Physical Surface Modification Research Articles

Physical and chemical surface modification by laser polishing of CuZn42 parts produced by laser powder bed fusion

The widespread use of Cu-Zn alloys containing lead (Pb) in plumbing applications poses significant health risks due to potential Pb leaching into drinking water. In response to international legislation aimed at reducing or eliminating Pb in metal alloys, there is an increasing demand for environmentally friendly brass. In this experimental work, authors show that during the Laser Beam Powder Bed Fusion (PBF-LB) process of the CuZn42 (CW510L) alloy, small particles only a few microns large mixed with large particles that are hundreds of microns in size, are spattered from the material. Large particles show average Zn/Cu ratio around 0.22, while for small particles it increases up to 3, against a nominal value of 0.72 for the CW510L alloy. The fallout of such particles on the produced part enriches surface of Zn, thus altering the surface chemical composition with an increase in Zn concentration beyond the acceptance limit of 43 at.%. To restore the standard chemical composition of the surface, a treatment based on the ablation of the surface material by a laser beam was proposed. Results clearly show that, after the laser treatment, the chemical composition of the surface is completely restored, and the standard properties recovered.

Unlocking the potential of titanium and its alloys: A mini-review on innovative surface modification techniques

Titanium and its alloys are widely utilized in various fields, such as biomedical and aerospace, and in other industrial applications. However, its surface modification is essential to further enrich its properties to enhance its effectiveness. Researchers across the globe are continuously working on a variety of surface modification methods to enhance the properties of titanium and its alloys. This paper presents a comprehensive review of surface modification methods utilized for titanium and its alloys. Some of the important modification techniques discussed in this paper includes mechanical, chemical, electrochemical, thermal, and physical surface modification methods. This paper also provides insights into surface modification methods in terms of improving corrosion and wear resistance, biocompatibility, and hardness of titanium and its alloys.

Enhancing camptothecin loading and release control through physical surface modification of organosilica nanoparticles with polyethylene glycol

The surface modification of nanoparticles holds the potential to enhance the loading capacity of drug molecules and regulate their release, making it possible to exploit the differences between tumor and normal cells. To this end, the surfaces of tetrasulfide-based phenylene-containing biodegradable periodic mesoporous organosilica (BPMO) nanoparticles (designated P4S) are modified herein with a hydrophilic and biocompatible polyethylene glycol (PEG) polymer. The PEG coating is optimized by adjusting the PEG concentration during synthesis, thus resulting in a significant increase in the nanoparticle stability. Furthermore, PEG modification enhances the nanoparticles' camptothecin (CPT) loading capacity. Drug release assessments under physical and acidic pH conditions demonstrate the pH-responsive properties of the P4S nanoparticles upon PEG functionalization, which results in increased drug release at low pH, along with enhanced cellular uptake potential. Notably, the cytotoxicity of CPT against HepG2 cancer cells is significantly improved when loaded into the P4S-PEG nanoparticles. These findings reveal the efficacy of PEG surface modification of the drug-delivery material in augmenting the activity of CPT, with promising prospects for clinical applications.

Physical and Chemical Surface Modification of Recycled Polystyrene Films for Improved Triboelectric Properties

Polystyrene (PS) is a very common material in packaging. In this study, it is recycled by turning it into energy harvesting devices: triboelectric generators. Herein, heat‐pressed films of recycled PS are formed and their surfaces are modified physically and chemically. The triboelectric properties of the films are determined using a dynamic testing machine, and the performance of the triboelectric generators is evaluated with a high‐speed contact–separation system. The developed charge density of the triboelectric generator increases two orders of magnitude—from 0.03 to 1.52 nC cm−2—by combining these surface modification methods. Such high values of charge density enable the production of single material triboelectric generators.

Application of PLGA in Tumor Immunotherapy.

