Conceptually new one-pot photoinduced sequential click reactions were implemented to yield novel block copolymers with the ability for cell adhesion. Poly(ε-caprolcatone) possessing clickable functional groups at the chain ends, namely α-alkynyl-ω-alkenyl-poly(ε-caprolactone) (A-PCL-MA), was prepared by ring-opening polymerization of ε-caprolactone using propargyl alcohol in the presence of stannous octoate at 110 °C followed by esterification with methacrylic acid. Azide-functional poly(methyl methacrylate) (PMMA-N3) was prepared independently by atom transfer radical polymerization (ATRP) followed by an azidation process using sodium azide. Finally, A-PCL-MA was reacted with PMMA-N3 and N-acetyl-l-cysteine (NAC) in a one-pot process through photoinduced sequential click reactions to furnish desired bioactive block copolymer (PMMA-b-PCL-NAC). A matrix for cell adhesion was then prepared from the yielded block copolymer PMMA-b-PCL-NAC and cell proliferation on the matrix was measured. Cells from the Vero cell line (African green monkey kidney epithelial) were incubated on the matrix, and after 48 h, they showed greater cell proliferation than the commercially available cell culture plates used as comparison.

Atom transfer radical polymerization (ATRP) and copper-catalyzed azide-alkyne cycloaddition (CuAAC) reactions, both utilizing copper(I) (Cu(I)) complexes, make a tremendous progress in synthetic polymer chemistry. Independently or in combination with other polymerization processes, they give access to the synthesis of polymers with well-defined structures, desired molecular architectures, and a wide variety of functionalities. Here, a novel in situ photoinduced formation of block copolymers is described by simultaneous ATRP and CuAAC processes. This approach relies on the direct reduction of initially charged copper(II) complexes to Cu(I) complexes to trigger both ATRP and CuAAC reactions coinciding under UV light at ambient temperature in one pot. Its synthetic utility is demonstrated on a model block copolymerization process by photoinduced ATRP of methyl methacrylate (MMA) using an initiator possessing acetylene functionality and concomitant click reaction between thus formed α-acetylene-poly(methyl methacrylate) (Ac-PMMA) and independently prepared azide functional polystyrene (PS-N ). Successful formation of PS-b-PMMA block copolymer is confirmed by FT-IR and H NMR spectral analysis and gel permeation chromatography (GPC) measurements.

N-Acetyl-l-cysteine (NAC)-capped poly(methyl methacrylate)-b-polycaprolactone block copolymer (PMMA-b-PCL-NAC) was prepared using the previously described one-pot photoinduced sequential CuAAC/thiol-ene double click procedure. PMMA-b-PCL-NAC had previously shown good applicability as a matrix for cell adhesion of cells from the Vero cell line (African green monkey kidney epithelial). Here, in this work, PMMA-b-PCL-NAC served as an excellent immobilization matrix for biomolecule conjugation. Covalent binding of RGD (R: arginine, G: glycine, and D: aspartic acid) peptide sequence onto the PMMA-b-PCL-NAC-coated surface was performed via EDC chemistry. RGD-modified PMMA-b-PCL-NAC (PMMA-b-PCL-NAC-RGD) as a non-toxic cell proliferation platform was used for selective "integrin αvβ3-mediated cell adhesion and biosensing studies. Both optical and electrochemical techniques were used to monitor the adhesion differences between "integrin αvβ3" receptor positive and negative cell lines on to the designed biofunctional surfaces.

In the present work, a novel photochemical approach based on visible light induced Type II photoinitiation for the preparation of clickable hydrogels is presented. Fluorescent pyrene groups were successfully incorporated onto the hydrogels via these clickable sites. Its synthetic validity for macromolecular synthesis is also demonstrated through a model photopolymerization process.

We present localization with stimulated emission depletion (LocSTED) microscopy, a combination of STED and single-molecule localization microscopy (SMLM). We use the simplest form of a STED microscope that is cost effective and synchronization free, comprising continuous wave (CW) lasers for both excitation and depletion. By utilizing the reversible blinking of fluorophores, single molecules of Alexa 555 are localized down to ~5 nm. Imaging fluorescently labeled proteins attached to nanoanchors structured by STED lithography shows that LocSTED microscopy can resolve molecules with a resolution of at least 15 nm, substantially improving the classical resolution of a CW STED microscope of about 60 nm. LocSTED microscopy also allows estimating the total number of proteins attached on a single nanoanchor.

Stimulated emission depletion (STED) nanolithography allows nanofabrication below the diffraction limit. Recently, it was applied to nanoanchors for protein fixation down to the single molecule level. We now combined STED nanolithography with laser-assisted protein adsorption by photobleaching (LAPAP) for optical and selective attachment of proteins to subdiffractional structures. In turn, STED was used for imaging of fluorescently tagged streptavidin to reveal protein binding to STED-lithographically patterned acrylate structures via LAPAP. Protein localization down to 56 nm spots was achieved using all-optical methods at visible wavelengths.

Laser-assisted protein adsorption by photobleaching (LAPAP) is a versatile tool to nanopattern proteins on the micrometer scale. Sub-micron patterning is, however, difficult due to diffraction. We show that, similar to stimulated emission depletion (STED) microscopy, a depleting beam can effectively suppress LAPAP and hence is apt to locally control LAPAP in order to write sub-diffractional lines of proteins. Specifically, we attach biotinylated Atto 390 to glass substrates and incubate with Alexa 555 labeled streptavidin. The Alexa 555 is subsequently imaged with STED nanoscopy. The method is currently limited by diffusion of the biotinylated Atto 390 molecules.

A novel synthetic strategy for the synthesis of block copolymers based on mechanistic transformation from photoinitiated cationic polymerization to radical addition fragmentation transfer polymerization is presented.