Self-assembled thermosensitive luminescent nanoparticles with peptide-Au conjugates for cellular imaging and drug delivery

A facile and efficient strategy has been developed to fabricate a multifunctional,theranostic anticancer drug delivery platform featuring active targeting,controlled drug release and fluorescence imaging for real-time control of delivery.To this end,thermo sensitive poly(N-isopropyl acrylamide)(PNIPAM)nanospheres are decorated with peptide-Au cluster conjugates as a smart nanomedicine platform.A sophisticated trifunctional peptide is designed to release the anticancer drug doxorubicin(DOX),target cells and reduce Au^3+ions to form luminescent Au cluste rs.Importantly,the peptide-Au cluster moieties are attached to the PNIPAM nanospheres via amide bonds rather than noncovalent interactions,significantly improving their stability in biological medium and drug release efficiency.The in vitro experiments showed that DOX was released in an efficient and controlled manner under physiological conditions.

Highly Luminescent Positively Charged Quantum Dots Interacting with Proteins and Cells

We have studied interactions between positively charged MUTAB-stabilized quantum dots(QDs)and model proteins,serum and live cells using fluorescence correlation spectroscopy(FCS),dynamic light scattering(DLS),time-resolved photoluminescence(PL)and live-cell fluorescence imaging.Using human serum albumin(HSA)as a model protein,we measured the growth of a protein adsorption layer(“protein corona”)via time-resolved FCS.Corona formation was characterized by an apparent equilibrium dissociation coefficient,KD≈10μM.HSA adlayer growth was surprisingly slow(timescale ca.30 min),in stark contrast to many similar measurements with HSA and other proteins and different NPs.Time-resolved PL data revealed a characteristic quenching behavior depending on the QD surface coverage with HSA.Taken together,we found that MUTAB-QDs initially bind HSA molecules weakly(KD≈700μM);however,the affinity is enhanced over time,presumably due to proton injection into the MUTAB layer by HSA triggering ligand dissociation.This process was also observed with human blood serum,showing equal kinetics for comparable HSA concentration.Moreover,imaging experiments with cultured human cells(HeLa)revealed that MUTAB-QDs bind to the cell membrane and perforate it.This process is reduced upon pre-adsorption of proteins on the MUTAB-QD.