Biodegradable polymers have been extensively researched in the field of biomedicine. Polylactic-co-glycolic acid (PLGA), a biodegradable polymer material, has been widely used in drug delivery systems and has shown great potential in various medical fields, including vaccines, tissue engineering such as bone regeneration and wound healing, and 3D printing. Cancer, a group of diseases with high mortality rates worldwide, has recently garnered significant attention in the field of immune therapy research. In recent years, there has been growing interest in the delivery function of PLGA in tumor immunotherapy. In tumor immunotherapy, PLGA can serve as a carrier to load antigens on its surface, thereby enhancing the immune system's ability to attack tumor cells. Additionally, PLGA can be used to formulate tumor vaccines and immunoadjuvants, thereby enhancing the efficacy of tumor immunotherapy. PLGA nanoparticles (NPs) can also enhance the effectiveness of tumor immunotherapy by regulating the activity and differentiation of immune cells, and by improving the expression and presentation of tumor antigens. Furthermore, due to the diverse physical properties and surface modifications of PLGA, it has a wider range of potential applications in tumor immunotherapy through the loading of various types of drugs or other innovative substances. We aim to highlight the recent advances and challenges of plga in the field of oncology therapy to stimulate further research and development of innovative PLGA-based approaches, and more effective and personalized cancer therapies.

Gallium‐Based Liquid Metal Composites and the Continuous Forming Methods

Due to the dual nature of metal and fluid, gallium‐based liquid metals with a low melting point at or around room temperature have gained growing interest recently. Although more properties of gallium are developed, their intrinsic properties are not able to meet the increasing requirement from the scientific and industrial community. To broaden its applications, many kinds of gallium‐based liquid metal composites are prepared and applied in the cutting‐edge fields like biomedical engineering, flexible robots, heat management, and so on. To summarize the latest progress and promote development, this review summarizes the recent progress of liquid metal composites and the continuous forming methods recently, including the physical and chemical properties of gallium‐based liquid metal, composites prepared through physical doping and surface modification, and the continuous forming approaches. Further outlook including expectations and challenges of gallium‐based liquid metal composites is also presented.

Critical role of the composition of the cell culture medium on cell attachment and viability on PLA biocomposite scaffolds under in vitro assay conditions

In tissue engineering applications 3D scaffolds undertake the function of the native extracellular matrix (ECM) for cell attachment, survival, proliferation, and differentiation. For successful long-term implementation scaffolds need to mimic the ECM in vitro and in vivo. Many studies have focused on protein adsorption as the most critical factor for cell attachment. To improve protein adsorption on polymeric scaffolds various physical and chemical surface modification techniques, such as changing surface porosity, surface energy, and introducing various functional surface chemical groups have been investigated. It is well studied and documented that complex interactions between the biomaterial surface and the cell culture components in in vitro assay conditions define the scaffold performance. In this study influence of in vitro assay components on HepG2 liver cell attachment and proliferation on 3D printed poly(lactic acid) (PLA) scaffolds coated with various polymeric electrospun webs were investigated. MTT assays were performed on the scaffolds by using 3 different cell culture media; (i) basal cell culture medium (DMEM), (ii) DMEM supplemented with 10% albumin, and (iii) DMEM supplemented with 10% fetal bovine serum (FBS). Results obtained have shown dramatic improvement in cell attachment and proliferation in DMEM supplemented with 10% FBS when compared with DMEM and DMEM containing 10% albumin. Our findings clearly demonstrate synergistic effects of all bioactive components present in the FBS medium in significantly improving the HepG2 cell attachment and proliferation on polymeric scaffolds under in vitro conditions, regardless of the substrate structure, composition, and surface properties.

Antifouling strategies for electrochemical sensing in complex biological media.

Surface fouling poses a significant challenge that restricts the analytical performance of electrochemical sensors in both in vitro and in vivo applications. Biofouling resistance is paramount to guarantee the reliable operation of electrochemical sensors in complex biofluids (e.g., blood, serum, and urine). Seeking efficient strategies for surface fouling and establishing highly sensitive sensing platforms for applications in complex media have received increasing attention in the past. In this review, we provide a comprehensive overview of recent research efforts focused on antifouling electrochemical sensors. Initially, we present a detailed illustration of the concept about biofouling along with an exploration of four key antifouling mechanisms. Subsequently, we delve into the commonly employed antifouling strategies in the fabrication of electrochemical sensors. These encompass physical surface topography (micro/nanostructure coatings and filtration membranes) and chemical surface modifications (PEG and its derivatives, zwitterionic polymers, peptides, proteins, and various other antifouling materials). The progress in antifouling electrochemical sensors is proposed concerning the antifouling mechanisms as well as sensing capability assessments (e.g., sensitivity, stability, and practical application ability). Finally, we summarize the evolving trends in the field and highlight some key remaining limitations.

