Hydrophilic Materials Research Articles

Polymersomes: Beyond Basics‐Synthesis, Stimuli Response and Biomedical Applications

AbstractPolymersomes, also known as polymeric vesicles, have high potential in the field of biomedicines due to their high stability and ability to carry hydrophilic and hydrophobic materials to the targeted sites without any loss. The self‐assembly of amphiphilic block copolymers into hollow spherical structures, known as polymersomes, has opened up new frontiers in biomedicine and other bio‐related applications. These structures harness the unique properties of biopolymers such as polyethylene glycol (PEG), polycaprolactone (PCL), and polypeptides, which contribute to their biocompatibility and functionality. The need for efficient materials for applications in the field of targeted drug delivery, theranostics, and bio‐imaging is increasing day by day so that scientists are in search of efficient polymersomes by making modifications in their structures. This review outlines various block copolymers from which polymersomes can be made, the types of polymersomes, the ways to prepare the materials along with the biomedical applications that the polymersomes can be opted for. Here we discuss about self‐assembly techniques like solvent switch, microfluid, pH tuning and polymerization induced self‐assembly. The present paper provides an overview of stimuli‐responsive polymersomes. Towards the end of the review, several applications of polymersomes are covered, such as drug administration, imaging, theranostics, and usage as nanoreactors.

Polyvinylidene fluoride-alkali lignin blend: A new candidate for membranes development

New blend membranes consisting of a tuned ratio of polyvinylidene fluoride (PVDF) and alkali lignin (AL) were studied. Through the use of a green solvent like dimethyl sulfoxide, effective mixing between PVDF and AL was achieved, leading to the development of highly hydrophilic membranes with robust mechanical stability. Characterization methods confirmed the suitability of the blend for membrane preparation and its hydrophilic nature.A key aspect of the strategy involved hydrophilizing PVDF during the preparation process by blending it with AL in the pot. This approach aimed to streamline production by reducing the number of steps compared to post-treatment methods such as grafting or coating. The presence of hydrophobic/hydrophilic groups in the AL structure addressed the challenge of compatibility between PVDF and conventional hydrophilic polymers, enhancing interaction between the components.The resulting hydrophilic material exhibited improved pure water permeance and demonstrated resistance to irreversible fouling. The membrane's ability to process wastewater streams and its resistance to fouling was demonstrated by separating stable and uniform submicron oil-in-water emulsions with high rejection (>99.9 %) up to a volume reduction factor (VRF) of 7.7.

Towards ultra-stable and dendrite-suppressed Li-metal batteries: Ion-regulating graphene-modified separators

The practical application of metallic lithium (Li) anodes is hindered by nonuniform Li deposition/dissolution, as well as poor electrochemical reversibility during cycling. To address these challenges, surface modification of polymer separators with functional materials has been extensively explored. In this study, two distinct surface-modifying layers composed of MnOx and polydopamine (PDA) are applied to modify the surface of graphene-coated polypropylene separators (G@PP). Both MnOx and PDA, which are formed through the graphene layer, significantly enhance the intrinsic electrolyte wettability of G@PP, resulting in a homogeneous Li-ion flux. Furthermore, the lithiophilic properties revealed by DFT and COMSOL analyses synergize with the hydrophilic characteristics, resulting in a more stable electrochemical performance in Li-metal batteries (LMBs). The enhanced electrolyte permeability of the coating layer allows Li–Cu cells with MnOx-modified graphene-coated PP (MG@PP) and PDA-modified graphene-coated PP (PG@PP) separators to exhibit significantly improved cycle stability compared with Li–Cu cells with G@PP separators. Interestingly, Li–S cells equipped with MG@PP and PG@PP separators exhibit also enhanced electrochemical performance compared with Li–S cells with G@PP separators. These results highlight that surface engineering of separator-coating materials along with hydrophilic and lithiophilic materials enhances both long-term cycle stability and electrochemical kinetics in LMBs.

