Antibacterial Nanopillar Array for an Implantable Intraocular Lens

Flexible and transparent nanohole-patterned films with antibacterial properties against Staphylococcus aureus

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.

Biopolymeric Innovations in Ophthalmic Surgery: Enhancing Devices and Drug Delivery Systems

The interface between material science and ophthalmic medicine is witnessing significant advances with the introduction of biopolymers in medical device fabrication. This review discusses the impact of biopolymers on the development of ophthalmic devices, such as intraocular lenses, stents, and various prosthetics. Biopolymers are emerging as superior alternatives due to their biocompatibility, mechanical robustness, and biodegradability, presenting an advance over traditional materials with respect to patient comfort and environmental considerations. We explore the spectrum of biopolymers used in ophthalmic devices and evaluate their physical properties, compatibility with biological tissues, and clinical performances. Specific applications in oculoplastic and orbital surgeries, hydrogel applications in ocular therapeutics, and polymeric drug delivery systems for a range of ophthalmic conditions were reviewed. We also anticipate future directions and identify challenges in the field, advocating for a collaborative approach between material science and ophthalmic practice to foster innovative, patient-focused treatments. This synthesis aims to reinforce the potential of biopolymers to improve ophthalmic device technology and enhance clinical outcomes.

Nanotopology-Enabled On-Site Pathogen Detection for Managing Atopic Dermatitis

Atopic dermatitis (AD), a prevalent skin condition often complicated by microbial infection, poses a significant challenge in identifying the responsible pathogen for its effective management. However, a reliable, safe tool for pinpointing the source of these infections remains elusive. In this study, a novel on-site pathogen detection that combines chemically functionalized nanotopology with genetic analysis is proposed to capture and analyze pathogens closely associated with severe atopic dermatitis. The chemically functionalized nanotopology features a 3D hierarchical nanopillar array (HNA) with a functional polymer coating, tailored to isolate target pathogens from infected skin. This innovative nanotopology demonstrates superior pathogenic capture efficiency, favorable entrapment patterns, and non-cytotoxicity. An HNA-assembled stick is utilized to directly retrieve bacteria from infected skin samples, followed by extraction-free quantitative loop-mediated isothermal amplification (direct qLAMP) for validation. To mimic human skin conditions, porcine skin is employed to successfully capture Staphylococcus aureus, a common bacterium exacerbating AD cases. The on-site detection method exhibits an impressive detection limit of 103 cells mL-1. The HNA-assembled stick represents a promising tool for on-site detection of bacteria associated with atopic dermatitis. This innovative approach enables to deepen the understanding of AD pathogenesis and open avenues for more effective management strategies for chronic skin conditions.

External Stimuli-Responsive Strategies for Surface Modification of Orthopedic Implants: Killing Bacteria and Enhancing Osteogenesis

Bacterial infection and insufficient osteogenic activity are the main causes of orthopedic implant failure. Conventional surface modification methods are difficult to meet the requirements for long-term implant placement. In order to better regulate the function of implant surfaces, especially to improve both the antibacterial and osteogenic activity, external stimuli-responsive (ESR) strategies have been employed for the surface modification of orthopedic implants. External stimuli act as "smart switches" to regulate the surface interactions with bacteria and cells. The balance between antibacterial and osteogenic capabilities of implant surfaces can be achieved through these specific ESR manifestations, including temperature changes, reactive oxygen species production, controlled release of bioactive molecules, controlled release of functional ions, etc. This Review summarizes the recent progress on different ESR strategies (based on light, ultrasound, electric, and magnetic fields) that can effectively balance antibacterial performance and osteogenic capability of orthopedic implants. Furthermore, the current limitations and challenges of ESR strategies for surface modification of orthopedic implants as well as future development direction are also discussed.

