Amyloid‐like peptide nanofibrils (PNFs) are abundant in nature providing rich bioactivities and playing both functional and pathological roles. The structural features responsible for their unique bioactivities are, however, still elusive. Supramolecular nanostructures are notoriously challenging to optimize, as sequence changes affect self‐assembly, fibril morphologies, and biorecognition. Herein, the first sequence optimization of PNFs, derived from the peptide enhancing factor‐C (EF‐C, QCKIKQIINMWQ), for enhanced retroviral gene transduction via a multiparameter and a multiscale approach is reported. Retroviral gene transfer is the method of choice for the stable delivery of genetic information into cells offering great perspectives for the treatment of genetic disorders. Single fibril imaging, zeta potential, vibrational spectroscopy, and quantitative retroviral transduction assays provide the structure parameters responsible for PNF assembly, fibrils morphology, secondary and quaternary structure, and PNF‐virus‐cell interactions. Optimized peptide sequences such as the 7‐mer, CKFKFQF, have been obtained quantitatively forming supramolecular nanofibrils with high intermolecular β‐sheet content that efficiently bind virions and attach to cellular membranes revealing efficient retroviral gene transfer.

There is an urgent need for biomaterials that support tissue healing, particularly neuronal regeneration. In a medium throughput screen novel self-assembling peptide (SAP) sequences that form fibrils and stimulated nerve fiber growth of peripheral nervous system (PNS)-derived neurons are identified. Based on the peptide sequences and fibril morphologies and by applying rational data-mining, important structural parameters stimulating neuronal activity are elucidated. Three SAPs (SAP 1e , SAP 2e , and SAP 5c ) enhance adhesion and growth of PNS neurons. These SAPs form 2D and 3D matrices that serve as bioactive scaffolds stimulating cell adhesion and growth. The newly discovered SAPs also support the growth of CNS neurons and glia cells. Subsequently, the potential of SAPs to enhance PNS regeneration in vivo is analyzed. For this, the facial nerve driving whisker movement in mice is injured. Notably, SAPs persist for up to 3 weeks in the injury site indicating highly adhesive properties and stability. After SAP administration, more motor neurons incorporating markers for successive regeneration are observed. Recovery of whisker movement is elevated in SAP-injected mice. In summary, short peptides that form fibrils are identified and the adhesion, growth, and regeneration of neurons have been efficiently enhanced without the necessity to attach hormones or growth factors.

The synthesis of hybrid hydrogels by pH‐controlled structural transition with exceptional rheological properties as cellular matrix is reported. “Depsi” peptide sequences are grafted onto a polypeptide backbone that undergo a pH‐induced intramolecular O–N–acyl migration at physiological conditions affording peptide nanofibers (PNFs) as supramolecular gelators. The polypeptide–PNF hydrogels are mechanically remarkably robust. They reveal exciting thixotropic behavior with immediate in situ recovery after exposure to various high strains over long periods and self‐repair of defects by instantaneous reassembly. High cytocompatibility, convenient functionalization by coassembly, and controlled enzymatic degradation but stability in 2D and 3D cell culture as demonstrated by the encapsulation of primary human umbilical vein endothelial cells and neuronal cells open many attractive opportunities for 3D tissue engineering and other biomedical applications.

Hybrid nanomaterials have shown great potential in regenerative medicine due to the unique opportunities to customize materials properties for effectively controlling cellular growth. The peptide nanofiber-mediated auto-oxidative polymerization of dopamine, resulting in stable aqueous dispersions of polydopamine-coated peptide hybrid nanofibers, is demonstrated. The catechol residues of the polydopamine coating on the hybrid nanofibers are accessible and provide a platform for introducing functionalities in a pH-responsive polymer analogous reaction, which is demonstrated using a boronic acid modified fluorophore. The resulting hybrid nanofibers exhibit attractive properties in their cellular interactions: they enhance neuronal cell adhesion, nerve fiber growth, and growth cone area, thus providing great potential in regenerative medicine. Furthermore, the facile modification by pH-responsive supramolecular polymer analog reactions allows tailoring the functional properties of the hybrid nanofibers in a reversible fashion.

Retroviral gene transfer is the method of choice for the stable introduction of genetic material into the cellular genome. However, efficient gene transfer is often limited by low transduction rates of the viral vectors. We have recently described a 12-mer peptide, termed EF-C, that forms amyloid-like peptide nanofibrils (PNF), strongly increasing viral transduction efficiencies. These nanofibrils are polycationic and bind negatively charged membranes of virions and cells, thereby overcoming charge repulsions and resulting in increased rates of virion attachment and gene transfer. EF-C PNF enhance vector transduction more efficiently than other soluble additives and offer prospects for clinical applications. However, while the transduction-enhancing activity of PNF has been well-characterized, the exact mechanism and the kinetics underlying infection enhancement as well as the cellular fate of the fibrils are hardly explored. This is partially due to the fact that current labeling techniques for PNF rely on amyloid probes that cause high background staining or lose signal intensities after cellular uptake. Here, we sought to generate EF-C PNF covalently coupled with fluorescent labels. To achieve such covalent bioconjugates, the free amino groups of the EF-C peptide were coupled to the ATTO 495 or 647N NHS ester dyes. When small amounts of the labeled peptides were mixed with a 100- to 10 000-fold excess of the native peptide, PNF formed that were morphologically indistinguishable from those derived from the unlabeled peptide. The fluorescence of the fibrils could be readily detected using fluorescence spectroscopy, microscopy, and flow cytometry. In addition, labeled and nonlabeled fibrils captured viral particles and increased retroviral transduction with similar efficacy. These covalently fluorescence-labeled PNF are valuable tools with which to elucidate the mechanism(s) underlying transduction attachment and the fate of the fibrils in cells, tissues, and animal models.