Review of The Innovative Medication Delivery System: The Cubosome

Cubosomes, also known as bicontinuous cubic phase liquid crystals, are nanoparticles with a specific ratio of amphiphilic lipids as their major constituents. Cubosomes are typically created by hydrating a surfactant or polar lipid that produces a cubic phase and then dispersing it into smaller particles. They operate with solids similar to rheology peculiarities of practical use. They have carvenous (honeycomb) structures that are tightly packed and twisted into three-dimensional bilayers, and they are thermodynamically stable. They can load more drugs because of this type of sophisticated structure. Cubosomes are capable of encapsulating hydrophobic, hydrophilic, and amphiphilic materials. Cubosomes can make drugs that aren't very soluble more soluble. Biocompatible and bioadhesive cubosomes dispersions are available. Due to their characteristics, cubosomes are adaptable systems that can be managed by several ways, including parenterally, percutaneously, and orally. Few researchers have looked into the possibility of cubosomes as delivery methods despite the fact that cubosomes structure has been studied using electron microscopy, light scattering, x-ray, and NMR.

Catechol-Fe(III) complexes modified PVDF membrane for hazardous pollutants separation and antifouling properties

Organic pollutants, such as toluene and xylene, in industrial wastewater negatively impact the environment. Membrane treatment is one of the best methods to reduce impurities in wastewater. Existing membranes that coat the water surface with hydrophilic material only effectively resist the initial fouling, resulting in poor oil and water selectivity. Here we report a simple and efficient method to enhance the water flux and antifouling properties of polyvinylidene fluoride (PVDF) membranes. This method involves developing and applying Catechol-Fe(III) complexes with a rough surface to the PVDF surface. Forming Catechol-Fe(III) complexes on the surface better anchors them to the membrane than the dip-coating method. The PVDF membranes with rough Catechol-Fe(III) complexes are superoleophobic, with an oil contact angle of 152 ° and high permeability, with pure water flux of 10487 Lm‐2h‐1bar‐1 and 1 wt% toluene in water emulsion flux of 4697 Lm‐2h‐1bar‐1. Overall, the straightforward manufacturing process, increased permeability, and outstanding antifouling capabilities of the PVDF membrane incorporating rough nanoparticles offer promising prospects for designing and implementing suitable membranes for oil in water emulsion separation applications.

Recent Advances for Wastewater Treatment on Polyvinylidene Fluoride-Based Membrane: A Review

The development of scalable membrane-based separation processes has attracted considerable interest on laboratory and industrial scales. Polyvinylidene fluoride (PVDF) is one of the most widely used fluoropolymer materials for membrane fabrication due to its excellent mechanical strength, good thermal stability and chemical resistance as well as aging resistance. However, the hydrophobic nature of PVDF has resulted in serious membrane fouling during the filtration process. From the past decade, the embedment of hydrophilic materials in/on PVDF-based membranes can significantly alter the membrane’s morphology and surface properties. Therefore, based on most articles retrieved from Web of Science, Scopus, Google Scholar, etc., this article provides the overview of the recent development of PVDF-based membranes during the recent several decades. The detailed information regarding PVDF as a polymer material as well as the main challenge in the development of PVDF-based membranes with better performance was summarised. Moreover, the factors influencing membrane fouling including surface hydrophilicity, roughness and charge are also addressed. Then, the PVDF-based membrane preparation and its recent modification via the blending method were discussed. Finally, the overview and future perspective of PVDF-based membrane development are reviewed. Overall, it can be concluded that PVDF-based membranes have great potential for further advances towards the development of membrane technologies for the future.

Hydrophilic materials based on hydrogel polymers for enrichment of glycopeptides from serum of colorectal cancer patients.

In this work, a composite hydrogel material consisting of chitosan-based composite hydrogel was prepared by a simple and rapid synthetic method and will be named three-dimensional (3D)-IL-COF-1@CS hydrogel. Possessing a stable 3D network structure and outstanding hydrophilicity, the novel hydrogel is capable of capturing glycopeptides. The 3D-IL-COF-1@CS hydrogel showed good sensitivity (0.1 fmol/µL) and selectivity (1:2000). In addition, 19 glycopeptides were captured in standard samples. In the analysis of human serum, 148 glycopeptides assigned to 72 glycoproteins were assayed in the serum of normal individuals, and 245 glycopeptides corresponding to 100 glycoproteins were found in the serum of colorectal cancer (CRC) patients. More importantly, several functional programs based on Gene Ontology analysis supported molecular biological processes that may be relevant to the pathogenesis of CRC, including aging, fibrinogen complex, and arylesterase activity. The low cost, simplicity, rapid synthesis, and good enrichment performance have a great future in glycoproteomics analysis and related diseases.

