Surface coating with pharmacological molecules

INTRODUCTION

In the continuously changing realm of surgical practice, the quest for novel techniques and technologies is essential for enhancing patient outcomes and progressing the discipline.^[1] The application of pharmacological molecules as surface coatings signifies a promising advancement in surgical innovation, with the potential to improve the safety, effectiveness and adaptability of surgical techniques.^[2] This method seeks to tackle persistent issues such as infection, integration of implants and tissue regeneration by coating surgical implants and devices with a thin layer of bioactive materials.^[3]

The application of pharmacological molecules as surface coatings presents an innovative strategy to tackle these issues, utilising the therapeutic benefits of drugs and biologics to enhance patient outcomes.^[4] Historically, surgical procedures have faced challenges due to complications including implant rejection, bacterial infections and inadequate healing.^[5] The incorporation of pharmacologically active substances into surface coatings offers an innovative approach to address these challenges. By utilising the therapeutic effects of drugs and biologics, surfaces that are pharmacologically coated can influence biological reactions at the interface between the implant and surrounding tissue, thereby enhancing beneficial results and reducing negative effects.^[6]

This review establishes a foundation for an in-depth examination of the use of pharmacological molecules in surface coatings within the field of surgery. We will investigate the development, applications, advantages, challenges and future potential of this cutting-edge technique. By fostering interdisciplinary collaboration and advancing scientific knowledge, the application of pharmacological surface coatings has the potential to revolutionise surgical practices, paving the way for a new era of precision medicine and enhanced patient outcomes.

PRINCIPLES OF SURFACE COATING

Surface coating, often referred to as surface finishing, entails the application of a protective or aesthetic layer onto the surface of a substrate. The fundamental principles of surface coating encompass several elements, such as the choice of coating materials, techniques for application, curing procedures and measures for quality assurance.^[7] Here are some fundamental principles:

• Substrate Preparation: The effective preparation of the substrate is essential for ensuring strong adhesion and long-lasting durability of the coating. This process may include steps such as cleaning, degreasing, sanding and, in some cases, the application of a primer or conversion coating to improve adhesion.^[8,9]

• Selection of Coating Material: Selecting the appropriate coating material is influenced by several factors, including the type of substrate, environmental conditions and the specific aesthetic and performance criteria needed, such as resistance to corrosion, chemicals and ultraviolet (UV) light.^[10]

• Application Method: Different techniques exist for the application of coatings, such as spraying, brushing, dipping, rolling, electroplating and powder coating. The selection of a particular method is influenced by several factors, including the nature of the coating, the geometry of the substrate, the volume of production and the quality of finish required.^[11,12]

• Curing or Drying: Following application, the coating is required to undergo a curing or drying phase to establish a solid, adherent layer. Curing techniques may encompass air drying, heat curing (such as microwave curing)^[13] and chemical curing (e.g. crosslinking)^[14] or UV curing.^[15]

• Quality Control: Quality control measures are crucial for verifying that coated products fulfil established criteria. This process involves examining substrate characteristics, including integrity, uniformity, surface roughness, thickness and hydrophilicity.^[16]

• Environmental and Safety Considerations: Surface coating procedures frequently utilise chemicals, which can lead to the production of hazardous waste or emissions. Consequently, it is essential to establish appropriate safety protocols and environmental regulations to reduce health risks for workers and mitigate environmental effects.^[17]