Amyloid-like peptide nanofibrils (PNFs) are abundant in nature providing rich bioactivities and playing both functional and pathological roles. The structural features responsible for their unique bioactivities are, however, still elusive. Supramolecular nanostructures are notoriously challenging to optimize, as sequence changes affect self-assembly, fibril morphologies and biorecognition. Herein, we report the first sequence optimization of PNFs for enhanced retroviral gene transduction via a multiparameter and a multiscale approach. Retroviral gene transfer is the method of choice for stable delivery of genetic information into cells offering great perspectives for the treatment of genetic disorders. Single fibril imaging, zeta potential, vibrational spectroscopy and quantitative retroviral transduction assays provided the structure parameters responsible for PNF assembly, fibril morphologies and PNF-virus-cell interactions. Optimized peptide sequences have been obtained quantitatively forming supramolecular nanofibrils with high intermolecular beta-sheet content that efficiently bound virions and attached to cellular membranes revealing efficient retroviral gene transfer

Acute myeloid leukemia (AML) is characterized by relapse and treatment resistance in a major fraction of patients, underlining the need of innovative AML targeting therapies. Here we analysed the therapeutic potential of an innovative biohybrid consisting of the tumor-associated peptide somatostatin and the photosensitizer ruthenium in AML cell lines and primary AML patient samples. Selective toxicity was analyzed by using CD34 enriched cord blood cells as control. Treatment of OCI AML3, HL60 and THP1 resulted in a 92, and 99 and 97% decrease in clonogenic growth compared to the controls. Primary AML cells demonstrated a major response with a 74 to 99% reduction in clonogenicity in 5 of 6 patient samples. In contrast, treatment of CD34 + cB cells resulted in substantially less reduction in colony numbers. Subcellular localization assays of RU-SST in OCI-AML3 cells confirmed strong co-localization of RU-SSt in the lysosomes compared to the other cellular organelles. our data demonstrate that conjugation of a Ruthenium complex with somatostatin is efficiently eradicating LSc candidates of patients with AML. this indicates that receptor mediated lysosomal accumulation of photodynamic metal complexes is a highly attractive approach for targeting AML cells. Acute myeloid leukemia (AML) is initiated and propagated by cancer stem cells. Although these leukemic stem cells (LSCs) initially respond to chemotherapy, most patients relapse and die from the disease 1. One explanation is that current therapies only eliminate the tumor bulk which lacks leukemic stem cell properties whereas the LSCs are relatively insensitive. Growing knowledge of the molecular landscape of AML has led to clinical testing of new drugs against driver mutations as well as antibody-based therapies against cell surface proteins with partly disappointing results 2-5. Thus, for the majority of patients there is therapeutic standstill and the urgent need for innovative treatment approaches. Tumor-associated peptides provide attractive characteristics for AML-targeted strategies such as easy availability, convenient purification and storage. In addition, they are less immunogenic, have a high tissue penetration and a high affinity to cellular biomarkers. They provide a rapid clearance from the body and are excellent candidates for straight forward conjugation strategies. It has been shown that somatostatin receptors (SSTR) are expressed on leukemias such as T-cell leukemia and AML 6,7. Using a somatostatin radiobinding assay it was demonstrated that around 12.5% of AML cases express somatostatin receptors 6. Previously, it has been shown that primary AML progenitor cells, characterized by the co-expression of CD34 and CD117 express the somatostatin receptor (SSTR) subtype 2 and that the expression of the SSTR2 receptor was not restricted to the immature CD34 + CD117 + compartment, but also detected on more differentiated AML blasts. Using a transwell migration assay, it was demonstrated that the migration of AML cells towards a gradient

trans-Platinum(ii) oxadiazoline complexes with 7-nitro-1,3,5-triazaadamantane (NO-TAA) or hexamethylenetetramine (hmta) ligands have been synthesised from trans-[PtCl(PhCN)] via cycloaddition of nitrones to one of the coordinated nitriles, followed by exchange of the other nitrile by NO-TAA or hmta. Stoichiometric control allows for the selective synthesis of mono- and dinuclear complexes where 7-NOTAA and hmta act as mono- and bidentate ligands, respectively. Precursors and the target complexes trans-[PtCl(hmta)(oxadiazoline)], trans-[PtCl(NO-TAA)(oxadiazoline)] and trans-[{PtCl(oxadiazoline)}(hmta)] were characterised by elemental analysis, IR and multinuclear (H, C,Pt) NMR spectroscopy. DFT (B3LYP/6-31G*/LANL08) and AIM calculations suggest a stronger bonding of hmta with the [PtCl(oxadiazoline)] fragment, in agreement with the experimentally observed reactivity in the ligand exchange (hmta > 7-NOTAA). Replacement of the nitrile by hmta is predicted to be more exothermic than that with 7-NO-TAA, although the activation barriers are similar. Protonation of the non-coordinated N atoms is anticipated to weaken the Pt-N bond and lower the activation barrier for ligand exchange. This effect might help activate these compounds in a slightly acidic environment such as some tumour tissues. Ten of the new compounds were tested for their in vitro cytotoxicity in the human cancer cell lines HeLa and A549. Some of the mononuclear complexes are more potent than cisplatin, and their activity is still high in A549 where cisplatin shows little effect. The dinuclear complexes are inactive, presumably due to their lipophilicity and reduced solubility in water.