Laser micromachining technique offers a promising alternative method for rapid production of microfluidic devices. However, the effect of process parameters on the channel geometry and quality of channels on common microfluidic substrates has not been fully understood yet. In this research, we studied the effect of laser system parameters on the microchannel characteristics of Polydimethylsiloxane (PDMS), polymethyl methacrylate (PMMA), and microscope glass substrate—three most widely used materials for microchannels. We also conducted a cell adhesion experiment using normal human dermal fibroblasts on laser-machined microchannels on these substrates. A commercial CO₂ laser system consisting of a 45W laser tube, circulating water loop within the laser tube and air cooling of the substrate was used for machining microchannels in PDMS, PMMA and glass. Four laser system parameters—speed, power, focal distance, and number of passes were varied to fabricate straight microchannels. The channel characteristics such as depth, width, and shape were measured using a scanning electron microscope (SEM) and a 3D profilometer. The results show that higher speed produces lower depth while higher laser power produces deeper channels regardless of the substrate materials. Unfocused laser machining produces wider but shallower channels. For the same speed and power, PDMS channels were the widest while PMMA channels were the deepest. Results also showed that the profiles of microchannels can be controlled by increasing the number of passes. With an increased number of passes, both glass and PDMS produced uniform, wider, and more circular channels; in contrast, PMMA channels were sharper at the bottom and skewed. In rapid cell adhesion experiments, PDMS and glass microchannels performed better than PMMA microchannels. This study can serve as a quick reference in material-specific laser-based microchannel fabrications.

The most common bone cement material used clinically today for orthopedic surgery is poly(methyl methacrylate) (PMMA). Conventional PMMA bone cement has several mechanical, thermal, and biological disadvantages. To overcome these problems, researchers have investigated combinations of PMMA bone cement and several bioactive particles (micrometers to nanometers in size), such as magnesium oxide, hydroxyapatite, chitosan, barium sulfate, and silica. A study comparing the effect of these individual additives on the mechanical, thermal, and cell functional properties of PMMA would be important to enable selection of suitable additives and design improved PMMA cement for orthopedic applications. Therefore, the goal of this study was to determine the effect of inclusion of magnesium oxide, hydroxyapatite, chitosan, barium sulfate, and silica additives in PMMA on the mechanical, thermal, and cell functional performance of PMMA. American Society for Testing and Materials standard three-point bend flexural and fracture tests were conducted to determine the flexural strength, flexural modulus, and fracture toughness of the different PMMA samples. A custom-made temperature measurement system was used to determine maximum curing temperature and the time needed for each PMMA sample to reach its maximum curing temperature. Osteoblast adhesion and proliferation experiments were performed to determine cell viability using the different PMMA cements. We found that flexural strength and fracture toughness were significantly greater for PMMA specimens that incorporated silica than for the other specimens. All additives prolonged the time taken to reach maximum curing temperature and significantly improved cell adhesion of the PMMA samples. The results of this study could be useful for improving the union of implant-PMMA or bone-PMMA interfaces by incorporating nanoparticles into PMMA cement for orthopedic and orthodontic applications.

Electrospun nanofiber mesh has previously been used as an air filtration device. However, the qualification of polycaprolactone (PCL) nanofiber mesh cloth in face masks to protect individuals against airborne particles carrying microorganisms has yet to be investigated. The long-term goal of this study is to develop methods to use PCL nanofiber mesh to provide better protection against microorganisms. To achieve this goal, we observed the morphology, water droplet absorption, thermal (differential scanning calorimetry), mechanical, and airborne particle filtering capabilities, and also the microbial activities of a PCL cloth, to evaluate whether it is suitable to act as a filter in a face mask. We have produced a polycaprolactone (PCL) nanofiber cloth after electrospinning it onto a drum for 3 and 10 min, referred to hereafter as PCL-3 and PCL-10, respectively. Our study found that the middle protection layer (control) of the Henry Schein Earloop Procedure Mask contains pores (average diameter = 5.72 ± 0.62 µm) which are 48 times larger than the diameter of a microorganism an average diameter of ~120 nanometers. However, PCL-10 nanofiber membranes show pores with an average diameter of 1.42 ± 0.34 µm. Our contact angle measurement tests found that all the samples were very hydrophobic (contact angle values varied between 120 and 150 degrees). However, both PCL cloths’ contact angle values were lower compared to the control. The produced PCL cloths showed a lower water droplet absorption compared to the control. Thermal studies found that PCL is stable in extreme conditions and no plasticizing effect occurs due to the presence of a solvent. Mechanical tests showed that PCL-10 cloth had higher strength and modulus compared to the control and PCL-3 under tension loading conditions. A vacuum experiment found that the PCL-10 fiber cloth could withstand a negative pressure of 18 Psi without any signs of breakage, and the mask was able to capture airborne particles and microorganisms. The feasibility of immobilizing anti-bacterial nanoparticles with PCL during electrospinning creates the future potential of producing an anti-bacterial face mask using PCL.

Polyethylene Glycol Diacrylate (PEGDA) tissue scaffolds having a thickness higher than 1 mm and without the presence of nutrient conduit networks were shown to have limited applications in tissue engineering due to the inability of cells to adhere and migrate within the scaffold. The PEGDA scaffold has been coated with polycaprolactone (PCL) electrospun nanofiber (ENF) membrane on both sides to overcome these limitations, thereby creating a functional PEGDA-PCL scaffold. This study examined the physical, mechanical, and biological properties of the PEGDA and PEGDA-PCL scaffolds to determine the effect of PCL coating on PEGDA. The physical characterization of PEGDA-PCL samples demonstrated the effectiveness of combining PCL with a PEGDA scaffold to expand its applications in tissue engineering. This study also found a significant improvement of elasticity of PEGDA due to the addition of PCL layers. This study shows that PEGDA-PCL scaffolds absorb nutrients with time and can provide an ideal environment for the survival of cells. Furthermore, cell viability tests indicate that the cell adhered, proliferated, and migrated in the PEGDA-PCL scaffold. Therefore, PCL ENF coating has a positive influence on PEGDA scaffold.

Implant failure due to poor integration of the implant with the surrounding biomaterial is a common problem in various orthopedic and orthodontic surgeries. Implant fixation mostly depends upon the implant surface topography. Micron to nanosize circular-shaped groove architecture with adequate surface roughness can enhance the mechanical interlock and osseointegration of an implant with the host tissue and solve its poor fixation problem. Such groove architecture can be created on a titanium (Ti) alloy implant by laser peening treatment. Laser peening produces deep, residual compressive stresses in the surfaces of metal parts, delivering increased fatigue life and damage tolerance. The scientific novelty of this study is the controlled deposition of circular-shaped rough spot groove using laser peening technique and understanding the effect of the treatment techniques for improving the implant surface properties. The hypothesis of this study was that implant surface grooves created by controlled laser peen treatment can improve the mechanical and biological responses of the implant with the adjoining biomaterial. The objective of this study was to measure how the controlled laser-peened groove architecture on Ti influences its osteoblast cell functions and bonding strength with bone cement. This study determined the surface roughness and morphology of the peen-treated Ti. In addition, this study compared the osteoblast cell functions (adhesion, proliferation, and differentiation) between control and peen-treated Ti samples. Finally, this study measured the fracture strength between each kind of Ti samples and bone cement under static loading. This study found that laser peen treatment on Ti significantly changed the surface architecture of the Ti, which led to enhanced osteoblast cell adhesion and differentiation on Ti implants and fracture strength of Ti–bone cement interfaces compared with values of untreated Ti samples. Therefore, the laser peen treatment method has the potential to improve the biomechanical functions of Ti implants.