Surface modification strategies of 304 austenitic stainless steel plate with different micromorphology and composition for improved mechanical interlocking and chemical bonding in metal–epoxy joints

304 austenitic stainless-steel (SS) strip-based carbon fiber metal laminates (CFMLs) have raised significant concerns, in terms of their mechanical performance. On top of that, the hybrid laminates’ interlamination performance is vital in regulating their failure patterns. Along these lines, in this work, SS strips with regulatable micromorphology and composition were obtained by using physical and chemical surface modification strategies, including polishing, acid etching, anodization, and thermal treatment. The shear strength of the treated-SS/epoxy single lap joints (two treated-SS strips bonded by the epoxy resin via hot curing process) was systematically explored, and the origins of the enhancement mechanism were attributed to the resulting surface microstructure, as well as the possible chemical reactions between the treated surface and the curing agent. The etching-anodizing-thermally treated-SS (EAT-SS)/epoxy joint exhibited the maximum shear strength (16.04 MPa) and work of fracture (5.85 kJ·m−2) due to the substantial cohesive failure pattern of the epoxy. The encouraging enhancement was mainly attributed to the synergistic effect of the micro-annular pit and the nanoporous array structure of the EAT-SS surface. These effects induced a significant mechanical interlock and a plausible chemical reaction at the interface, which led to improved bonding strength between the epoxy and treated-SS surface. Overall, in this work, it was demonstrated that the combination of the anodization and thermal treatment can effectively improve the interlamination bonding properties between the SS strip and the epoxy resin due to the combination effect of mechanical interlocking and chemical bonding.

A micro-dome array triboelectric nanogenerator with a nanocomposite dielectric enhancement layer for wearable pressure sensing and gait analysis.

The practical application of a triboelectric nanogenerator (TENG) as a self-powered sensor and an energy harvester is constrained by the need for a wide sensitivity range, significant output power, and structural flexibility. However, most research has focused on physical and chemical surface modifications of the charge-generating layer to enhance the TENG performance. Improving the charge storage ability could otherwise further enhance the overall performance. Here, we propose a flexible TENG design that incorporates a micro-dome array Ecoflex as the tribo-negative layer, coupled with a dielectric enhancement layer composed of a carbon black/Ecoflex composite. The addition of the CB/Eco composite layer to the micro-dome array triboelectric layer enhanced the output voltage performance by forming numerous micro capacitors within the dielectric layer. Furthermore, oxygen-containing fluorocarbon plasma treatment of the micro-dome array increased the surface energy, enhancing the interaction between the triboelectric layers. This leads to an enhancement in the output voltage and energy efficiency, exhibiting a power density of 197.4 mW m-2. The pressure sensitivity of the TENG was systematically investigated, demonstrating 2.57 V kPa-1 in the low-pressure range (0.612 to 8.58 kPa) and 1.70 V kPa-1 in the high-pressure range (8.58 to 20.83 kPa). Additionally, the encapsulated TENG sensor with spacers was integrated into insoles for self-powered gait analysis, providing real-time insights into walking patterns and frequencies. Exploring the TENG's energy harvesting capability revealed a peak-peak voltage of 89.4 V when two TENGs are connected in series. The comprehensive performance characterization of the TENG demonstrates its promising applications in wearable, self-powered sensing, and energy harvesting systems.

Research Progress of Aluminum Alloy Welding/Plastic Deformation Composite Forming Technology in Achieving High-Strength Joints.

Fusion welding causes joint deterioration when joining aluminum alloys, which limits the use of aluminum alloy components in high-end equipment. This paper focuses on an overview of how to achieve high-strength aluminum alloy welded joints using welding/plastic deformation composite forming technology. The current technology is summarized into two categories: plastic deformation welding and plastic deformation strengthening. Plastic deformation welding includes friction stir welding, friction welding, diffusion welding, superplastic solid-state welding, explosive welding, and electromagnetic pulse welding. Plastic deformation strengthening refers to the application of plastic deformation to the weld seam or heat-affected zone, or even the whole joint, after welding or during welding, including physical surface modification and large-scale plastic deformation technology. Important processing parameters of plastic deformation welding and their effects on weld quality are discussed, and the microstructure is described. The effect of plastic deformation strengthening technology on the microstructure and performance evolution, including the hardness, tensile strength, fatigue property, residual stress, and hot cracking of aluminum alloy welded joints, and its evolution mechanism are systematically analyzed. Finally, this paper discusses the future development of plastic deformation strengthening technology and anticipates growing interest in this research area.