Polyaniline-based 3D network structure promotes entrapment and detection of drug-resistant bacteria

Sensitive and accurate capture, enrichment, and identification of drug-resistant bacteria on human skin are important for early-stage diagnosis and treatment of patients. Herein, we constructed a three-dimensional hierarchically structured polyaniline nanoweb (3D HPN) to capture, enrich, and detect drug-resistant bacteria on-site by rubbing infected skins. These unique hierarchical nanostructures enhance bacteria capture efficiency and help severely deform the surface of the bacteria entrapped on them. Therefore, 3D HPN significantly contributes to the effective and reliable recovery of drug-resistant bacteria from the infected skin and the prevention of potential secondary infection. The recovered bacteria were successfully identified by subsequent real-time polymerase chain reaction (PCR) analysis after the lysis process. The molecular analysis results based on a real-time PCR exhibit excellent sensitivity to detecting target bacteria of concentrations ranging from 102 to 107 CFU/mL without any fluorescent signal interruption. To confirm the field applicability of 3D HPN, it was tested with a drug-resistant model consisting of micropig skin similar to human skin and Klebsiella pneumoniae carbapenemase-producing carbapenem-resistant Enterobacteriaceae (KPC-CRE). The results show that the detection sensitivity of this assay is 102 CFU/mL. Therefore, 3D HPN can be extended to on-site pathogen detection systems, along with rapid molecular diagnostics through a simple method, to recover KPC-CRE from the skin.

The impact of preloaded intraocular lens implantation system (TECNIS iTec®) in routine cataract surgery in China: a time-motion analysis

OBJECTIVE

To evaluate the impact on surgical efficiency and labor time cost of preloaded intraocular lens (IOL) implantation system compared with manual IOL implantation system in age-related cataract surgery in China.

METHODS

This study was an observational, multicenter, prospective time-motion analysis. IOL preparation time, operation time, cleaning time, number and cost of cataract surgeries in eight participating hospitals were collected. The linear mixed model was used to explore factors associated with the difference in operation time between the preloaded IOL implantation system and the manual IOL implantation system. A time-motion model was constructed to convert the operation time cost saved by using preloaded IOL into economic benefits from hospital and social perspective, respectively.

RESULTS

There were 2,591 cases included in the study (preloaded IOL: 1,591 cases; manual IOL: 1,000 cases). The preloaded IOL implantation system was significant time-saving in both preparation time and operation time compared to the manual IOL implantation system (25.48s vs. 47.04s, P < 0.001 and 353.84s vs. 367.46s, P = 0.004, respectively). An average total of 35.18s can be saved by using preloaded IOL per procedure. The results of linear mixed model showed that the type of IOL was the main factor leading to the difference in preparation time between preloaded IOL and manual IOL implantation system. By switching from manual IOL to preloaded IOL, the model projected additional 392 surgeries can be performed each year and an increase in revenue of $565,282 per hospital, a 9% increase from hospital perspective. And the annual productivity loss saved by using preloaded IOL was $3,006 in eight hospitals from perspective of society.

CONCLUSION

Compared with manual IOL implantation system, the preloaded IOL implantation system reduces lens preparation time and operation time, which increases potential surgical volume and revenue, and reduces the loss of work productivity. This study provides real-world evidence to support the advantages of the preloaded IOL implantation system in improving efficiency of ophthalmic surgery in China.

Recent nanotechnology-based strategies for interfering with the life cycle of bacterial biofilms

Biofilm formation plays an important role in the resistance development in bacteria to conventional antibiotics. Different properties of the bacterial strains within biofilms compared with their planktonic states and the protective effect of extracellular polymeric substances contribute to the insusceptibility of bacterial cells to conventional antimicrobials. Although great effort has been devoted to developing novel antibiotics or synthetic antibacterial compounds, their efficiency is overshadowed by the growth of drug resistance. Developments in nanotechnology have brought various feasible strategies to combat biofilms by interfering with the biofilm life cycle. In this review, recent nanotechnology-based strategies for interfering with the biofilm life cycle according to the requirements of different stages are summarized. Additionally, the importance of strategies that modulate the bacterial biofilm microenvironment is also illustrated with specific examples. Lastly, we discussed the remaining challenges and future perspectives on nanotechnology-based strategies for the treatment of bacterial infection.

