The effect of surface roughness on the detachment between the bubbles and the glass beads (soda-lime) was comprehensively investigated. Glass beads with dimensions of −1.20 + 1.12 mm were acid etched to achieve varying degrees of surface roughness, followed by silanation reactions conducted for different immersion times. The characterization of surface roughness was conducted using a ContourGT-K 3D optical microscope. Measurements of receding contact angle, induction time and detachment force were conducted to assess the influence of surface roughness on bubble and glass bead attachment/detachment. It is observed that the etching surface of glass beads with uniform protrusions and depressions, the hydrophobic glass beads exhibited shorter induction time, larger contact angle and higher critical detachment force. However, the stability of aggregates of bubbles and hydrophilic glass beads was reduced, making them prone to detachment. Moreover, larger protrusions and depressions on hydrophobic glass bead surfaces with increasing etching time, resulted in an increase in induction time, a decrease in receding contact angle and critical detachment force. The stability of bubbles and hydrophilic glass bead aggregates remained unchanged.
Danle Lin,Ziyu Zhou,Mengdan Zhang,Songyou Yao,Lingling Yuan,Meng Xu,Xiaoyue Zhang,Xiaoli Hu
Biophysical and biochemical cues of biomaterials can regulate cell behaviors. Dental pulp stem cells (DPSCs) in pulp tissues can differentiate to odontoblast-like cells and secrete reparative dentin to form a barrier to protect the underlying pulp tissues and enable complete pulp healing. Promotion of the odontogenic differentiation of DPSCs is essential for dentin regeneration. The effects of the surface potentials of biomaterials on the adhesion and odontogenic differentiation of DPSCs remain unclear. Here, poly(vinylidene fluoride-trifluoro ethylene) (P(VDF-TrFE)) films with different surface potentials were prepared by the spin-coating technique and the contact poling method. The cytoskeletal organization of DPSCs grown on P(VDF-TrFE) films was studied by immunofluorescence staining. Using atomic force microscopy (AFM), the lateral detachment forces of DPSCs from P(VDF-TrFE) films were quantified. The effects of electrical stimulation generated from P(VDF-TrFE) films on odontogenic differentiation of DPSCs were evaluated in vitro and in vivo. The unpolarized, positively polarized, and negatively polarized films had surface potentials of −52.9, +902.4, and −502.2 mV, respectively. DPSCs on both negatively and positively polarized P(VDF-TrFE) films had larger cell areas and length-to-width ratios than those on the unpolarized films (P < 0.05). During the detachment of DPSCs from P(VDF-TrFE) films, the average magnitudes of the maximum detachment forces were 29.4, 72.1, and 53.9 nN for unpolarized, positively polarized, and negatively polarized groups, respectively (P < 0.05). The polarized films enhanced the mineralization activities and increased the expression levels of the odontogenic-related proteins of DPSCs compared to the unpolarized films (P < 0.05). The extracellular signal-regulated kinase (ERK) signaling pathway was involved in the odontogenic differentiation of DPSCs as induced by surface charge. In vivo, the polarized P(VDF-TrFE) films enhanced adhesion of DPSCs and promoted the odontogenic differentiation of DPSCs by electrical stimulation, demonstrating a potential application of electroactive biomaterials for reparative dentin formation in direct pulp capping.
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