Electrospun PAN/PEG Nanofibrous Membrane Embedded with a MgO/gC3N4 Nanocomposite for Effective Bone Regeneration.

Developing biomaterial scaffolds using tissue engineering with physical and chemical surface modification processes can improve the bioactivity and biocompatibility of the materials. The appropriate substrate and site for cell attachment are crucial in cell behavior and biological activities. Therefore, the study aims to develop a conventional electrospun nanofibrous biomaterial using reproducible surface topography, which offers beneficial effects on the cell activities of bone cells. The bioactive MgO/gC3N4 was incorporated on PAN/PEG and fabricated into a nanofibrous membrane using electrospinning. The nanocomposite uniformly distributed on the PAN/PEG nanofiber helps to increase the number of induced pores and reduce the hydrophobicity of PAN. The physiochemical characterization of prepared nanoparticles and nanofibers was carried out using FTIR, X-ray diffraction (XRD), thermogravimetry analysis (TGA), X-ray photoelectron spectroscopy (XPS), and water contact angle measurements. SEM and TEM analyses examined the nanofibrous morphology and the structure of MgO/gC3N4. In vitro studies such as on ALP activity demonstrated the membrane's ability to regenerate new bone and healing capacity. Furthermore, alizarin red staining showed the increasing ability of the cell-cell interaction and calcium content for tissue regeneration. The cytotoxicity of the prepared membrane was about 97.09% of live THP-1 cells on the surface of the MgO/gC3N4@PAN/PEG membrane evaluated using MTT dye staining. The soil burial degradation analysis exhibited that the maximum degradation occurs on the 45th day because of microbial activity. In vitro PBS degradation was observed on the 15th day after the bulk hydrolysis mechanism. Hence, on the basis of the study outcomes, we affirm that the MgO/gC3N4@PAN/PEG nanofibrous membrane can act as a potential bone regenerative substrate.

Surface modification of Nano cellulose: The path to advanced uses of smart and sustainable bio-material

In order to develop sophisticated applications for intelligent and sustainable biomaterials, our work focuses on the surface modification of nanocellulose. Nanocellulose has the ability to be modified to improve its surface characteristics, making it appropriate for a variety of uses in industries including biomedicine, packaging, textiles, and water treatment. There have been discussions on a number of physical and chemical surface modification approaches, including mechanical treatment, high-pressure homogenization, and chemical functionalization. The study also highlights the results of different characterization methods that were employed to examine the surface-modified nanocellulose. The review addresses the difficulties in integrating nanocellulose into many applications, despite its potential, including manufacturing scale-up, standardisation, and toxicity issues. The article's conclusion highlights the need for continuing research and development of nanocellulose-based materials in order to meet these obstacles and offer long-term solutions to a range of social issues.

Remedy Publications LLC., | http://surgeryresearchjournal.com World Journal of Surgery and Surgical Research 2023 | Volume 6 | Article 15001 Physical Modification of a Gelatin Sponge Creates a Very Adhesive, Rapidly Absorbable, Blood-Free Hemostat

Background: An effective hemostat not only needs to stop the bleeding whilst it is held in place but importantly, it must stay there securely during the perioperative recovery phases. As patients move during the recovery period, several forces can act on the hemostat leading to its displacement and possible postoperative hemorrhage. Adhesive hemostats have been developed to prevent this, but many contain human blood components or are prohibitively expensive for widespread use. This study evaluated a physical surface modification of a plain gelatin sponge with no additives (chemical/biologic), designed to securely adhere to bleeding tissue and create a long-lasting hemostatic matrix (TenaTac®, Selentus Science, UK). Methods: Adhesion and hemostasis were tested in a standard leporine hepatic bleeding model against the adhesive hemostats, TachoSil® and Hemopatch®. Absorption was tested in a porcine hepatic implantation model against plain gelatin sponge. Results: TenaTac was very well tolerated in the porcine model and was completely reabsorbed by day 14. TenaTac demonstrated a 69% improvement in adhesion over TachoSil (p<0.001). Hemostasis was also significantly better than TachoSil at the 6- & 9-min endpoints (p=0.016 & p=0.002). With systemic heparinization (300 u/kg) TenaTac’s adhesion score was 42.5% higher than non-heparinized TachoSil (p=0.003). After delivery through a laparoscopic cannula, the hemostasis and adhesive capabilities were not different from Hemopatch (p>0.05 for all). Conclusion: Physical surface modification of a gelatin sponge has resulted in a rapidly absorbable hemostat that demonstrates superior adhesion and hemostasis to other advanced hemostats.

