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In the use of the medical devices, it is essential to prevent the attachment of bacteria to the device surface or to kill the attached bacteria. To kill bacteria, many researchers have used antibiotics or studied nanostructure-based antibacterial surfaces, which rely on mechanical antibacterial methods. Several polymers are widely used for device fabrication, one of which is polycaprolactone (PCL). PCL is biocompatible, biodegradable, easy to fabricate using 3D printing, relatively inexpensive and its quality is easily controlled; therefore, there are various approaches to its use in bio-applications. In addition, it is an FDA-approved material, so it is often used as an implantable material in the human body. However, PCL has no inherent antibacterial function, so it is necessary to develop antibacterial functions in scaffold or film-based PCL medical devices. In this study, process parameters for nanopillar fabrication were established through a simple thermal imprinting method with PCL. Finally, a PCL film with a flexible and transparent nanopillar structure was produced, and the mechano-bactericidal potential was demonstrated using only one PCL material. PCL with nanopillars showed bactericidal ability against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) bacteria cultured on its surface that resulted in membrane damage and death due to contact with nanopillars. Additionally, bacteriostatic results were shown to inhibit bacterial growth and activity of Staphylococcus aureus (S. aureus) on PCL nanostructured columns. The fabricated nanopillar structure has confirmed that mechanically induced antibacterial function and can be applied to implantable medical devices.

Among 3D-printed composite scaffolds for bone tissue engineering, researchers have been attracted to the use of zinc ions to improve the scaffold’s anti-bacterial activity and prevent surgical site infection. In this study, we assumed that the concentration of zinc ions released from the scaffold will be correlated with the thickness of the zinc oxide coating on 3D-printed scaffolds. We investigated the adequate thickness of zinc oxide coating by comparing different scaffolds’ characteristics, antibacterial activity, and in vitro cell response. The scaffolds’ compressive modulus decreased as the zinc oxide coating thickness increased (10, 100 and 200 nm). However, the compressive modulus of scaffolds in this study were superior to those of other reported scaffolds because our scaffolds had a kagome structure and were made of composite material. In regard to the antibacterial activity and in vitro cell response, the in vitro cell proliferation on scaffolds with a zinc oxide coating was higher than that of the control scaffold. Moreover, the antibacterial activity of scaffolds with 100 or 200 nm-thick zinc oxide coating on Escherichia coli was superior to that of other scaffolds. Therefore, we concluded that the scaffold with a 100 nm-thick zinc oxide coating was the most appropriate scaffold to use as a bone-regenerating scaffold, given its mechanical property, its antibacterial activity, and its in vitro cell proliferation.

In this paper, we explore the development of a multi-functional surface designed to tackle the challenges posed by Staphylococcus aureus (S. aureus), a common opportunistic pathogen. Infections caused by S. aureus during surgical procedures highlight the need for effective strategies to inhibit its adhesion, growth, and colonization, particularly on the surfaces of invasive medical devices. Until now, most existing research has focused on nanopillar structures (positive topographies). Uniform nanopillar arrays have been shown to control bacterial behavior based on the spacing between nanopillars. However, nanopillar structures are susceptible to external friction, impact, and force, making it challenging to maintain their antibacterial properties. Therefore, in this study, we investigate the antibacterial behavior of nanohole structures, which offer relatively superior mechanical robustness compared to nanopillars. Moreover, for applications in medical devices such as laparoscopes, there is a pressing need for surfaces that are not only transparent and flexible (or curved) but are also equipped with antibacterial properties. Our study introduces a scalable multi-functional surface that synergistically combines antibacterial and anti-fog properties. This is achieved by fabricating thin films with variously sized holes (ranging from 0.3 µm to 4 µm) using polyurethane acrylate (PUA). We assessed the activity of S. aureus on these surfaces and found that a 1 µm-diameter-hole pattern significantly reduced the presence of live S. aureus, without any detection of dead S. aureus. This bacteriostatic effect is attributed to the restricted proliferation due to the confined area provided by the hole pattern. However, the persistence of some live S. aureus on the surface necessitates further measures to minimize bacterial adhesion and enhance antibacterial effectiveness. To address this challenge, we coated the zwitterionic polymer 2-methacryloyloxyethyl phosphorylcholine (MPC) onto the nanohole pattern surface to reduce S. aureus adhesion. Moreover, in long-term experiments on surfaces, the MPC-coated effectively inhibited the colonization of S. aureus (18 h; 82%, 7 days; 83%, and 14 days; 68% antibacterial rate). By integrating PUA, MPC, and nanohole architectures into a single, flexible platform, we achieved a multi-functional surface catering to transparency, anti-fogging, and anti-biofouling requirements. This innovative approach marks a significant advancement in surface engineering, offering a versatile solution applicable in various fields, particularly in preventing S. aureus contamination in invasive medical devices like laparoscopes. The resultant surface, characterized by its transparency, flexibility, and antibacterial functionality, stands out as a promising candidate for mitigating S. aureus-related risks in medical applications. [ABSTRACT FROM AUTHOR]