Nanostructured Oxygen Sensor - Using Micelles to Incorporate a Hydrophobic Platinum Porphyrin

Hydrophobic platinum(II)-5,10,15,20-tetrakis-(2,3,4,5,6-pentafluorophenyl)-porphyrin (PtTFPP) was physically incorporated into micelles formed from poly(ε-caprolactone)-block-poly(ethylene glycol) to enable the application of PtTFPP in aqueous solution. Micelles were characterized using dynamic light scattering (DLS) and atomic force microscopy (AFM) to show an average diameter of about 140 nm. PtTFPP showed higher quantum efficiency in micellar solution than in tetrahydrofuran (THF) and dichloromethane (CH2Cl2). PtTFPP in micelles also exhibited higher photostability than that of PtTFPP suspended in water. PtTFPP in micelles exhibited good oxygen sensitivity and response time. This study provided an efficient approach to enable the application of hydrophobic oxygen sensors in a biological environment

A general strategy for expanding polymerase function by droplet microfluidics.

Polymerases that synthesize artificial genetic polymers hold great promise for advancing future applications in synthetic biology. However, engineering natural polymerases to replicate unnatural genetic polymers is a challenging problem. Here we present droplet-based optical polymerase sorting (DrOPS) as a general strategy for expanding polymerase function that employs an optical sensor to monitor polymerase activity inside the microenvironment of a uniform synthetic compartment generated by microfluidics. We validated this approach by performing a complete cycle of encapsulation, sorting and recovery on a doped library and observed an enrichment of ∼1,200-fold for a model engineered polymerase. We then applied our method to evolve a manganese-independent α-L-threofuranosyl nucleic acid (TNA) polymerase that functions with >99% template-copying fidelity. Based on our findings, we suggest that DrOPS is a versatile tool that could be used to evolve any polymerase function, where optical detection can be achieved by Watson-Crick base pairing

Retention percentage of PtTFPP from PCL-<i>b</i>-PEG micelles.

<p>Retention percentage of PtTFPP from PCL-<i>b</i>-PEG micelles.</p

Response time studied through a saturation of air and nitrogen saturation to the micellar solutions (A) and through the consumption of the oxygen by the oxidation of glucose by glucose oxidase (B).

<p>Concentration of glucose was 0.25 M and the concentration of the glucose oxidase was 10 mg/mL.</p

Photostability of PtTFPP in PCL-<i>b</i>-PEG micelles (A) and PtTFPP suspended in 5% THF-containing HEPES buffer (B).

<p>Photostability of PtTFPP in PCL-<i>b</i>-PEG micelles (A) and PtTFPP suspended in 5% THF-containing HEPES buffer (B).</p

Typical oxygen sensing of the PtTFPP/PCL-<i>b</i>-PEG micelles excited at 390 nm (A).

<p>Stern-Volmer responses of the micelles excited at 390, 405, and 514 nm (B).</p

Chemical structures of PtTFPP and PCL-<i>b</i>-PEG and the schematic drawing of the micelle formation.

<p>Chemical structures of PtTFPP and PCL-<i>b</i>-PEG and the schematic drawing of the micelle formation.</p

Photophysical properties of PtTFPP in micelles, THF and CH₂Cl₂ solutions.

<p>Photophysical properties of PtTFPP in micelles, THF and CH₂Cl₂ solutions.</p

DLS of the micelles (A) and AFM image of the dried micelles (B).

<p>DLS of the micelles (A) and AFM image of the dried micelles (B).</p