APPLICATIONS IN SURGERY

In the field of surgery, surface coating involves the application of various coatings or surface treatments to medical devices, implants or surgical instruments with the aim of improving their performance, biocompatibility and safety. The underlying principles of surface coating in this context are centred on enhancing the functionality and biocompatibility of these devices, ultimately leading to improved outcomes for patients.^[2,18,19] Initially, it is essential for surface coatings to possess biocompatibility, which indicates that they do not provoke detrimental responses on interaction with biological tissues. Coatings that are biocompatible contribute to the reduction of tissue irritation, inflammation and the likelihood of negative reactions, thereby enhancing the safety of medical devices intended for use within the human body.^[20] Coatings can be utilised on surgical instruments or implants to minimise friction and wear throughout surgical operations. The application of low-friction coatings enhances the manoeuvrability of instruments and decreases tissue damage, resulting in improved surgical results and expedited recovery for patients.^[21,22] In addition, certain surface coatings include antimicrobial substances designed to inhibit bacterial growth and diminish the likelihood of surgical site infections. Such coatings contribute to preserving a sterile surgical environment and decreasing the occurrence of postoperative complications.^[23,24] In addition, coatings that possess lubricating characteristics can be utilised on surgical instruments or devices to promote seamless movement and decrease friction throughout procedures. Improved lubrication can enhance the effectiveness of surgical operations and lessen the risk of tissue injury.^[25] Surface coatings can exhibit anti-adhesive characteristics that inhibit the attachment of biological substances, including blood, tissue and other bodily fluids. These anti-adhesive properties are beneficial in surgical settings, as they enhance visibility and simplify the cleaning and sterilisation processes of surgical instruments.^[26,27] Coatings play a crucial role in safeguarding surgical instruments and implants against corrosion, which may arise from contact with bodily fluids or aggressive chemical conditions within the body. By utilising corrosion-resistant coatings, the durability of medical devices is enhanced, thereby ensuring their effective performance over an extended period.^[28,29] Surface coatings can be customised to alter particular surface characteristics of medical devices, including hydrophobicity.^[30] Finally, the surface coatings used on medical devices are required to adhere to regulatory standards and requirements to guarantee their safety and effectiveness. Regulatory organisations, including the U.S. Food and Drug Administration and the European Medicines Agency, establish guidelines for the assessment and authorisation of coatings for medical devices.^[31] A summary is shown in Table 1.

PHARMACOLOGICALLY COATED SURFACES

Pharmacologically coated surfaces provide numerous advantages across a range of medical applications, especially within the domains of interventional orthopaedics, dentistry and cardiology.^[32,33] Pharmacologically coated surfaces have the capability to locally deliver antiplatelet or anticoagulant drugs, thereby aiding in the prevention of thrombosis, or blood clot formation, on medical devices such as stents and catheters. This function is especially vital in interventions such as coronary angioplasty and stent insertion, as thrombosis can result in severe complications, including heart attacks or strokes.^[34,35] Restenosis, characterised by the re-narrowing of the artery, may arise in coronary stents as a result of excessive tissue proliferation at the stent implantation site. The application of pharmacological agents to the surfaces of medical devices can improve their biocompatibility, thereby minimising the likelihood of negative reactions or inflammatory responses. This consideration is especially crucial for long-term implants, such as vascular stents and orthopaedic devices.^[35] Pharmacologically coated surfaces facilitate the precise and localised administration of drugs to designated target areas within the body. This method of targeted drug delivery reduces systemic side effects while enhancing therapeutic effectiveness by directing medications straight to the intended site of action.^[36-38] Applying pharmacological agents that stimulate bone growth or reduce inflammation to orthopaedic implants can facilitate the healing process and enhance the integration of the implant with adjacent tissues. This approach may result in quicker recovery periods and better long-term results for patients undergoing joint replacement procedures.^[39] Certain surfaces treated with pharmacological coatings include antimicrobial substances that aid in inhibiting bacterial growth and minimising the likelihood of infections related to implants. This is especially crucial for devices like urinary catheters, as infections can result in significant complications.^[40] Pharmacologically coated surfaces can extend the longevity of medical devices and minimise the necessity for additional procedures or device replacements by mitigating complications such as thrombosis, restenosis and infection.^[41] Pharmacologically coated surfaces enable the personalisation of treatment according to the unique requirements of each patient. Various medications or drug combinations can be integrated into these coatings to target diverse medical conditions or specific patient attributes.^[42] Pharmacologically coated surfaces present considerable opportunities to enhance the safety, effectiveness and durability of medical devices and implants, ultimately resulting in improved clinical results and superior patient care. A summary is shown in Table 1.

