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We report that the aqueous self-assembly behavior of citrate based gold nanoparticles decorated with the temperature responsive RAFT-based polymer poly(N-isopropylacrylamide) critically depends on the presence of salt in the medium. Both for temperature induced reversible agglomeration and for hydrogen bonding based layer-by-layer assembly with tannic acid, the presence of salt dramatically promotes the assembly behavior. We attribute this to a combination of ionic screening of the remaining citrate groups on the nanoparticle surface and a salting out effect which increases the contribution of hydrophobic interactions in the self-assembly process. These findings provide new insights into an attractive class of polymer/gold hybrid nanomaterials that can find application in biotechnology, catalysis, and biomedicine.

The use of free-radical polymerization for the formation of an alkyne-functionalized polymer with ester units of polycaprolactone type in the backbone is shown. This is done by the copolymerization of a cyclic ketene acetal [2-methylene-1,3-dioxepane (MDO)] with propargyl acrylate using a free radical initiator, azobis(isobutyronitrile). Structural characterization of the copolymers using 1D and 2D NMR techniques shows the random distribution and very high percentage of inclusion of alkyne groups onto the polymer backbone. The exemplary grafting of a biocompatible polymer [poly(ethylene glycol)] via azide-alkyne "click" chemistry is also shown. Hydrolytic degradation behavior and biocompatibility of the polymers (cytotoxicity) studies are also reported. 1E-3 0,01 0,1 30 40 50 60 70 80 90 100 110 120 Cell viability (%) Concentration of polymer (mg/mL) 4a 4b 4c

Thermoresponsive PNIPAM coated AuNPs having dual stabilisation by the polymer chains and the charges, has been utilised for the development of temperature and salt sensors.

a Efficient polymer-protein conjugation is a crucial step in the design of many therapeutic protein formulations including nanoscopic vaccine formulations, antibody-drug conjugates and to enhance the in vivo behaviour of proteins. Here we aimed at preparing well-defined polymers for conjugation to proteins by reversible addition-fragmentation chain transfer (RAFT) polymerization of both acrylates and methacrylamides with protein-reactive chain transfer agents (CTAs). These RAFT agents contain either a N-hydroxysuccinimide (NHS) or pentafluorophenyl (PFP) ester moiety that can be conjugated to lysine residues, and alternatively a maleimide (MAL) or pyridyl disulfide (PDS) moiety that can be conjugated to cysteine residues. Efficiency of the bioconjugation of these polymers to bovine and avian serum albumin was investigated as a function of stoichiometry, polymer molecular weight and the presence of reducing agents. A large molar excess of polymer was required to obtain an acceptable degree of protein conjugation.However, protein modification with N-succinimidyl-S-acetylthiopropionate (SATP) to introduce sulfhydryl groups onto primary amines, significantly increased conjugation efficiency with MAL-and PDS-containing polymers.

In recent years, the layer-by-layer (LbL) assembly based on hydrogen bonding interactions is gaining popularity for the preparation of thin film coatings, especially for biomedical purposes, based on the use of neutral, non-toxic building blocks. The use of tannic acid (TA) as hydrogen bonding donor is especially interesting as it results in LbL films that are stable under physiological conditions. In this work, investigations on the LbL thin film preparation of TA with poly(2-oxazoline)s with varying hydrophilicity, namely poly(2-methyl-2-oxazoline) (PMeOx), poly(2-ethyl-2-oxazoline) (PEtOx) and poly(2-n-propyl-2-oxazoline) (PnPropOx), are reported. The LbL assembly process is investigated by quartz crystal microbalance and UV-vis spectroscopy revealing linear growth of the film thickness. Furthermore, isothermal titration calorimetry demonstrates the LbL assembly of TA, and PMeOx is found to be mostly enthalpy driven while the LbL assembly of TA with PEtOx and PnPropOx is mostly entropy driven. Finally, scanning electron microscopy and ellipsometry demonstrate the formation of smooth thin films for LbL assembly of TA with all three polymers. Such poly(2-oxazoline) coatings have high potential for use as anti-biofouling coatings.

Poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) has been reported to show both upper critical solution temperature (UCST) and lower critical solution temperature (LCST) behavior in presence of trivalent metal hexacyano anions, which is attractive for the development of smart materials. In this communication, the influence of the double thermoresponsive behavior of PDMAEMA driven by electrostatic interactions is investigated by comparing systems with [Co(CN)6 ](3-) , [Fe(CN)6 ](3-) , and [Cr(CN)6 ](3-) as trivalent anions. Furthermore, tuning of double thermoresponsive behavior of PDMAEMA by incorporating hydrophilic or hydrophobic comonomers is also discussed in the presence of [Fe(CN)6 ](3-) as trivalent ion.

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