We generated a panel of single-domain antibodies targeting selected epitopes within tau, using the 'cascade method'. Briefly, we designed complementary peptides targeting linear epitopes within the sequence of tau using a library of beta-sheet fragments from the protein data bank. We then grafted each peptide into the CDR3 loop of a V H human scaffold. Using this approach, we produced a library of fourteen antibodies covering systematically the length of tau. We will use these antibodies to understand which epitopes are specifically exposed in toxic tau aggregates. In particular, we will employ them in superresolved imaging, such as DNA points accumulation for imaging in nanoscale topography (DNA PAINT), of protein aggregates. DNA PAINT enables visualization of structures with resolutions below the diffraction limit using short dye-labelled oligonucleotide probes. Transient binding of a dye-labelled 'imager strand' to a 'docking strand' (DS), which we conjugated to the C-terminus of DesAbs creates a blinking effect. Hence, a highly resolved image can be reconstructed from plotting the measured positions of the hydrolyzed DNA state. Using this technique to image protein aggregates in human cerebrospinal fluid and serum will provide novel insights into the composition, structure, size and number of aggregates present in those samples.

Dinitrogen coordination to iron centers underpins industrial and biological fixation in the Haber-Bosch process and by the FeM cofactors in the nitrogenase enzymes. The latter employ local high-spin metal centers; however, iron-dinitrogen coordination chemistry remains dominated by low-valent states, contrasting the enzyme systems. Here, we report a highspin mixed-valent cis-, where [L bis ] À is a bis(βdiketiminate) cyclophane. Field-applied Mössbauer spectra, dc and ac magnetic susceptibility measurements, and computational methods support a delocalized S = 7 / 2 Fe 2 N 2 unit with D = À 5.23 cm À 1 and consequent slow magnetic relaxation.Converting atmospheric dinitrogen into bioavailable forms (e.g., NH 3 ) is essential to life on Earth. However, scission of dinitrogen is a kinetically-limited reaction. [1] The Haber-Bosch process for industrial production of NH 3 employs the iron-based Mittasch catalyst and high temperatures and pressures to achieve reductive cleavage of N 2 . [2] Contrastingly, nitrogenase enzymes in biological systems effect N 2 reduction to NH 3 under ambient conditions utilizing Fe 7 M (M = Mo, V or Fe) cofactors with local high-spin Fe centers. [3] Whereas iron reactive sites in the Mittasch catalyst are predominantly in reduced states, [2] the nitrogenase cofactors are proposed to employ a cluster with minimal, if any, low valent iron character for N 2 conversion to NH 3 . [4][5][6][7]

Dinitrogen coordination to iron centers underpins industrial and biological fixation in the Haber-Bosch process and by the FeM cofactors in the nitrogenase enzymes. The latter employ local high-spin metal centers; however, iron-dinitrogen coordination chemistry remains dominated by low-valent states, contrasting the enzyme systems. Here, we report a highspin mixed-valent cis-, where [L bis ] À is a bis(βdiketiminate) cyclophane. Field-applied Mössbauer spectra, dc and ac magnetic susceptibility measurements, and computational methods support a delocalized S = 7 / 2 Fe 2 N 2 unit with D = À 5.23 cm À 1 and consequent slow magnetic relaxation.Converting atmospheric dinitrogen into bioavailable forms (e.g., NH 3 ) is essential to life on Earth. However, scission of dinitrogen is a kinetically-limited reaction. [1] The Haber-Bosch process for industrial production of NH 3 employs the iron-based Mittasch catalyst and high temperatures and pressures to achieve reductive cleavage of N 2 . [2] Contrastingly, nitrogenase enzymes in biological systems effect N 2 reduction to NH 3 under ambient conditions utilizing Fe 7 M (M = Mo, V or Fe) cofactors with local high-spin Fe centers. [3] Whereas iron reactive sites in the Mittasch catalyst are predominantly in reduced states, [2] the nitrogenase cofactors are proposed to employ a cluster with minimal, if any, low valent iron character for N 2 conversion to NH 3 . [4][5][6][7]