ANTICORROSION COATINGS

Metallic materials find a wide range of applications in the fields of medicine and dentistry, including dental implants, orthopaedic fixations, orthodontic devices, joint replacements, stents, as well as endodontic files and reamers.^[43] The drawback associated with these biomaterials is the release of metal ions, including nickel, titanium and silver (Ag). Consequently, the application of coatings on metallic materials is crucial in addressing these issues.^[43,44] Although numerous coatings are currently being explored for application on metallic biomaterials, particularly nitinol, achieving a successful coating remains a persistent challenge.^[45-58] Significant drawbacks associated with polymer coatings encompass the toxicity linked to the roughness of the components, their porosity and the potential for the coatings to detach.^[59] Graphene, despite being only one atom in thickness, exhibits inert properties and demonstrates resistance to both water and oxygen. The combination of these properties, along with their durability and atomic stability, has demonstrated that graphene is effective as a corrosion barrier film.^[60-63] Magnesium (Mg) has the potential to be utilised in the production of biodegradable implants; nevertheless, its primary limitation lies in the challenges associated with managing its corrosion rate effectively. Catt et al.^[61] introduced a conductive polymer, poly(3,4-ethylene dioxythiophene) (PEDOT), in conjunction with a graphene oxide (GO) coating for Mg implants, with the objective of reducing corrosion. Their research revealed a significant decrease in the concentration of Mg ions and a lowering of the pH in the surrounding environment, suggesting improved corrosion resistance. In addition, a decrease in hydrogen gas evolution was noted. The efficacy of the coating can be attributed to three primary factors: The development of a passive layer that restricts solution infiltration, the presence of negative charges on the film and the formation of a corrosion-resistant Mg-phosphate layer. Moreover, the coating exhibited promising biocompatibility in vitro, showing no toxic effects on cultured neuronal cells. As a result, the PEDOT/GO coating is demonstrated to be effective in preventing corrosion in Mg-based implants. Zhou et al.^[63] investigated the bioactive characteristics of titanium substrates coated with GO in relation to periodontal ligament stem cells (PDLSCs), comparing these results with those obtained from sodium titanate substrates. The results revealed that PDLSCs grown on GO-coated titanium substrates exhibited a marked increase in alkaline phosphatase (ALP) activity, higher proliferation rates and elevated expression levels of osteogenic genes, including ALP, runt-related transcription factor 2 (Runx2), bone sialoprotein and osteocalcin (OCN), in comparison to those cultured on sodium titanate substrates. In addition, the presence of GO significantly enhanced the protein expressions of Runx2, bone sialoprotein and OCN. Graphene can be directly synthesised on various metallic substrates, including Mg, zinc, nickel and aluminium, leading to the creation of a protective layer.^[60,62,64] Singh et al.^[65] effectively created a graphene composite coating designed to inhibit corrosion on copper (Cu) substrates. In the field of dentistry, graphene coatings have the potential to protect a range of metallic biomaterials, including archwires, files, reamers and various types of metallic prostheses, from corrosion. Hikku et al.^[66] investigated the anti-corrosion characteristics of a graphene and polyvinyl nanocomposite coating applied to aluminium-2219 alloy. Graphene coatings have the potential to enhance the surface characteristics of implants while simultaneously mitigating corrosion.^[67,68] Suo et al.^[67] successfully created a uniform coating composed of GO/chitosan/hydroxyapatite (GO/CS/HA) on titanium substrates using electrophoretic deposition. This innovative GO/CS/HA coating demonstrated enhanced wettability and bonding strength when compared to coatings made solely of HA, GO/HA and CS/HA. In addition, the GO/CS/HA coating significantly enhanced cell-material interactions in vitro and promoted osseointegration in vivo. As a result, the utilisation of GO/CS/HA coatings on titanium emerges as a promising strategy for applications in implant dentistry. The GO coating holds considerable potential in tissue engineering and regenerative medicine, particularly in areas such as managing root fractures, cementing prosthetic devices, pulp therapy and addressing bone defects through filling, repair and regeneration. These applications may greatly benefit from the use of bioactive cement, which is known for its capacity to release calcium ions (Ca²⁺), increase the alkalinity of the surrounding environment and encourage cell differentiation and the development of mineralised tissue. However, it is crucial to acknowledge that bioactive cement often suffers from insufficient mechanical properties, rendering it vulnerable to fractures due to its limited strength and fracture toughness.^[69] The incorporation of graphene enhances the mechanical properties significantly. An increase in the strength of 58S bioactive glass was noted, with a doubling effect achieved through the addition of 0.5 wt.%.^[70] The incorporation of GO^[70] and reduced GO (rGO)^[71] has demonstrated notable enhancements in mechanical properties. Specifically, the introduction of rGO at a concentration of 1 wt.% led to a remarkable 200% enhancement in the fracture toughness of HA.^[70] The addition of graphene markedly improves the bioactive properties of bone cement. Studies have shown that different cell types, including bone marrow stem cells, PDLSCs and dental pulp stem cells, demonstrate spontaneous osteogenic differentiation when in contact with pristine graphene scaffolds and substrates created through chemical vapour deposition.^[72,73] In vivo bone formation was demonstrated through the implantation of GO-coated collagen scaffolds into the tooth extraction sockets of beagle dogs. After a period of 14 days, the GO-coated scaffolds exhibited enhanced bone formation and calcium absorption, in contrast to the control scaffolds, which were predominantly occupied by connective tissue.^[74] A summary is shown in Table 1.