Finite Element Modelling of a Gram-Negative Bacterial Cell and Nanospike Array for Cell Rupture Mechanism Study

Inspired by nature, it is envisaged that a nanorough surface exhibits bactericidal properties by rupturing bacterial cells. In order to study the interaction mechanism between the cell membrane of a bacteria and a nanospike at the contact point, a finite element model was developed using the ABAQUS software package. The model, which saw a quarter of a gram-negative bacteria (Escherichia coli) cell membrane adhered to a 3 × 6 array of nanospikes, was validated by the published results, which show a reasonably good agreement with the model. The stress and strain development in the cell membrane was modeled and were observed to be spatially linear and temporally nonlinear. From the study, it was observed that the bacterial cell wall was deformed around the location of the nanospike tips as full contact was generated. Around the contact point, the principal stress reached above the critical stress leading to a creep deformation that is expected to cause cell rupture by penetrating the nanospike, and the mechanism is envisaged to be somewhat similar to that of a paper punching machine. The obtained results in this project can provide an insight on how bacterial cells of a specific species are deformed when they adhere to nanospikes, and how it is ruptured using this mechanism.

Surface modification of commercial intraocular lens by zwitterionic and antibiotic-loaded coating for preventing postoperative endophthalmitis

After cataract surgery, to prevent possible postoperative endophthalmitis (POE) caused by attached pathogenic bacteria onto the surface of implanted intraocular lens (IOL), various antibiotic-loaded IOLs have been proposed and widely studied to inhibit bacterial infection. However, most of these developed antibiotic-loaded IOLs still suffer from shortcomings such as insufficient drug loading, short release time, poor biocompatibility, and risk of secondary infection. Herein, we propose a zwitterionic and high-drug loading coating for surface modification of commercial hydrophobic IOL with both antifouling and antibacterial properties to effectively prevent POE. In this strategy, zwitterionic poly(carboxylbetaine-co-dopamine methacrylamide) copolymers (pCBDA) and dopamine (DA) were first robustly co-deposited onto IOL surface via facile mussel-inspired chemistry, resulting in a hydrophilic coating (defined as PCB) without sacrificing the high light transmittance of the native IOL. Subsequently, amikacin (AMK), an amine-rich antibiotic was reversibly conjugated onto the coating through the acid-sensitive Schiff base bonds formed by the reaction between amino and catechol groups, with high-drug payload over ∼35.5 μg per IOL and 30 days of sustained drug release under weak acid environment. Benefiting from the antifouling property of zwitterionic pCBDA copolymers, the intraocularly implanted PCB/AMK-coated IOL could effectively resist the adhesion and proliferation of residual LECs to inhibit the development of posterior capsule opacification (PCO) without affecting the normal ocular tissues, demonstrating excellent in vivo biocompatibility. Moreover, the synergy of zwitterionic pCBDA and conjugated AMK with acidic-dependent release behavior endowed this PCB/AMK-coated IOL strong antibacterial activity against both in vitro biofilm formation and in vivo postoperative Staphylococcus aureus infection, suggesting its promising application in preventing POE.

Combining Topography and Chemistry to Produce Antibiofouling Surfaces: A Review

Despite decades of research on the reduction of surface fouling from biomolecules or micro-organisms, the ultimate antibiofouling surface remains undiscovered. The recent covid-19 pandemic strengthened the crucial need for such treatments. Among the numerous approaches that are able to provide surfaces with antibiofouling properties, chemical, biological, and topographical strategies have been implemented for instance in the marine, medical, or food industries. However, many of these methods have a biocidal effect and, with antibioresistance and biocide resistance a growing threat on humanity, strategies based on reducing adsorption of biomolecules and micro-organism are necessary for long-term solutions. Bioinspired strategies, combining both surface chemistry and topography, are currently at the heart of the best innovative and sustainable solutions. The synergistic effect of micro/nanostructuration, together with engineered chemical or biological functionalization is believed to contribute to the development of antibiofouling surfaces. This review aims to present approaches combining hydrophobic or hydrophilic chemistries with a specific topography to avoid biofouling in various industrial environments and healthcare facilities.

Recent Advances of Intraocular Lens Materials and Surface Modification in Cataract Surgery

Advances in cataract surgery have increased the demand for intraocular lens (IOL) materials. At present, the progress of IOL materials mainly contains further improving biocompatibility, providing better visual quality and adjustable ability, reducing surgical incision, as well as dealing with complications such as posterior capsular opacification (PCO) and ophthalmitis. The purpose of this review is to describe the research progress of relevant IOL materials classified according to different clinical purposes. The innovation of IOL materials is often based on the common IOL materials on the market, such as silicon and acrylate. Special properties and functions are obtained by adding extra polymers or surface modification. Most of these studies have not yet been commercialized, which requires a large number of clinical trials. But they provide valuable thoughts for the optimization of the IOL function.