Axial compressive behaviour and physical characteristics of high strength self-compacting geopolymer concrete (HSGC) columns exposed to elevated temperature

The growing demand in the utilization of the cement has increased carbon emissions, necessitating the adoption of new technologies that are eco-friendly. Geopolymer concrete (GC) is a viable alternative to traditional cement-based concrete, with superior mechanical properties and sustainable performance. However, research on the elevated temperature exposure of geopolymer paste, mortar, and concrete is limited, particularly with respect to high-strength and self-compacting geopolymer concrete. This study aims to investigate the performance of high-strength self-compacting geopolymer concrete (HSGC) at room temperature and elevated temperatures up to 1029 ℃. The investigation is carried out consisting of two strength grades: normal strength GC and HSGC. Tests are conducted on both HSGC cube and column specimens to examine the residual compressive strength (CS) and axial compression performance of the concrete before and after exposure to elevated temperature. The fresh physical characteristics of HSGC are examined following EFNARC guidelines. Post-fire performance is analysed through physical observation, surface modification, crack pattern, weight loss (WL), and residual CS of HSGC samples. Load-Moment (P-M) interaction curves are developed to predict the ultimate load and ultimate moment capacity of the HSGC columns before and after exposure to elevated temperature. The ductility of heated and unheated HSGC columns is found to be almost same. Microstructural analysis, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) are performed to examine the internal morphology of the HSGC samples before and after exposure to elevated temperature. Furthermore, a life-cycle assessment (LCA) is conducted to compare the cost of HSGC production with conventional cement-based concrete. The analysis indicates that HSGC emits 6.15% less CO2-e than its counterpart cement-based concrete.

Nanotextured porous titanium scaffolds by argon ion irradiation: Toward conformal nanopatterning and improved implant osseointegration.

Stress shielding and osseointegration are two main challenges in bone regeneration, which have been targeted successfully by chemical and physical surface modification methods. Direct irradiation synthesis (DIS) is an energetic ion irradiation method that generates self-organized nanopatterns conformal to the surface of materials with complex geometries (e.g., pores on a material surface). This work exposes porous titanium samples to energetic argon ions generating nanopatterning between and inside pores. The unique porous architected titanium (Ti) structure is achieved by mixing Ti powder with given amounts of spacer NaCl particles (vol % equal to 30%, 40%, 50%, 60%, and 70%), compacted and sintered, and combined with DIS to generate a porous Ti with bone-like mechanical properties and hierarchical topography to enhance Ti osseointegration. The porosity percentages range between 25% and 30% using 30 vol % NaCl space-holder (SH) volume percentages to porosity rates of 63%-68% with SH volume of 70 vol % NaCl. Stable and reproducible nanopatterning on the flat surface between pores, inside pits, and along the internal pore walls are achieved, for the first time on any porous biomaterial. Nanoscale features were observed in the form of nanowalls and nanopeaks of lengths between 100 and 500 nm, thicknesses of 35-nm and heights between 100 and 200 nm on average. Bulk mechanical properties that mimic bone-like structures were observed along with increased wettability (by reducing contact values). Nano features were cell biocompatible and enhanced in vitro pre-osteoblast differentiation and mineralization. Higher alkaline phosphatase levels and increased calcium deposits were observed on irradiated 50 vol % NaCl samples at 7 and 14 days. After 24 h, nanopatterned porous samples decreased the number of attached macrophages and the formation of foreign body giant cells, confirming nanoscale tunability of M1-M2 immuno-activation with enhanced osseointegration.