ANTIBACTERIAL COATINGS

Contact-active antimicrobial coatings (AMCs) are designed to eliminate pathogens through direct contact, without the need for antimicrobial substances to leach from the surface. These coatings can be applied in extremely thin layers, even at the molecular level, which reduces the amount of antimicrobial agents needed, thereby enhancing their potential for environmental sustainability. It is crucial that the active antimicrobial agents are securely bound to the surface and contain functional antimicrobial groups. The biocidal action of these coatings is dependent on their interaction with pathogens and does not involve the release of active agents, allowing for prolonged antimicrobial effectiveness unless the surface is compromised by factors such as the accumulation of dead cells or other contaminants. In general, contact-active coatings are derived from antimicrobial polymers, which can be categorised as either natural – obtained directly from natural sources or synthesised to imitate natural substances – or synthetic, created from chemical monomers. These antimicrobial polymers are affixed to surfaces to create contact-active coatings that retain their antimicrobial efficacy.^[75]

Coatings that utilise CS, a biocompatible polysaccharide made up of N-acetylglucosamine and D-glucosamine, offer a promising avenue for contact-active AMCs. This natural cationic polymer demonstrates antimicrobial efficacy attributed to the positively charged amine groups within its molecular structure. As a sustainable biocide, the antimicrobial effectiveness of CS can be fine-tuned by modifying the amine functionalities and incorporating them into suitable polymer matrices.^[75] During the biocidal action, the surface of a polycationic biocide may become covered with dead cells, resulting in a loss of antimicrobial activity. However, the activity of these surfaces can be restored through washing with cationic detergents, which help remove the accumulated cellular debris.^[75] An alternative class of antimicrobial substances that can be anchored to surfaces through polymeric brushes is antimicrobial peptides (AMPs).^[76] AMPs, such as magainin and defensin, or their synthetic mimics, can be integrated into contact-active AMCs.^[76-78] The antimicrobial mechanism of AMPs is primarily attributed to two key properties: a highly rigid backbone and the strategic arrangement of one hydrophobic and one cationic side group. These structural features enable the AMP to effectively penetrate and disrupt the cell membrane.^[76-78]

