4 research outputs found
Photosensitive Thin Films Based on Drop Cast and Langmuir-Blodgett Hydrophilic and Hydrophobic CdS Nanoparticles
Comparative photoelectrochemical studies of cadmium sulfide (CdS) nanoparticles with either hydrophilic or hydrophobic surface properties are presented. Oleylamine organic shells provided CdS nanoparticles with hydrophobic behavior, affecting the photoelectrochemical properties of such nanostructured semiconductor. Hydrophilic CdS nanoparticles were drop-cast on the electrode, whereas the hydrophobic ones were transferred in a controlled manner with Langmuir-Blodgett technique. The substantial hindrance of photopotential and photocurrent was observed for L-B CdS films as compared to the hydrophilic, uncoated nanoparticles that were drop-cast directly on the electrode surface. The electron lifetime in both hydrophilic and hydrophobic nanocrystalline CdS was determined, revealing longer carrier lifetime for oleylamine coated CdS nanoparticles, ascribed to the trapping of charge at the interface of the organic shell/CdS nanoparticle and to the dominant influence of the resistance of the organic shell against the flux of charges. The “on” transients of the photocurrent responses, observed only for the oleylamine-coated nanoparticles, were resolved, yielding the potential-dependent rate constants of the redox processes occurring at the interface
Biofabrication of 3D breast cancer models for dissecting the cytotoxic response of human T cells expressing engineered MAIT cell receptors.
Immunotherapy has revolutionized cancer treatment with the advent of advanced cell engineering techniques aimed at targeted therapy with reduced systemic toxicity. However, understanding the underlying immune-cancer interactions require development of advanced three-dimensional (3D) models of human tissues. In this study, we fabricated 3D tumor models with increasing complexity to study the cytotoxic responses of CD
Chemotherapeutics and CAR-T Cell-Based Immunotherapeutics Screening on a 3D Bioprinted Vascularized Breast Tumor Model
Despite substantial advancements in development of cancer treatments, lack of standardized and physiologically-relevant in vitro testing platforms limit the early screening of anticancer agents. A major barrier is the complex interplay between the tumor microenvironment and immune response. To tackle this, a dynamic-flow based 3D bioprinted multi-scale vascularized breast tumor model, responding to chemo and immunotherapeutics is developed. Heterotypic tumors are precisely bioprinted at pre-defined distances from a perfused vasculature, exhibit tumor angiogenesis and cancer cell invasion into the perfused vasculature. Bioprinted tumors treated with varying dosages of doxorubicin for 72 h portray a dose-dependent drug response behavior. More importantly, a cell based immune therapy approach is explored by perfusing HER2-targeting chimeric antigen receptor (CAR) modified CD8+ T cells for 24 or 72 h. Extensive CAR-T cell recruitment to the endothelium, substantial T cell activation and infiltration to the tumor site, resulted in up to ≈70% reduction in tumor volumes. The presented platform paves the way for a robust, precisely fabricated, and physiologically-relevant tumor model for future translation of anti-cancer therapies to personalized medicine
Raman Optical Activity Reveals Carotenoid Photoactivation Events in the Orange Carotenoid Protein in Solution
The
orange carotenoid protein (OCP) plays an important role in
photoprotection in cyanobacteria, which is achieved by the photoconversion
from the orange dark state (OCP<sup>O</sup>) to the red active state
(OCP<sup>R</sup>). Using Raman optical activity (ROA), we studied
the conformations of the carotenoid chromophore in the active sites
of OCP<sup>O</sup> and OCP<sup>R</sup>. This ROA measurement directly
observed the chromophore conformation of native OCP in solution, and
the measurement of OCP<sup>R</sup> first demonstrated the ROA spectroscopy
for the transient species. For OCP<sup>O</sup>, the spectral features
of ROA were mostly reproduced by the quantum chemical calculation
based on the crystal structure of the OCP. Within the spatial resolution
(∼2 Å), a slight modification of the polyene-chain distortion
improved the agreement between the observed and calculated ROA spectra.
While the crystal structure of OCP<sup>R</sup> is not available, the
ROA spectrum of OCP<sup>R</sup> was reproduced by using the crystal
structure of red carotenoid protein (RCP), an OCP<sup>R</sup> proxy.
The present results showed that the chromophore conformations in the
crystal structures of OCP and RCP hold true for OCP<sup>O</sup> and
OCP<sup>R</sup> in solution. Particularly, ROA spectroscopy of the
native OCP<sup>R</sup> provides a direct support for the 12 Å
translocation of chromophore in the photoactivation, which was proposed
by X-ray crystallography using RCP [R. L. Leverenz, M. Sutter, et
al. <i>Science</i> <b>2015</b>, 348, 1463–1466]