Chitosan membranes incorporating Aloe vera glycolic extract with joint synthesis of silver nanoparticles for the treatment of skin lesions.

New wound dressings based on polymeric membranes have been widely exploited for clinical applications to assist in the healing process and prevent additional complications (e.g., bacterial infections). Here we propose the development of a new production method of polymeric membranes based on chitosan, incorporating glycolic extract of Aloe vera with joint synthesis of silver nanoparticles for use as a new bioactive dressing. The membranes were obtained by casting technique, and their morphological, physicochemical characteristics, degree of swelling, degradation profile and antimicrobial activity evaluated. Morphological analyzes confirmed the synthesis and presence of silver nanoparticles in the polymeric membrane. The chemical compatibility between the materials was demonstrated through thermal analysis (TGA and DSC) combined with ATR-FTIR tests, showing the complexation of the membranes (Mb-Ch-Ex.Av-NPs). All membranes were characterized as hydrophilic material (with a contact angle (ө) < 90°); however, the highest degree of swelling was obtained for the chitosan. (Mb-Ch) membrane (69.91 ± 5.75%) and the lowest for Mb-Ch-Ex.Av-NPs (26.62 ± 8.93%). On the other hand, the degradation profile was higher for Mb-Ch-Ex.Av-NPs (77.85 ± 7.51%) and lower for Mb-Ch (57.60 ± 2.29%). The manufactured bioactive dressings showed activity against Escherichia coli and Staphylococcus aureus. Our work confirmed the development of translucent and flexible chitosan-based membranes, incorporating Aloe vera glycolic extract with joint synthesis of silver nanoparticles for use as a new bioactive dressing, with proven antimicrobial activity.

Research on the effect of DES properties on the preparation of h-BN nanosheets by electrochemical-liquid phase exfoliation method

Hexagonal boron nitride (h-BN) with a large specific surface area and unique optoelectronic properties has good application prospects in many fields. The liquid phase exfoliation method is considered the most promising method for achieving controllable preparation of boron nitride nanosheets (BNNSs), but the low-cost, relatively environmentally friendly and efficient liquid phase exfoliation is still difficult to achieve. Choosing a suitable solvent system is the key to achieving efficient exfoliation. Deep eutectic solvents (DESs) have the advantages of simple synthesis, low cost, high thermal and chemical stability and strong biocompatibility and are expected to be green solvents for preparation of BNNSs. In this paper, it was found that the properties of DESs and its interaction with h-BN had a significant impact on the electrochemical exfoliation of h-BN. The intercalation effect of DES and the compatibility between DES and h-BN were the main factors affecting the yield, while the quality of BNNSs mainly depended on the decomposition and expansion effect of DES. This rule also can be applied to prepare highly conductive and hydrophilic two-dimensional material Ti-MXene. This research explores the structure–activity relationship between two-dimensional materials and DESs, and provides a theoretical basis for the environmentally friendly and efficient preparation of two-dimensional materials using DESs as exfoliation solvents.

High Hydrophilic and Antibacterial Efficient UV-Curable Silicone-Containing Choline Chloride Quaternary Ammonium Salts Functionalized Materials.

Antibacterial materials with high hydrophobicity have drawbacks such as protein adsorption, bacterial contamination, and biofilm formation, which are responsible for some serious adverse health events. Therefore, antibacterial materials with high hydrophilicity are highly desired. In this paper, UV-curable antibacterial materials are prepared from silicone-containing Choline chloride (ChCl) functionalized hyperbranched quaternary ammonium salts (QAS) and tri-hydroxylethyl acrylate phosphate (TAEP). The materials show high hydrophilic performance because their water contact angle is as low as 19.3°. The materials also exhibit quite high antibacterial efficiency against S. aureus over 95.6%, fairly high transmittance over 90%, and good mechanical performance with tensile strength as high as 6.5MPa. It reveals that it is afeasible strategy to develop antibacterial materials with low hydrophobicity from silicone-modified ChCl-functionalized hyperbranched QAS.