A typical contact-active AMC, such as a quaternary ammonium compound (QAC), forms electrostatic interactions with negatively charged components of the cell membrane, disrupting the integrity and function of the entire cell. At lethal concentrations, QACs can displace cytoplasmic components and dissociate phospholipids.^[79] Direct incorporation of QAC into coatings often results in high levels of leaching, rapid depletion of the biocide and increased environmental toxicity. A more widely accepted approach involves grafting the active QAC onto a polymer, which facilitates binding and anchoring of the QAC to various surfaces.^[80] The biocide 3-(trimethoxysilyl)-propyldimethyloctadecyl ammonium chloride, an organosilicon QAC (Si-QAC)^[80,81] is anchored to surfaces through the silane group of the Si-QAC, which condenses with free hydroxyl groups on the surface. This anchorage is further stabilised by intermolecular siloxane (Si-O-Si) linkages.^[82,83] The antimicrobial action of Si-QAC is primarily attributed to the quaternary amine (N+) group, which attracts negatively charged microbial cells. These cells are then drawn to the needle-like C18 structure of the hydrophobic chain, leading to puncture of the bacterial cell envelope and subsequent events that result in cell death.

Polyaniline (PANI) has been identified as a promising material for contact-active AMCs.^[84,85] The surface of PANI is conductive, attracting negatively charged bacteria through electrostatic interactions.^[86] However, the antimicrobial activity of PANI can be influenced by changes in its structural chemistry with pH; specifically, the emeraldine salt form exhibits greater activity than the emeraldine base form, which may pose challenges to maintaining sustained antimicrobial efficacy.^[87,88] The commercialisation of contact-active AMCs is fraught with greater difficulties than that of biocide-releasing AMCs, primarily due to the elevated production costs and longer timeframes involved. Although contact-active AMCs are generally considered to be less harmful to the environment than their biocide-releasing counterparts, the active components within them can still become depleted over time. On the other hand, biocide-releasing AMCs, which follow a more traditional design approach, provide a variety of broad-spectrum agents for controlled release. Nevertheless, they encounter multiple challenges, such as interference from residual dead cells, depletion of the biocide reservoir that restricts the active lifespan of the surface and the risk of developing resistance at sub-minimum inhibitory concentration levels. Furthermore, the release of biocides may introduce potential hazards related to human and environmental toxicity.^[89] Biocide-releasing AMCs can be categorised based on the biocide release mechanism. The simplest form involves continuous release, where a biocide gradient creates an outer inhibition zone and an inner kill zone to protect the surface from pathogen colonisation. While such surfaces can prevent microbial attachment, they deplete quickly and require frequent replacement. Common biocides for these AMCs include metals, metal oxides and nanoparticles of Ag and Cu. Ag, widely recognised for its biocidal activity, works by accumulating positively charged ions at the negatively charged regions of the microbial cell membrane, causing membrane damage and cell death. Ag-based AMCs may incorporate Ag alloys, nanoparticles, Ag oxide, chelated Ag, metallic Ag or Ag salts. Among these, Ag nanoparticles have shown superior efficacy, as they not only release Ag ions but also generate reactive oxygen species, directly damaging the cell membrane. Cu, a cost-effective alternative to Ag, also exhibits strong biocidal properties, including effective DNA degradation that limits the transmission of antibiotic and biocide resistance genes.^[90] While both Ag and Cu coatings show high antibacterial and antiviral activity^[90] their application has been primarily tested on small objects, such as doorknobs and bed rails, with limited testing on large surfaces like walls. Moreover, the real-world effectiveness of these coatings in reducing healthcare-associated infections (HAIs) remains under investigation, although some studies show promising results for Cu coatings. One major limitation of Ag coatings is their reduced efficacy under low temperature and humidity conditions, which often reflect real-world settings. To address the rapid depletion of biocides in continuous release AMCs, slow-release mechanisms have been explored. By incorporating biocides into a polymer matrix, the release rate can be controlled. Techniques such as drug delivery systems can be employed, using biocide carriers such as polylactic acid, polyesters or polyelectrolyte multilayers to enable slow release. In antibiotic-based AMCs, HA is often used as a biocompatible carrier, with modified forms such as carbonated hydroxyapatite offering improved incorporation and slower release of antibiotics. Some AMCs, such as those incorporating Ag without continuous release, fall under slow-release mechanisms. For example, glass slides coated with nanosilver (1–2 nm) and modified with poly(ethyleneimine) exhibit significant antimicrobial activity against Escherichia coli without releasing substantial amounts of Ag into the environment. Slow-release coatings are expected to maintain antimicrobial efficacy for longer periods compared to continuous-release coatings, although their higher cost may limit their use on large objects. Continuous leaching of biocide from AMCs raises concerns about their efficiency and durability. Ideally, surfaces should be capable of detecting microbial presence and releasing biocides only when necessary. Triggered-release biocidal coatings address this issue by responding to specific external stimuli, such as bacterial molecules or host infection signals. For instance, quorum-sensing molecules, such as homoserine lactones in Gram-negative bacteria, can trigger biocide release when their concentration exceeds a threshold value. An example includes the release of ciprofloxacin in response to quorum-sensing lipase-sensitive homoserine groups on a polyethylene glycol-like polymer. Another example involves a thrombin-degradable peptide linker cross-linked with polyvinyl alcohol, which releases encapsulated antibiotics in response to an increase in thrombin during infection. While triggered-release AMCs offer a more sophisticated approach than continuous or slow-release coatings, their complexity may limit their applicability to specialised surfaces. The requirement for specific stimuli to activate the coating raises questions about the specificity and reliability of activation. Alternative approaches have been suggested, including external triggers such as temperature or pH, to indicate infection or colonisation and activate cleaning mechanisms. A summary is shown in Table 1.

