Nanoparticle based Tuberculosis vaccine

Despite the widespread use of Bacille de Calmette et Guérin (BCG) for over50 years, tuberculosis (TB) continues to be a major global health problem, especially in developing countries. Indeed BCG as been shown to reduce infant mortality, but demonstrated very high variability in preventing TB in adults. There is thus an urgent need for the development of an e-cacious novel TB vaccine that confirms long-term protection in both adult and children. A newnanoparticle (NP) delivery technology was recently developed in the laboratories of Prof. Swartz and Prof. Hubbell at the Swiss Federal Institute of Technology in Lausanne (EPFL) which proposes an innovative gene delivery approach for immunotherapy by targeting lymph node-residing dendritic cells (DCs). The NP platform has been shown to be extremely stable, safe, cheap, and able to induce strong T-cell responses and is thus expected to be a potential candidate for BCG replacement or BCG-prime booster. In this context we describe a preclinical testing plan that includes best formulation selection, dosage determination, e--cacy, and safety testing. We also explore regulatory issues, vaccine manufactory and the transition to clinical trials. Parralelly, better characterization of the NP platform itself is needed. The second part of this project is thus devoted to the study of NP surface modifications and their implications in the genera-tion of an immune response. Experiments using methoxylated and hydroxylated NPs suggest that free thiols present at the surface play a role in complement activation, however still poorly understood. In addition, N-terminal modified thiol-containing proteins have been synthesized for coupling on pyridyldisulfide NPs. This strategy greatly broadens the application of the NP platform, since it may be applied to almost any proteins. Finally thiol caging is reported as a method to recover thiols after antigen conjugatio

Fiber-optic protease sensor based on the degradation of thin gelatin films

Despite increasing interest in situ monitoring of proteolytic activity in chronic wound is not possible and information can only be obtained by sampling wound exudate. In this context, we developed an evanescent wave (EW) fiber-optic sensor to quantify protease activity directly in the wound bed. Detection is based on the degradation of thin gelatin films deposited on the fiber core by dip-coating, which serve as a substrate for proteases. After staining with a chlorophyllin copper sodium salt biocompatible dye, EW absorption occurs proportionally to the dye concentration, which is detected by the variation in light transmission intensity. The sensor response varies proportionally to enzymatic activity, showing sensitivity against MMP-2 and MMP-9 down to 2 μg/mL and 10 μg/mL, respectively. In addition, it is sensitive to film thickness and crosslink density, thus allowing tuning of the sensitivity and lifetime. Designed to be totally biocompatible and low cost, this miniature sensor has potential for use as a point-of-care disposable device in a clinical environment to assist physicians with quantitative information about the wound healing process

Biosensors Based on Porous Cellulose Nanocrystal–Poly(vinyl Alcohol) Scaffolds

Cellulose nanocrystals (CNCs), which offer a high aspect ratio, large specific surface area, and large number of reactive surface groups, are well suited for the facile immobilization of high density biological probes. We here report functional high surface area scaffolds based on cellulose nanocrystals (CNCs) and poly­(vinyl alcohol) (PVA) and demonstrate that this platform is useful for fluorescence-based sensing schemes. Porous CNC/PVA nanocomposite films with a thickness of 25–70 nm were deposited on glass substrates by dip-coating with an aqueous mixture of the CNCs and PVA, and the porous nanostructure was fixated by heat treatment. In a subsequent step, a portion of the scaffold’s hydroxyl surface groups was reacted with 2-(acryloxy)­ethyl (3-isocyanato-4-methylphenyl)­carbamate to permit the immobilization of thiolated fluorescein-substituted lysine, which was used as a first sensing motif, via nucleophile-based thiol–ene Michael addition. The resulting sensor films exhibit a nearly instantaneous and pronounced change of their fluorescence emission intensity in response to changes in pH. The approach was further extended to the detection of protease activity by immobilizing a Förster-type resonance energy transfer chromophore pair via a labile peptide sequence to the scaffold. This sensing scheme is based on the degradation of the protein linker in the presence of appropriate enzymes, which separate the chromophores and causes a turn-on of the originally quenched fluorescence. Using a standard benchtop spectrometer to monitor the increase in fluorescence intensity, trypsin was detected at a concentration of 250 μg/mL, i.e., in a concentration that is typical for abnormal proteolytic activity in wound fluids