Monitoring the Formation of Amyloid Oligomers Using Photoluminescence Anisotropy.

The formation of oligomeric soluble aggregates is related to the toxicity of amyloid peptides and proteins. In this manuscript, we report the use of a ruthenium polypyridyl complex ([Ru(bpy)2(dpqp)]2+) to track the formation of amyloid oligomers at different times using photoluminescence anisotropy. This technique is sensitive to the rotational correlation time of the molecule under study, which is consequently related to the size of the molecule. [Ru(bpy)2(dpqp)]2+ presents anisotropy values of zero when free in solution (due to its rapid rotation and long lifetime) but larger values as the size and concentration of amyloid-ß (Aß) oligomers increase. Our assays show that Aß forms oligomers immediately after the assay is started, reaching a steady state at ∼48 h. SDS-PAGE, DLS, and TEM were used to confirm and characterize the formation of oligomers. Our experiments show that the rate of formation for Aß oligomers is temperature dependent, with faster rates as the temperature of the assay is increased. The probe was also effective in monitoring the formation of α-synuclein oligomers at different times.

Near-Infrared Light Activates Molecular Nanomachines to Drill into and Kill Cells.

Using two-photon excitation (2PE), molecular nanomachines (MNMs) are able to drill through cell membranes and kill the cells. This avoids the use of the more damaging ultraviolet light that has been used formerly to induce this nanomechanical cell-killing effect. Since 2PE is inherently confocal, enormous precision can be realized. The MNMs can be targeted to specific cell surfaces through peptide addends. Further, the efficacy was verified through a controlled opening of synthetic bilayer vesicles using the 2PE excitation of MNM that had been trapped within the vesicles.

Microfluidic system for synthesis of nanofibrous conductive hydrogel and muscle differentiation.

Microscale hydrogels can be synthesized within microfluidic systems and subsequently assembled to make tissues composed of units such as myofibers in muscle tissue. Importantly, the nanofibrous surface of hydrogels is essential for tissue engineering aims due to inducing beneficial cell-surface interactions. In this study, a new microfluidic platform, embedded with a hydrogel, was introduced that allowed for performing multiple non-parallel steps for the synthetic approaches. Satellite cells, isolated from skeletal tissues of 10-day Naval Medical Research Institute-murine were cultured on the prepared hydrogel within the microfluidic system. The normal proliferation of satellite cells occurred after the employment of continuous perfusion cell culture. Interestingly, the positive results of the immuno-staining assay along with the cellular bridge formation between hydrogel fragments confirmed the muscle differentiation of seeded satellite cells. Further on, COMSOl simulations anticipated that the thermodynamic conditions of the microfluidic system during hydrogel synthesis had to be kept steady while a shear stress value of 15 × 10-6 Pa was calculated, exhibiting a cell culture condition free of environmental stress.

Soft-Lithographic Patterning of Luminescent Carbon Nanodots Derived from Collagen Waste.

Luminescent carbon dots (Cdots) synthesized using inexpensive precursors have inspired tremendous research interest because of their superior properties and applicability in various fields. In this work, we report a simple, economical, green route for the synthesis of multifunctional fluorescent Cdots prepared from a natural, low-cost source: collagen extracted from animal skin wastes. The as-synthesized metal-free Cdots were found to be in the size range of ∼1.2-9 nm, emitting bright blue photoluminescence with a calculated Cdot yield of ∼63%. Importantly, the soft-lithographic method used was inexpensive and yielded a variety of Cdot patterns with different geometrical structures and significant cellular biocompatibility. This novel approach to Cdot production highlights innovative ways of transforming industrial biowastes into advanced multifunctional materials which offer exciting potential for applications in nanophotonics and nanobiotechnology using a simple and scalable technique.