Elucidating the effects of dispersion methods on agglomerated nano silica particles in aqueous environment

A zero-dimensional Nano silica (NS) particle possess a wide range of application in multi-variant fields due to its size, amorphous nature and silica content in spite of its hydrophilic and hydrophobic behaviour. These nano particles are synthesized and commercially supplied in the size range of 1–100 nm with high Specific Surface Area (SSA). Due to agglomeration, these NS particles are sized between 1 and 100 μm which in turn reduces its SSA and thereby limiting its efficient utilisation. As a pragmatic solution, the current study involves in defining the suitable dispersion method for NS particles in aqueous environment. The effects of both mechanical and physical surface modification of nano particles using Superplasticizer (SP) since the incorporation of NS particles that aim at cementitious system are investigated. NS particles acts as nucleation seeds in cement hydration which directly relay on its particle size. The mechanical modification methods such as Ultrasonication and high shear mixer are employed to reduce the agglomerates size. Whereas the effect of steric (electrostatic mechanism) and Vander Waals attraction between the deagglomerated particles are studied. The stability and the size histogram of deagglomerated nano particles are thoroughly assessed with Dynamic Light Scattering (DLS) technique. From the findings, it is interpreted that the combination of mechanical and surface modification effectively reduces the size of agglomerates as well as the intensity of surface attractive forces between the particles with respect to its dosage in aqueous medium.

Flexibly designable wettability gradient for passive control of fluid motion via physical surface modification

Modified solid surfaces exhibit unique wetting behavior, such as hydrophobicity and hydrophilicity. Such behavior can passively control the fluid flow. In this study, we experimentally demonstrated a wettability-designable cell array consisting of unetched and physically etched surfaces by reactive ion etching on a silicon substrate. The etching process induced a significant surface roughness on the silicon surface. Thus, the unetched and etched surfaces have different wettabilities. By adjusting the ratio between the unetched and etched surface areas, we designed one- and two-dimensional wettability gradients for the fluid channel. Consequently, fine-tuned channels passively realized unidirectional and curved fluid motions. The design of a wettability gradient is crucial for practical and portable systems with integrated fluid channels.

Surface Functionalization of (Pyrolytic) Carbon—An Overview

This review focuses on techniques for modifying the surface of carbon that is produced from sustainable resources, such as pyrolytic carbon. Many of these materials display high specific surface area and fine particle distribution. Functionalization of a surface is a commonly used approach in designing desired surface properties of the treated material while retaining its bulk properties. Usually, oxidation is a primary step in carbon functionalization. It can be performed as wet oxidation, which is a type of chemical surface modification. Wet oxidation is usually performed using nitric acid and hydrogen peroxide, as well as using hydrothermal and solvothermal oxidation. On the other side, dry oxidation is representative of physical surface modification. This method is based on corona discharge and plasma oxidation which are promising methods that are in line with green chemistry approaches. Whilst the oxidation of the carbon surface is a well-known method, other chemical modification techniques, including cycloadditions and various radical reactions on graphene layers, are presented as an alternative approach. Regarding secondary functionalization, coupling organosilanes to activated carbon is a common technique. Organosilanes bearing reactive groups present a bridge between inorganic species and polymer systems, e.g., epoxy and polyurethane resins, and facilitate the use of carbonaceous materials as reinforcing components for polymers and thermosetting resins. Along with the presented functionalization methods, this review also provides an overview of new applications of modified (i.e., functionalized) carbon materials, e.g., for the building industry, wastewater treatment, semiconducting materials and many more.

Hydrophilic Modification Strategies to Enhance the Surface Biocompatibility of Poly(dimethylsiloxane)‐Based Biomaterials for Medical Applications

AbstractPoly(dimethylsiloxane) (PDMS) has been widely employed in biomedical disciplines due to its several advantages, including biocompatibility, nontoxicity, and low‐cost preparation. However, the intrinsic hydrophobicity of this material encourages biofouling and reduces cell regulation capacity, thereby limiting its biomedical applicability. The purpose of this study is to explore the surface modification and functionalization of PDMS and PDMS‐based biomaterials to improve their properties for biomedical applications. The content of this review is organized based on physical and chemical surface modification strategies to improve surface hydrophilicity to enhance antibiofouling and the regulation of immunomodulation and cell modulation on the surface of PDMS and PDMS‐based biomaterials. Future developments in this area are also discussed.