-assembly, dye loading, and optical properties were characterized. NanoICG exhibited quenched fluorescence that could be activated by disassembly in a mixed solvent. NanoICG was found to be nontoxic at physiologically relevant concentrations and exposure was not found to inhibit cell growth. Using an MDA-MB-231 tumor xenograft model in mice, strong fluorescence enhancement in tumors was observed with NanoICG using a fluorescence image-guided surgery system and a whole-animal imaging system. Tumor contrast with NanoICG was significantly higher than with ICG alone.

Cartilage repair presents a daunting challenge in tissue engineering applications due to the low oxygen conditions (hypoxia) affiliated in diseased states. Hence, the use of biomaterial scaffolds with unique variability is imperative to treat diseased or damaged cartilage. Thermosensitive hydrogels show promise as injectable materials that can be used as tissue scaffolds for cartilage tissue regeneration. However, uses in clinical applications are limited to due mechanical stability and therapeutic efficacy to treat diseased tissue. In this study, several composite hydrogels containing poly(N-vinylcaprolactam) (PVCL) and methacrylated hyaluronic acid (meHA) were prepared using free radical polymerization to produce PVCL-graft-HA (PVCL-g-HA) and characterized using Fourier transform infrared spectroscopy, nuclear magnetic resonance, and scanning electron microscopy. Lower critical solution temperatures and gelation temperatures were confirmed in the range of 33-34°C and 41-45°C, respectively. Using dynamic sheer rheology, the temperature dependence of elastic (G') and viscous (G″) modulus between 25°C and 45°C, revealed that PVCL-g-HA hydrogels at 5% (w/v) concentration exhibited the moduli of 7 Pa (G') to 4 Pa (G″). After 10 days at 1% oxygen, collagen production on PVCL-g-HA hydrogels was 153 ± 25 μg/mg (20%) and 106 ± 18 μg/mg showing a 10-fold increase compared to meHA controls. These studies show promise in PVCL-g-HA hydrogels for the treatment of diseased or damaged articular cartilage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 1863-1873, 2017.

Summary: Anion metathesis enabled a systematic study focused on the thermal, viscoelastic, and conductivity properties of a 4P,12 phosphonium ionenes with various counterions. Aqueous size exclusion chromatography confirmed the well-defined synthesis of 4P,12-Br from the step-growth polymerization of 1,4-bis(diphenylphosphino) butane and 1,12-dibromododecane at a 1:1 stoichiometric ratio. Subsequent anion-exchange employing a dialysis method exchanged the Br -counterion to trifluoromethanesulfonate (TfO H nuclear magnetic resonance spectroscopy of the 4P,12 ionenes showed a distinct upfield chemical shift for methylene protons adjacent to the phosphonium cation after anion-exchange. Thermal characterization using thermogravimetric analysis and differential scanning calorimetry probed the thermal properties of the phosphonium ionenes. Counterion exchange to more bulky and delocalized anions led to improved thermal stabilities and lower glass transition temperatures. Rheological characterization facilitated the generation of timetemperature superposition (TTSp) master curves and pseudo-master curves for each 4P,12 ionene. TTSp revealed two distinct relaxation modes attributed to long-range segmental motion and electrostatic interactions. Anion-exchange resulted in a shift of these two modes of relaxation to higher shear rates. The calculated melt flow activation energy and thermal expansion coefficients were also observed to decrease and increase, respectively. Melt rheological characterization also probed the temperature dependence of the storage and loss moduli and suggested that the counterions have a plasticizing effect on the viscoelasticity of the 4P,12 ionene. Ionic conductivity increased with increasing size of the counterion (Br -< BF 4 -< TfO -< Tf 2 N -) and demonstrated the viability of these novel materials as potential anionexchange ionomeric membranes.

Liquid chromatography at the critical condition (LCCC) is a high performance liquid chromatography (HPLC) technique that lies between size exclusion chromatography and adsorption‐based interaction chromatography, where the elution of polymers becomes independent of polymer molecular weight. At LCCC, the balance between the entropic exclusion and the enthalpic adsorption interactions between polymers and stationary phases results in the simultaneous HPLC elution of polymers regardless of molecular weight. Using C18‐bonded silica chromatographic columns with 5 μm particle size and different average pore size (diameter = 300 Å, 120 Å, 100 Å, and 50 Å), we report (1) the thermodynamic significance of LCCC conditions and (2) the influence of column pore size on the determination of critical conditions for linear polymer chains. Specifically, we used mixtures of monodisperse polystyrene samples ranging in molecular weight from 162 to 371,100 g/mol and controlled the temperature of the HPLC columns at a fixed composition of a mobile phase consisting of 57(v/v)% methylene chloride and 43(v/v)% acetonitrile. It was found that, at the fixed mobile phase composition, the temperature of LCCC (TLCCC) is higher for C18‐bonded chromatographic columns with larger average pore size. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 2533–2540, 2009

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