Acridine orange and silica nanoparticles facilitated novel robust fluorescent hollow microcapsules toward DNA bio-sensor

Fluorescence Sensing of Nucleic Acid by Curcumin Encapsulated Poly(Ethylene Oxide)-Block-Poly(Propylene Oxide)-Block-Poly(Ethylene Oxide) Based Nanocapsules

In a novel approach, curcumin has been encapsulated inside Poly(Ethylene Oxide)-Block-Poly(Propylene Oxide)-Block-Poly(Ethylene Oxide) (F108) nanocapsules. FTIR spectra have indicated a type of hydrogen bonding and dipole interaction between curcumin and F108. Fluorescence and UV-visible absorption profiles of curcumin in nanocapsules have indicated location of curcumin in more hydrophobic microenvironment. The relative fluorescence yield has increased by 6 times in the nanocapsules, which renders them as more sensitive probes to be used later on in sensing study. Therefore, based on the functionality of curcumin as a fluorescent transducer, encapsulated curcumin is used in biomedical application as DNA and RNA sensing. Detection limits are detected as 50 μM and 60 μM for DNA and RNA respectively. Linear dynamic concentration range obtained in this proposed method is much higher than reported in literature. The interaction between the nanocapsules and targeted DNA/RNA molecules is further approved by zeta potential studies. Furthermore, the real interaction of DNA with the encapsulated curcumin is confirmed by the interaction of the adenine and cytosine nucleotides. This has been verified through zeta potential measurements. Moreover, our prepared nanocapsules has presented a high percentage recovery of DNA and RNA (96-101%). Finally, stability results have illustrated a high photostability of encapsulated curcumin, indicating that proposed nanocapsules can be considered as a stable sensor during measurement time.

Smart Microcapsules with Molecular Polarity- and Temperature-Dependent Permeability

Microcapsules with molecule-selective permeation are appealing as microreactors, capsule-type sensors, drug and cell carriers, and artificial cells. To accomplish molecular size- and charge-selective permeation, regular size of pores and surface charges have been formed in the membranes. However, it remains an important challenge to provide advanced regulation of transmembrane transport. Here, smart microcapsules are designed that provide molecular polarity- and temperature-dependent permeability. With capillary microfluidic devices, water-in-oil-in-water (W/O/W) double-emulsion drops are prepared, which serve as templates to produce microcapsules. The oil shell is composed of two monomers and dodecanol, which turns to a polymeric framework whose continuous voids are filled with dodecanol upon photopolymerization. One of the monomers provides mechanical stability of the framework, whereas the other serves as a compatibilizer between growing polymer and dodecanol, preventing macrophase separation. Above melting point of dodecanol, molecules that are soluble in the molten dodecanol are selectively allowed to diffuse across the shell, where the rate of transmembrane transport is strongly influenced by partition coefficient. The rate is drastically lowered for temperatures below the melting point. This molecular polarity- and temperature-dependent permeability renders the microcapsules potentially useful as drug carriers for triggered release and contamination-free microreactors and microsensors.