3D Hierarchical Polyaniline-Metal Hybrid Nanopillars: Morphological Control and Its Antibacterial Application

Effective and reliable antibacterial surfaces are in high demand in modern society. Although recent works have shown excellent antibacterial performance by combining unique hierarchical nanotopological structures with functional polymer coating, determining the antibacterial performance arising from morphological changes is necessary. In this work, three-dimensional (3D) hierarchical polyaniline–gold (PANI/Au) hybrid nanopillars were successfully fabricated via chemical polymerization (i.e., dilute method). The morphology and structures of the PANI/Au nanopillars were controlled by the reaction time (10 min to 60 h) and the molar concentrations of the monomer (0.01, 0.1, and 1 M aniline), oxidant (0.002, 0.0067, 0.01, and 0.02 M ammonium persulfate), and acid (0.01, 0.1, 1, and 2 M perchloric acid). These complex combinations allow controlling the hierarchical micro- to nanostructure of PANI on a nanopillar array (NPA). Furthermore, the surface of the 3D PANI/Au hierarchical nanostructure can be chemically treated while maintaining the structure using initiated chemical vapor deposition. Moreover, the excellent antibacterial performance of the 3D PANI/Au hierarchical nanostructure (HNS) exceeds 99% after functional polymer coating. The excellent antibacterial performance of the obtained 3D PANI/Au HNS is mainly because of the complex topological and physicochemical surface modification. Thus, these 3D PANI/Au hierarchical nanostructures are promising high-performance antibacterial materials.

All-in-One DNA Extraction Tube for Facilitated Real-Time Detection of Infectious Pathogens

An "all-in-one tube" platform is developed, where the genetic analysis involving DNA extraction, amplification, and detection can be performed in a single tube. The all-in-one tube consists of a polymerase chain reaction (PCR) tube in which the inner surface is conformally modified with a tertiary-amine-containing polymer to generate a strong electrostatic interaction with DNA. The all-in-one tube provides high DNA capture efficiency exceeding 80% from Escherichia coli O157: H7 pathogen at a wide range of DNA amount from 0.003 to 3 ng. Indeed, the use of the surface-functionalized PCR tube enables direct amplification and detection of the surface-captured DNA without the modification of standard real-time PCR instrument. Besides, this platform has sensitivity, selectivity, and reliability enough for accurate detection at the minimal infective dose of both gram-positive and negative pathogens. The all-in-one tube enables the direct molecular diagnosis, substantially reducing the labor-intensive pathogen detection steps while providing high compatibility with the currently established real-time PCR instruments, and illustrates its on-site applicability with convenience expandable to various genetic analyses including food safety testing, forensic analysis, and clinical diagnosis.

Wearable and Implantable Soft Bioelectronics: Device Designs and Material Strategies

High-performance wearable and implantable devices capable of recording physiological signals and delivering appropriate therapeutics in real time are playing a pivotal role in revolutionizing personalized healthcare. However, the mechanical and biochemical mismatches between rigid, inorganic devices and soft, organic human tissues cause significant trouble, including skin irritation, tissue damage, compromised signal-to-noise ratios, and limited service time. As a result, profuse research efforts have been devoted to overcoming these issues by using flexible and stretchable device designs and soft materials. Here, we summarize recent representative research and technological advances for soft bioelectronics, including conformable and stretchable device designs, various types of soft electronic materials, and surface coating and treatment methods. We also highlight applications of these strategies to emerging soft wearable and implantable devices. We conclude with some current limitations and offer future prospects of this booming field.

