Effective cell number monitoring throughout the three-dimensional (3D) scaffold is a key factor in tissue engineering. There are many methods developed to evaluate cell number in 2D environments; however, they often encounter limitations in 3D. Therefore, there is a demand for reliable methods to measure cell proliferation in 3D surroundings. Here, we report a novel technique for the DNA content-based evaluation of cell proliferation using DNA-binding dye DAPI. We demonstrated the method’s compatibility with four different cell cultures: cancer lines MCF-7 and MH-22a, embryonic fibroblast cell line Swiss 3T3, and primary mesenchymal stem cell culture isolated from rat’s incisors. The DAPI based method was able to successfully evaluate cell proliferation in 2D, 2.5D, and 3D environments. Even though the proposed method does not discriminate between viable and dead cells, it might give a convenient snapshot of the cell number at a given time point. This should help to more reliably evaluate various processes proceeding in 2.5D and 3D cultures.

Metal ions are associated with a variety of proteins and play critical roles in a wide range of biochemical processes. There are multiple ways to study and quantify protein–metal ion interactions, including molecular dynamics simulations. Recently, the AMBER molecular mechanics forcefield was modified to include a 12-6-4 Lennard-Jones potential, which allows for a better description of nonbonded terms through the additional pairwise C_ij coefficients. Here, we demonstrate a method of generating C_ij parameters that allows parametrization of specific metal ion-ligating groups in order to tune binding energies computed by thermodynamic integration. The new C_ij coefficients were tested on a series of chelators: ethylenediaminetetraacetic acid, nitrilotriacetic acid, egtazic acid, and the EF1 loop peptides from the proteins lanmodulin and calmodulin. The new parameters show significant improvements in computed binding energies relative to existing force fields and produce coordination numbers and ion-oxygen distances that are in good agreement with experimental values. This parametrization method should be extensible to a range of other systems and could be readily adapted to tune properties other than binding energies.

SignificanceDental implants (DI) are among the most effective solutions for restoring masticatory function in patients with tooth loss. The success of these implants often depends on selecting appropriate design parameters, such as length and diameter, to ensure optimal outcomes. Understanding how these variables influence load transfer to the surrounding bone is essential for improving DI performance.AimWe aimed to evaluate the effects of implant diameter and length on static load distribution to surrounding bone-mimicking material (BMM) under identical optical and mechanical conditions, using an original and more accurate photoelastic testing method.ApproachEpoxy resin was used to replicate the mechanical behavior of the bone under static load conditions. A total of 12 DI designs with varying lengths and diameters were tested, with three replicas each (n=36). Polarized light was applied to the apex of each implant to detect optical intensity changes (ΔI) in the BMM under a 150-N static load and at rest.ResultsA significant correlation was found between implant diameter and load distribution (p0.05). The 6.9-mm diameter and longest implants transmitted the highest load to the BMM, whereas 11.5-mm length implants showed the lowest optical intensity changes (ΔI) under static load.ConclusionsImplant diameter has a greater impact than length on stress distribution to surrounding structures. Emphasizing diameter selection may enhance implant longevity and clinical success.