Monitoring clinical levels of heparin in human blood samples with an indicator-displacement assay

We report that a "tree-like" polymer of lysine is able to form a multi-ligand complex with a fluorescently labelled peptide, leading to the almost complete extinction of the optical signal that can be restored upon the introduction of heparin. This simple system allows, for the first time, the turn-ON fluorescent sensing of the anticoagulant in human blood at clinically relevant levels.

Peptide and glycopeptide dendrimer apple trees as enzyme models and for biomedical applications

Solid phase peptide synthesis (SPPS) provides peptides with a dendritic topology when diamino acids are introduced in the sequences. Peptide dendrimers with one to three amino acids between branches can be prepared with up to 38 amino acids (MW ~ 5,000 Da). Larger peptide dendrimers (MW ~ 30,000) were obtained by a multivalent chloroacetyl cysteine (ClAc) ligation. Structural studies of peptide dendrimers by CD, FT-IR, NMR and molecular dynamics reveal molten globule states containing up to 50% of α-helix. Esterase and aldolase peptide dendrimers displaying dendritic effects and enzyme kinetics (k(cat)/k(uncat) ~ 10(5)) were designed or discovered by screening large combinatorial libraries. Strong ligands for Pseudomonas aeruginosa lectins LecA and LecB able to inhibit biofilm formation were obtained with glycopeptide dendrimers. Efficient ligands for cobalamin, cytotoxic colchicine conjugates and antimicrobial peptide dendrimers were also developed showing the versatility of dendritic peptides. Complementing the multivalency, the amino acid composition of the dendrimers strongly influenced the catalytic or biological activity obtained demonstrating the importance of the "apple tree" configuration for protein-like function in peptide dendrimers.

Turn-on room temperature phosphorescence assay of heparin with tunable sensitivity and detection window based on target-induced self-assembly of polyethyleneimine capped Mn-doped ZnS quantum dots

Room-temperature phosphorescence (RTP) turn-on assay of heparin with tunable sensitivity and detection window was demonstrated on the basis of the target induced self-assembly of polyethyleneimine capped Mn-doped ZnS (PEI-Mn-ZnS) QDs. The proposed method can cover the whole therapeutic dosing concentration range in postoperation and long-term therapy (0.2-1.2 U/mL, 1.7-10 μM) and cardiovascular surgery (2-8 U/mL, 17-67 μM) in 10 mM Tris-HCl (pH 7.4) buffer and can be applied for heparin determination in 100-fold diluted human serum samples. The tunable sensitivity and detection window was ascribed to the tunable particle size and ligand loading amount of PEI-Mn-ZnS QD arising from the chain length (or molecule weight) and feed amount of PEI. The chain length of PEI exhibited significant effect on the particle size and ligand loading amount and ultimately had important influence on both the sensitivity and detection window. The feeding amount of PEI, however, greatly affected the ligand loading amount alone and, in turn, affected only the detection window.