Besides the resistance to fouling, the platform should be easily functionalized, i.e., conjugated with molecules having specific biological activity, usually a high affinity for specific targets. [9][10][11][12][13][14][15][16] Applications that require such functionalized antifouling platforms span from rapid detection of chemical and biological species, coatings of nanoparticles used in drug delivery, membranes for separation and cleaning technologies, to scaffolds for tissue engineering.Poly(carboxybetaine) (pCB) brushes are outstanding antifouling platforms allowing facile functionalization with biorecognition elements (BREs) via EDC/NHS (carbodiimide/N-hydroxysuccinimide) chemistry. [17][18][19] Their extraordinary properties stem from their high hydrophilicity and overall electroneutrality, which makes them resistant to hydrophobic as well as electrostatic adsorption from contacted media. However, their net electric charge is pH dependent. The positive charge of quaternary ammonium group is permanent but pKa of pCB carboxyl group is somewhere between 2 and 4. [17,20,21] The measurements of zeta potential of the surface bound poly(carboxybetaine methacrylamide) (pCBMAA), [22] indicated that its isoelectric point (pI) is around 8.5 and thus it is positively charged at lower pH values. The net positive charge of functionalized pCB brushes is further enhanced due to the consumption of betaine carboxyl groups following BRE conjugation reaction (Figure 1). It should be taken into consideration that conjugated BRE may also induce charge shifts and thus an effective optimization of the platform surface charge balance is of importance. [16] The overall reaction scheme for the BRE conjugation via EDC/NHS is shown in Figure 1. The carboxyl group of pCB is converted to active NHS ester which readily reacts with amino group of BRE to create stable amide bond. However, not all NHS esters buried inside pCB brushes are able to react with bulky BREs that cannot penetrate below the surface, but can react nonspecifically with other smaller amino compounds present in complex biological media. Therefore, all residual NHS esters must be eliminated (deactivated) as otherwise they could Poly(carboxybetaine) brushes are excellent antifouling platforms allowing facile functionalization with biorecognition elements via carbodiimide/N-hydroxysuccinimide (EDC/NHS) chemistry. However, residual active NHS esters and the loss of zwitterionic balance after the conjugation may impair initially excellent antifouling properties. This problem has so far been addressed either by using spontaneous hydrolysis or deactivation of residual NHS esters by the reaction with a small amino compound bearing hydroxyl or carboxyl groups. In contrast to this approach, and instead of using a single deactivator, here the use of tailored mixtures of deactivating agents containing carboxyl groups and sulfo or sulfate groups with permanent negative charge that allow to tune surface charge balance is investigated. The approach is applied to poly(carboxybetaine acr...

The current COVID-19 pandemic has become a worldwide problem with more than 169 million people infected by May 2021. Here we demonstrate a unique technology, based on the quartz crystal microbalance method, for the rapid detection of SARS-CoV-2. This biosensor fulfils all of the many requirements for the rapid detection of SARS-CoV-2 in complex samples. This is achieved by a tailored antifouling surface post-modified with antibodies against SARS-CoV-2 nucleocapsid protein (N). The A-QCM profits from absence of sample pre-treatment and utilizes the natural properties of N protein, which forms complexes with vRNA. Thanks to this, the clinically relevant LOD of 6.7×10 3 PFU/mL was reached using one-step detection assay. The A-QCM biosensor was also validated with clinical samples (i.e. nasopharyngeal swabs) with full agreement with qRT-PCR. The A-QCM biosensor was also utilized for the presence of SARS-CoV-2 in surface swabs in means of public transport.

The physical, thermal, structural, and mechanical properties of poly(methyl methacrylate) PMMA foils cast from solutions of toluene were investigated by differential scanning calorimetry, optical microscope, Fourier infrared spectroscopy, and dynamical mechanical analysis. The PMMA foils were prepared from a different ratio of PMMA powder with toluene solvent by the solution cast method. The surface features, glass transition temperature, and C-H bonds of foils were investigated and compared with commercial PMMA foil. The mechanical characterization of foils was examined by using static and dynamic loads in axial and transverse modes. The tensile behaviors of the commercial and as-prepared foils were investigated by using a strain rate of 0.01/s. The dynamical behavior of the foils was tested in tensile mode using 0.1 N of stress with a frequency of 1 Hz for the determination of storage, loss modulus, and damping values of the tan delta. A significant shape memory was observed in all of the prepared PMMA foils. The solution cast method allows for tuning the glass transition temperature of polymer foil that could easily integrate with the NiTi alloy phase transition temperature to fabricate a suitable composite structure. Integrating both structures will open the flexibility in bistable actuators in composite structures as a function of thermal cycles.

Star-shaped porphyrin-PNIPAM 4 (PP) conjugates having four PNIPAM arms connected to a central tetraphenylporphyrin unit were synthesized using reversible addition−fragmentation chain-transfer polymerization. Temperature-induced phaseseparation behavior of the conjugates was investigated, and the lower critical solution temperature (type II)−composition phase diagram was constructed using Flory−Huggins theory. Interestingly, in contrast to PNIPAM homopolymers, the shorter PNIPAM arms of PP conjugates lead to a lower phase-separation temperature (T p ). The concentration dependency of the size of the cooperative domain was also determined. Below T p , experimental data indicate that PP behaves as a 1D supramolecular polymer with a concentration-dependent length, while above T p , PP globules adopt a larger spherical shape. Various temperature− pH reversible and irreversible interdependencies ("cross-effects") between phase separation and protonation were observed. The PP conjugates represent a dual temperature−pH-responsive model system possessing various aggregated states, making them candidates for visual indicators, pH or temperature sensors, or singlet oxygen generators for biomedical applications.