Natural polymers-based separation membrane for high-efficient separation of oil water mixture

In recent years, the problem of oil pollution represented by industrial oily waste occurs frequently, and the general hydrophilic filtration materials are facing the problems of clogging and poor hydrophilicity, so the hydrophilic hydrogel materials have received some attention, but the related research can’t balance the filtration materials related to the needs of high efficiency, rapidity and stability. In recent years, research on physically cross-linked hydrogels has been developed. We designed a hydrogel made of natural polymers and modified materials including cotton cloth and copper foam by coating or dip coating, and prepared physically crosslinked hydrogel-modified filtration materials, in which the pore size of 10 μm and a superhydrophilic/underwater superoleophilic wettability with an oil contact angle of more than 150° underwater can realize a water flux of more than 106 L·m−2·h−1 and an oil-water flux of more than 99 % efficiency. The oil-water separation efficiency higher than 99 %. Through the action of its ionic electrolyte, it can decompose emulsions containing different surfactants with an efficiency of more than 99 %, and it still possesses high hydrophilicity and separation efficiency even when immersed in pH=1 acid solution for 1 h, and it still possesses high water flux and separation efficiency even when abraded more than 100 times. The materials used are all non-toxic and are not harmful to the environment after segregation. The physically cross-linked hydrogel prepared in this experiment provides a method for realizing oily wastewater purification without secondary pollution, with high efficiency, rapidity and stability, and has a high potential for further development.

Designing Co-coordinated phytic acid 3D network structure for superhydrophilic property of TiO2 nanoparticles

Traditionally, nano-TiO2 as one of the hydrophilic materials has garnered significant attention due to its inherent stability, non-toxicity, and abundance. However, its limited number of hydroxyl groups fails to meet the actual needs for superhydrophilic applications. Therefore, it is crucial to explore a simple and efficient method to introduce more hydroxyl groups to enhance the hydrophilicity of nano-TiO2. In this work, hydroxyl‑rich phytic acid (Pa) was introduced into the surface of nano-TiO2 and a 3D network structure of Co-coordinated phytic acid was further constructed to extremely enhance the hydrophilicity and stability of nano-TiO2. The TiO2@Pa-Co suspension was prepared by adsorbing hydroxyl‑rich Pa molecules on the surface of nano-TiO2 and assembling Co-coordinated Pa and then modified onto a glass slide by a conventional spin-coating method to obtain TiO2@Pa-Co thin film. The hydrophilic performance tests demonstrated that the TiO2@Pa-Co thin film presented innate superhydrophilic properties, as evidenced by a water contact angle of 2.0°, significantly smaller than that of the blank TiO2 (65.0°) and TiO2@Pa (29.1°) thin films. Notably, it also displays good durability, corrosion resistance, and anti-fogging properties. The superhydrophilic performances can be attributed to the ability of phytic acid to offer a large number of hydroxyl groups for improving the hydrophilicity of TiO2, while the Co ions act as a bridge, connecting with Pa and further construct a 3D network structure for the enhanced hydrophilic stability of TiO2. This study presents an inventive design concept to prepare superhydrophilic and stable TiO2 thin film by developing an organo-metallic coordination layer.

An Ice‐Dissolving‐Crosslinking Method for Efficient and Large‐Scale Preparation of Polyelectrolyte Monoliths with Ultra‐Stability in Aqueous Environments

AbstractIce‐templating is a versatile method for constructing macro‐porous hydrophilic polymer materials. However, the ice‐templating method is generally limited by high energy cost and low efficiency for large‐scale fabrication. Further, due to its hydrophilic nature, the constructed materials are vulnerable to water swelling and have poor structural stability. Here, an Ice‐Dissolving‐Crosslinking (IDCr) method is developed for efficient and large‐scale preparation of polyelectrolyte monoliths with ultra‐stability in aqueous environment. Specifically, Ice‐Dissolving in water‐miscible organic solvent is responsible for pore creation, while subsequent Crosslinking ensures pore structures stabilization. The macro‐porous architecture of materials, taking sodium carboxymethyl cellulose (CMC) as a polyelectrolyte example and trimesoyl chloride (TMC) as the crosslinker, CMC‐TMCIDCr is made much stabler as compared with the case of conventional Lyophilization‐Crosslinking technique (CMC‐TMCLC). The IDCr method is applicable to various hydrophilic polyelectrolytes and hybrids for long‐time use in water and brines, as exemplified by CMC‐TMC‐carbon nanotubes monolith, which exhibits high performance in solar thermal desalination process. This novel approach opens up new opportunities for the construction of porous monoliths with efficient preparation and excellent water stability.