A Versatile Surface Modification Method via Vapor-phase Deposited Functional Polymer Films for Biomedical Device Applications

For last two decades, the demand for precisely engineered three-dimensional structures has increased continuously for the developments of biomaterials. With the recent advances in micro- and nano-fabrication techniques, various devices with complex surface geometries have been devised and produced in the pharmaceutical and medical fields for various biomedical applications including drug delivery and biosensors. These advanced biomaterials have been designed to mimic the natural environments of tissues more closely and to enhance the performance for their corresponding biomedical applications. One of the important aspects in the rational design of biomaterials is how to configure the surface of the biomedical devices for better control of the chemical and physical properties of the bioactive surfaces without compromising their bulk characteristics. In this viewpoint, it of critical importance to secure a versatile method to modify the surface of various biomedical devices. Recently, a vapor phase method, termed initiated chemical vapor deposition (iCVD) has emerged as damage-free method highly beneficial for the conformal deposition of various functional polymer films onto many kinds of micro- and nano-structured surfaces without restrictions on the substrate material or geometry, which is not trivial to achieve by conventional solution-based surface functionalization methods. With proper structural design, the functional polymer thin film via iCVD can impart required functionality to the biomaterial surfaces while maintaining the fine structure thereon. We believe the iCVD technique can be not only a valuable approach towards fundamental cell-material studies, but also of great importance as a platform technology to extend to other prospective biomaterial designs and material interface modifications for biomedical applications.

Multifunctional Printable Micropattern Array for Digital Nucleic Acid Assay for Microbial Pathogen Detection

The digital nucleic acid assay is a precise, sensitive, and reproducible method for determining the presence of individual target molecules separated in designated partitions; thus, this technique can be used for the nucleic acid detection. Here, we propose a multifunctional micropattern array capable of isolating individual target molecules into partitions and simultaneous on-site cell lysis to achieve a direct DNA extraction and digitized quantification thereof. The multifunctional micropattern array is fabricated by the deposition of a copolymer film, poly(2-dimethylaminomethyl styrene-co-hydroxyethyl methacrylate) (pDH), directly on a microfluidic chip surface via the photoinitiated chemical vapor deposition process, followed by hydrophobic microcontact printing (μCP) to define each partition for the nucleic acid isolation. The pDH layer is a positively charged surface, which is desirable for the bacterial lysis and DNA capture, while showing exceptional water stability for more than 24 h. The hydrophobic μCP-treated pDH surface is stable under aqueous conditions at a high temperature (70 °C) for 1 h and enables the rapid and reliable formation of thousands of sessile microdroplets for the compartmentalization of an aqueous sample solution without involving bulky and costly microfluidic devices. By assembling the multifunctional micropattern array into the microfluidic chip, the isothermal amplification in each partition can detect DNA templates over a concentration range of 0.01-2 ng/μL. The untreated bacterial cells can also be directly compartmentalized via the microdroplet formation, followed by the on-site cell lysis and DNA capture on the compartmentalized pDH surface. For Escherichia coli O157:H7, Salmonella enteritidis, and Staphylococcus aureus cells, cell numbers ranging from 1.4 × 10⁴ to 1.4 × 10⁷ can be distinguished by using the multifunctional micropattern array, regardless of the cell type. The multifunctional micropattern array developed in this study provides a novel multifunctional compartmentalization method for rapid, simple, and accurate digital nucleic acid assays.

A Critical Appraisal of New Developments in Intraocular Lens Modifications and Drug Delivery Systems for the Prevention of Cataract Surgery Complications

Cataract surgery is the commonest ophthalmic surgery worldwide. The replacement of the diseased lens with a synthetic one (intraocular lens-IOL) remains the treatment of choice, despite its potential complications that include infection, inflammation and posterior capsule opacification. The potential for drug delivery via the IOL has been researched extensively over a period of twenty-five years, yet there is very limited progress in transferring the findings from research to everyday practice. The objective of this review is to assess the progress made in the field of IOL lens modifications and drug delivery systems over the past five years. Thirty-six studies that were conducted during the past five years were identified and deemed suitable for inclusion. They were grouped in three broad categories, studies that described new methods for loading a drug onto the IOL, assessment of the effects of drugs that were loaded to the IOL and studies that assessed the effects of non-pharmaceutical modifications of IOLs. While considerable progress is continually being made with regard to methods and materials, there is still little capitalization upon these research studies, with no commercially available IOL-based drug delivery system being available. Close cooperation between researchers in basic sciences (chemistry, physics, materials science and pharmacy), clinical researchers, IOL manufacturers and the pharmaceutical industry is an important prerequisite for further development.