LIMITATIONS

While pharmacologically coated surfaces offer numerous benefits, they also come with several challenges and limitations that need to be addressed. Ensuring the biocompatibility and safety of pharmacological agents used in coatings is crucial. Some drugs may elicit allergic cause adverse effects in predisposed individuals. In addition, the long-term effects of exposure to these drugs on surrounding tissues need to be thoroughly evaluated. Achieving the optimal release kinetics of drugs from coated surfaces is challenging. The release rate must be carefully controlled to maintain therapeutic levels at the target site while minimising systemic exposure and potential side effects. Coatings must adhere securely to the underlying substrate and maintain their integrity under physiological conditions. Surface degradation, delamination or premature drug release can compromise the efficacy of the coating and increase the risk of complications such as thrombosis or infection. Pharmacologically coated surfaces must be compatible with the design and materials of medical devices. Manufacturers must demonstrate the safety, efficacy and consistency of the coating through rigorous preclinical and clinical testing, adding time and cost to the development process. The incorporation of pharmacological agents into coatings can increase the production costs of medical devices. Cost-effectiveness analyses are necessary to justify the added expense and demonstrate the value of pharmacologically coated surfaces compared to conventional treatments or devices. Patient variability in response to pharmacological treatments poses a challenge for pharmacologically coated surfaces. Factors such as genetic variability, comorbidities, efficacy and safety complicate the prediction of clinical outcomes. Addressing these challenges requires interdisciplinary collaboration among researchers, clinicians, engineers and regulatory agencies to develop innovative coating technologies that are safe, effective and commercially viable. Continued research and technological advancements are needed to overcome these limitations and realise the full potential of pharmacologically coated surfaces in improving patient care.