Зависимость частоты спонтанной люксации комплекса капсульный мешок-ИОЛ от материала и массы линзы

Abstract Spontaneous luxation frequency dependence of the «capsule bag-IOL» complex on the material and weight of the lens A.A. Ivanov , O.P. Mishchenko , T.N. Iureva S. Fyodorov Eye Microsurgery Federal State Institution, Irkutsk Branch, Irkutsk, Russian Federation Irkutsk State Medical Academy of Postgraduate Education – branch of the FSBEI APE RMACPE, Irkutsk, Russian Federation Irkutsk State Medical University, Irkutsk, Russian Federation Relevance.Spontaneous luxation of the «capsule bag – IOL» complex in the long-term postoperative period is a serious complication. The search for regulated risk factors, the limitation of which will reduce the frequency of this complication, is relevant. Purpose. To evaluate association between frequency of spontaneous luxation of the «capsule bag – IOL» complex and the number of surgeries, taking into account the characteristics of the lens. Material and methods. 69 IOLs from 14 medical companies and 2 capsule rings were examined. The weight was determined using trusted torsion scales (accuracy ± 1 mg) under hydration conditions. IOLs were divided into 3 groups: ≤18 D; 18.5–24.0 D; ≥24.5 D. A retrospective analysis of 159 cases of spontaneous IOL luxation into the vitreous body over 13 years (2007–2020) was carried out. Comparison of IOL implantation results/luxation was carried out from 2006 to 2010, taking into account luxations from 2007 to 2020. Additionally, the number of years from IOL implantation to spontaneous luxation, the axial length of the eye, and the presence of pseudoexfoliation syndrome were evaluated. Results. A multiple excess of the weight of hydrophilic compared with hydrophobic IOLs was found in three comparison groups with a comparable refractive power (p=0.0001). Hydrophilic lenses in various groups were 1.5–1.82 times heavier than hydrophobic lenses. Spontaneous luxation of hydrophobic IOLs occurred less frequently by 11.86–49.22% compared to lenses made of hydrophilic materials. Conclusion.The weight of the IOL may play an important role in the pathogenesis of dislocation of the artificial lens. In the future, it is possible to develop recommendations to reduce the risk of luxation of the «capsule bag – IOL» complex in the long term for patients with an initial combination of non-correctable risk factors complicating the condition of the ligamentous apparatus of the lens. Key words: IOL luxation, IOL weight, lens material, hydrophilic or hydrophobic IOLs

Zwitterionic sulfobetaine-based hypercrosslinked hydrophilic materials for bioanalysis

Analysis of bioactive polar molecules is crucial for different fields, including biology, clinic medicine, and separation science. However, the design of the separation materials remains a huge challenge due to their tedious preparation process and limited chromatographic performances of traditional hydrophilic materials. New-generation hydrophilic polymer materials prepared via a sole-monomer system exhibit excellent reproducibility and chromatographic efficiency; however, such polymers reported to date have a high swelling propensity and risk of low surface exposure of functional groups, which limit their application as separation materials. In this study, N,N-bis(methacryloxyethyl)-N-methyl-N-(3-sulfopropyl)ammonium betaines (BMMSB), a zwitterionic sulfobetaine, was used to rapidly fabricate the zwitterionic hypercrosslinked hydrophilic polymer materials via the sole-monomer system. The novel hypercrosslinked hydrophilic materials exhibited high porosity and permeability, superhydrophilicity, low protein adsorption, and excellent capillary column efficiency (up to 134,950 plates/m for thiourea). It was able to enrich 28 N-glycopeptides from hIgG tryptic digests with a higher efficiency than that of traditional poly(SPE-co-EDMA) monolith and commercial ZIC-HILIC materials. Additionally, the polyBMMSB hydrophilic materials demonstrated superior selectivity and column efficiency to the poly(SPE-co-EDMA) monolith for the separation of various small bioactive molecules, including nucleobases and nucleosides, phenol derivatives, benzoic acid derivatives, urea and allantoin. Especially, high performance bioanalysis of Alzheimer’s disease biomarkers plasma Aβ42 and Aβ40, or some steroid hormones in human plasma were also achieved by the polyBMMSB monolith combined with nano liquid chromatography-mass spectrometry. As such, these sulfobetaine-based zwitterionic polymers may serve as a prototypical next-generation zwitterionic hydrophilic materials for rapid and efficient bioanalysis.

