Spiked Nanostructures Disrupt Fungal Biofilm and Impart Increased Sensitivity to Antifungal Treatment

Abstract

The superiority of titanium as a biomaterial is reflected in its corrosion resistance, mechanical strength, biocompatibility, and osseointegration capabilities. [1a] Although there is a high success rate associated with implanted devices, failure is not uncommon. One of the primary causes of implant failure is implantassociated infections (IAI). [2] In the field of orthopaedics, approximately 1-2% of joint replacement arthroplasties result in IAI. [3] The IAI rate is significantly higher in the periodontal field, with peri-implantitis seen in as many as 1 in 3 patients. [4] Infections involving fungal pathogens are emerging in both of these clinical fields, and Candida species are detected in as many as 90% of fungal IAI cases. [5] Candida albicans represents the most common fungal threat, but other notable species include Candida parapsilosis, Candida tropicalis, and Candida glabrata. [5d] In polymicrobial biofilms, C. albicans can protect Porphyromonas gingivalis from adverse conditions [6] and promote drug resistance in Staphylococcus aureus. [7] Its common occurrence in IAI can be attributed to the fact that C. albicans is found amongst the normal skin microbiota as a commensal microbe, and can occasionally translocate from the skin to the implanted device during surgery. [8] In a subset of the population, such as diabetics or those who have an otherwise compromised immune system, C. albicans can switch from its normal commensal state to an opportunistic pathogen. This is of particular concern because once a fungal infection becomes systemic, it is associated with a mortality rate of up to 50%. [9] In systemic candidiasis, the kidney is one of the primary organs to be affected, commonly leading to renal failure. [10] As a fungal pathogen, the virulence mechanisms of C. albicans differ from bacterial pathogens. One striking difference is the ability of pathogenic fungi to reversibly switch between two alternate phenotypes-an ovoid-shaped yeast phenotype and a filamentous hyphal phenotype, and this process is referred to as morphogenesis. [11] The yeast phenotype is associated with initial surface colonization, and later dissemination. The hyphal phenotype acts as structural support and promotes tissue invasion. [12] Invasion of host tissue allows C. albicans to enter the bloodstream and translocate around the body. Within the bloodstream, the presence of serum and the slightly alkaline pH provides ideal conditions for hyphal cell growth, which then allows the pathogen to invade There is a globally increasing demand for medically implanted devices, partly spurred by an aging population. In parallel, there is a proportionate increase in implant associated infection. Much focus has been directed toward the development of techniques to fabricate nanostructured antimicrobial biomaterials to mitigate infection. The present study investigates the interaction of the fungal pathogen Candida albicans with an antimicrobial surface bearing nanoscale protrusions. C. albicans cells were observed to be affected by cell ...

Antibacterial Nanostructured Surfaces Modulate Protein Adsorption, Inflammatory Responses, and Fibrous Capsule Formation

“…It is evident from the SEM images that on the HT surfaces, bacteria had flattened and disrupted the EPS matrix and damaged the cellular membranes. This observation is consistent with a contact killing mechanism proposed by others and our studies. − …”

Biomimetic Nanopillar Silicon Surfaces Rupture Fungal Spores

“…In case of filamentous fungi, initiation of the biofilm starts with the germination of spores attached to a substrate surface. Recently the antifungal capabilities of nanostructured surfaces toward Candida albicans and other yeasts were shown to result from a purported physical mechanism, sometimes in addition to the toxic activity of generated strong reactive oxygen species (ROS) [ 49 , 50 , 51 , 52 , 53 ]. For example, Xie et al reported that C. albicans cells were mechanically ruptured when interacting with ZnO nanostructured substrates (a polygonal column structure with a height of 3–5 μm and a width of 100–200 nm) [ 54 ].…”

Early Antimicrobial Evaluation of Nanostructured Surfaces Based on Bacterial Biological Properties

“…2,3 It is widely accepted that the antibacterial effects of the early adhesion stage are better than those of the mature biofilm formation because the mature biofilm on biomaterials can hardly be thoroughly eradicated. 1,4 Consequently, diverse strategies have been developed to cope with the early bacterial adhesion, such as developing specific topologies 5 and preparing bactericidal coatings or local drug delivery systems. 6,7 Considering the increasing antibiotic resistance of bacteria, physical antibacterial surfaces, especially the ones with nanoscaled structures, have drawn extensive attention during the past decade.…”

“…Bacteria-related infection (BRI) has become a major challenge in the field of biomaterial implantation . Severe BRI is a destructive complication that leads to local infection, systemic infection, organ dysfunction, and even death. , It is widely accepted that the antibacterial effects of the early adhesion stage are better than those of the mature biofilm formation because the mature biofilm on biomaterials can hardly be thoroughly eradicated. , Consequently, diverse strategies have been developed to cope with the early bacterial adhesion, such as developing specific topologies and preparing bactericidal coatings or local drug delivery systems. , Considering the increasing antibiotic resistance of bacteria, physical antibacterial surfaces, especially the ones with nanoscaled structures, have drawn extensive attention during the past decade . However, many studies, focusing on the physical antimicrobial behavior of biomaterials, usually show contradictory results, even on the substrates with the same surface treatment. , For example, the physiologically young bacteria adhere in large numbers on the nanostructured surfaces, while the attachment of physiologically old bacteria on the nanostructured surfaces is inhibited .…”