FUTURE DIRECTIONS

The future of pharmacologically coated surfaces holds promise for advancing medical treatments and improving patient outcomes. With advancements in genomics and precision medicine, there is increasing interest in developing pharmacologically coated surfaces tailored to individual patient profiles. Customised coatings could deliver specific drugs or combinations of drugs based on genetic markers, biomarkers or patient characteristics, optimising treatment outcomes and minimising side effects. Nanotechnology offers opportunities to engineer coatings with precise control over drug release kinetics, surface properties and targeting capabilities. Nanoparticles, nanofibers and nanostructured surfaces can enhance the efficacy and stability of pharmacological agents, enabling more efficient drug delivery and tissue integration. Bioactive coatings that promote tissue regeneration, angiogenesis or antimicrobial activity are gaining traction for various medical applications. Incorporating growth factors into coatings can stimulate healing and improve the biocompatibility of medical devices, particularly in orthopaedics and tissue engineering. Smart coatings equipped with sensors, stimuli-responsive materials or feedback mechanisms have the potential to revolutionise drug delivery and monitoring in real-time. Bioresorbable coatings that degrade over time and are absorbed by the body offer advantages in reducing long-term implant-related complications and eliminating the need for device removal surgeries. These coatings can be designed to deliver drugs during the critical early stages of healing before being safely metabolised and eliminated. Coatings designed to modulate the immune response, such as anti-inflammatory or immunomodulatory agents, hold potential for improving the biocompatibility and longevity of medical implants. Immune-modulating coatings could mitigate chronic inflammation, fibrosis or rejection reactions, enhancing tissue integration and device performance. Integrating regenerative medicine principles into coatings aims to create biomimetic environments that support tissue regeneration and repair. Coatings mimicking the extracellular matrix, bioactive peptides or growth factors can guide cell behaviour and promote tissue-specific regeneration, offering new solutions for regenerative therapies and organ transplantation. These future directions in pharmacologically coated surfaces reflect the ongoing efforts to develop innovative technologies that address unmet medical needs, enhance therapeutic outcomes and advance the field of medical device coatings. Collaboration among researchers, clinicians, industry partners and regulatory agencies will be essential to translate these advancements from the laboratory to clinical practice effectively.

METHODOLOGY

We performed a comprehensive search in databases such as PubMed, Scopus, Web of Science and Google Scholar, using search terms related to the interaction between pharmacologically coated surfaces, microbial activity and host immune responses (i.e. AMCs, immune response to coated biomaterials, pharmacological surface modification and infection control, bioactive coatings and host response, drug-eluting surfaces and immune modulation). We included studies involving both in vitro and in vivo models to gather insights into the mechanisms of interaction. Experimental research, clinical trials, case studies, qualitative analyses and review articles were included to provide a comprehensive perspective, with a particular focus on the role of coated surfaces in modulating immune responses and preventing microbial colonisation in biomedical and clinical contexts.

CONCLUSION

Surface coatings have revolutionised surgical applications by enhancing the performance, safety and biocompatibility of medical devices, implants and surgical instruments. These coatings offer various advantages, such as reducing friction and wear, preventing corrosion and promoting better instrument manoeuvrability during procedures. Biocompatible coatings minimise the risk of harmful reactions in the body, leading to fewer complications and faster recovery times for patients. In addition, AMCs play a critical role in reducing the risk of infections, particularly in the surgical setting, by preventing bacterial colonisation on medical devices. Moreover, pharmacologically coated surfaces introduce a new level of precision in therapy, allowing for controlled, localised drug delivery to prevent complications such as thrombosis or restenosis and improving the healing process. Graphene-based coatings represent a promising innovation in medical devices due to their excellent corrosion resistance, biocompatibility and potential to enhance bone growth. These materials, when applied to metallic implants, not only protect against degradation but also promote better integration with biological tissues. The development of such advanced coatings ensures that implants and surgical tools are more durable, effective and safer for long-term use. Moreover, anticorrosion and AMCs help to address issues associated with metallic biomaterials, such as ion release, corrosion and the risk of infection, providing a significant step forward in medical device technology. Finally, the evolving field of AMCs, particularly contact-active and biocide-releasing types, has immense potential in reducing HAIs and improving patient outcomes. Whether through the controlled release of biocides or direct contact with pathogens, these coatings offer a strategic method for minimising infection risks in surgical and medical settings. However, challenges remain in ensuring the sustainability and cost-effectiveness of these coatings in real-world applications. Future research into coatings with controlled release mechanisms and responsive properties could lead to even more efficient solutions, making surface coatings a cornerstone of next-generation medical device development. Surface coatings are poised to significantly impact the future of surgery and medical treatments by improving device functionality, patient safety and overall healthcare outcomes.