Fabrication of atelocollagen-coated bioabsorbable suture and the evaluation of its regenerative efficacy in Achilles tendon healing using a rat experimental model

Recently, the incidence of Achilles tendon ruptures (ATRs) has become more common, and repair surgery using a bioabsorbable suture is generally preferred, particularly in the case of healthy patients. Sutures composed of poly(lactic-co-glycolic acid) (PLGA) are commonly used in ATR surgeries. Nevertheless, owing to the inherent limitations of PLGA, novel bioabsorbable sutures that can accelerate Achilles tendon healing are sought. Recently, several studies have demonstrated the beneficial effects of atelocollagen on tendon healing. In this study, poly(3,4-dihydroxy-L-phenylalanine) (pDOPA), a hydrophilic biomimetic material, was used to modify the hydrophobic surface of a PLGA suture (Vicryl, VC) for the stable coating of atelocollagen on its surface. The main objective was to fabricate an atelocollagen-coated VC suture and evaluate its performance in the healing of Achilles tendon using a rat model of open repair for ATR. Structural analyses of the surface-modified suture indicated that the collagen was successfully coated on the VC/pDOPA suture. Postoperative in vivo biomechanical analysis, histological evaluation, ultrastructural/morphological analyses, and western blotting confirmed that the tendons in the VC/pDOPA/Col group exhibit superior healing than those in the VC and VC/pDOPA groups after 1 and 6 weeks following the surgery. The this study suggests that atelocollagen-coated PLGA/pDOPA sutures are preferable for future medical applications, especially in the repair of ATR.

Edible Long-Afterglow Photoluminescent Materials for Bioimaging.

Confining luminophores into modified hydrophilic matrices or polymers is a straightforward and widely used approach for afterglow bioimaging. However, the afterglow quantum yield and lifetime of the related material remain unsatisfactory, severely limiting the using effect especially for deep-tissue time-resolved imaging. This fact largely stems from the dilemma between material biocompatibility and the quenching effect of water environment. Herein an in situ metathesis promoted doping strategy is presented, namely, mixing ≈10-3 weight ratio of organic-emitter multicarboxylates with inorganic salt reactants, followed by metathesis reactions to prepare a series of hydrophilic but water-insoluble organic-inorganic doping afterglow materials. This strategy leads to the formation of edible long-afterglow photoluminescent materials with superior biocompatibility and excellent bioimaging effect. The phosphorescence quantum yield of the materials can reach dozens of percent (the highest case: 66.24%), together with the photoluminescent lifetime lasting for coupes of seconds. Specifically, a long-afterglow barium meal formed by coronene salt emitter and BaSO4 matrix is applied into animal experiments by gavage, and bright stomach afterglow imaging is observed by instruments or mobile phone after ceasing the photoexcitation with deep tissue penetration. This strategy allows a flexible dosage of the materials during bioimaging, facilitating the development of real-time probing and theranostic technology.

Cytocompatible hydrogel derived from dextrin and Poly(N-Vinyl acetamide) toward controlled antimicrobial release

The work aims to develop a biopolymer-dextrin-based three-dimensional crosslinked hydrophilic material for antimicrobial delivery. The copolymer (Dxt-PNVA) has been prepared by in-situ grafting of poly(N-vinylacetamide), followed by cross-linking with N,N'-methylenebisacrylamide with dextrin. By varying the concentrations of the reactants, an optimized copolymer (Dxt-PNVA 5) with the lowest % of crosslinking has been chosen for biomedical applications. The copolymeric gel has been characterized in detail using various techniques, followed by its cytocompatibility study using HeLa Cell lines that confirm the cytocompatible nature of the material. Copolymeric gel is a suitable material for the effective release of two antimicrobials (amoxicillin trihydrate and ornidazole) from tablet formulation for a prolonged period of 24 h. The obtained data demonstrates that the cytocompatible hydrogel has the potential characteristics of a daily dose administration for amoxicillin trihydrate and ornidazole.

Enhancing stability and immobilization techniques for graphitic carbon nitride in photocatalytic applications

Emerging contaminants from urban and industrial sources require effective water treatment and photocatalysis using graphitic carbon nitride (GCN) is emerging as a promising solution. This graphitic polymer, devoid of metals in its structure, exhibits properties similar to titanium oxide, the quintessential traditional photocatalyst. This work aims to optimize the application of GCN as photocatalysts, emphasizing its role in photocatalytic processes by improving its properties for the visible light-assisted photodegradation process and assessing the removal of a selected pollutant, Rhodamine B. Initially, the role of the catalyst precursor (urea, melamine and a ratio 1:1 of them) in the synthesis was evaluated. GCN obtained from urea as precursor yielded to better properties and higher purity of the catalyst. In addition, through acid treatment, slight improvements in the material properties were verified, such as an increase of the crystallinity and active sites. This acid modified catalyst enhanced the photocatalytic process, achieving complete removal of Rhodamine B in 30 min. A significant improvement in the chemical stability of the material was also observed, maintaining nearly its entire removal efficacy after 10 cycles. However, several operational problems were observed due to the powder form of the GCN, and, thus, requesting the development of efficient immobilized catalysts. Therefore, three techniques (encapsulation, electrospinning, and composite) were evaluated and the variations in GCN distribution and their influence on the photocatalysis process ascertained. From this evaluation, it can be concluded that the electrospinning technique, using polyacrylonitrile polymer (PAN) to form fibres, generated a highly porous, hydrophilic material with excellent floatability. This allowed maximizing radiation exposure during the process, achieving an 85 % reduction of Rhodamine B concentration in 90 min. Among other remarkable properties, GCN exhibits high reusability when incorporated into PAN fibres, as it remained chemically and physically stable, retaining more than 85 % of its dye removal efficiency after 4 cycles.

A Novel 3D High Resolution Imaging Method Using Correlative X-Ray and Electron Microscopy to Study Neodymium-Doped Yttrium Aluminum Garnet Laser-Induced Defects in Intraocular Lenses.

Cataract extraction is the most frequently performed ophthalmological procedure worldwide. Posterior capsule opacification remains the most common consequence after cataract surgery and can lead to deterioration of the visual performance with cloudy, blurred vision and halo, glare effects. Neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy is the gold standard treatment and a very effective, safe and fast procedure in removing the cloudy posterior capsule. Damaging the intraocular lens (IOL) during the treatment may occur due to wrong focus of the laser beam. These YAG-pits may lead to a permanent impairment of the visual quality. In an experimental study, we intentionally induced YAG pits in hydrophilic and hydrophobic acrylic IOLs using a photodisruption laser with 2.6 mJ. This experimental study established a novel 3D imaging method using correlative X-ray and scanning electron microscopy (SEM) to characterize these damages. By integrating the information obtained from both X-ray microscopy and SEM, a comprehensive picture of the materials structure and performance could be established. It could be revealed that although the exact same energies were used to all samples, the observed defects in the tested lenses showed severe differences in shape and depth. While YAG pits in hydrophilic samples range from 100 to 180 µm depth with a round shape tip, very sharp tipped defects up to 250 µm in depth were found in hydrophobic samples. In all samples, particles/fragments of the IOL material were found on the surface that were blasted out as a result of the laser shelling. Defects in hydrophilic and hydrophobic acrylic materials differ. Material particles can detach from the IOL and were found on the surface of the samples. The results of the laboratory study illustrate the importance of a precise and careful approach to Nd:YAG capsulotomy in order to avoid permanent damage to the IOL. The use of an appropriate contact glass and posterior offset setting to increase safety should be carried out routinely.