Hydrophobic Part Research Articles

Synergistic effect of lecithin and alginate, CMC, or PVP in stabilizing curcumin and its potential mechanism

This work aims to advance the understanding of the synergistic mechanism of lecithin and polymers (alginate, CMC, and PVP) in stabilizing curcumin, with a major focus on understanding the nanocomplex formation process and the main binding energy between molecules. It is demonstrated that lecithin and polymers have a synergistic effect in increasing the thermal acid, light, and digestion stability of curcumin. The potential mechanism is that the hydrophobic parts of curcumin molecules are first anchored at the region of the hydrophobic cavity of lecithin by van der Waals, while the hydrophilic parts are outward and are further encapsulated by hydrophilic polymers by van der Waals and electrostatic interaction to form a protective shell. This study contributes to our understanding of the synergistic mechanism of lecithin, polymers, and hydrophobic compounds, which can promote the synergistic use of lecithin and polymers to prepare nanocomplexes as an important tool for delivering bioactive compounds.

Development and photo-properties and intracellular behavior of visible-light-responsive molecule localizing to organelles of living cell

Visible-light-responsive azobenzene derivative in which a functional group having cell membrane permeability and a fluorophore were bonded was synthesized. This compound localized to the hydrophobic part in the lipid membrane of the liposome, and when the light corresponding to the transition absorption of azobenzene was irradiated, morphological change of the liposome was observed. When this compound was loaded into living cells, this molecule localized to the lysosome and when irradiated with light of the same wavelength caused cell death. These observed changes are thought to be due to photoisomerization of azobenzene derivatives.Graphical abstract

General adsorption isotherm for polyoxyethylene alkyl ethers CnEOm adsorbed at the water/air surface

An empirical adsorption isotherm model is presented based on fundamental thermodynamic equations of adsorption for the homologous series of the nonionic surfactants polyoxyethylene alkyl ethers (CnEOm) at the aqueous solution surface to determine the surface tension and surface pressure isotherms, surface equation of state, and molar characteristics for the adsorbed surfactant molecules. The new model describes the surface properties of CnEOm much better than the original Langmuir adsorption model used as thermodynamic basis. The analysis of the results shows that the increase of the alkyl chain length n (hydrophobic part) leads to an increase in the adsorption activity, while the increase of hydrophilic head group given by the number of EO units m, leads to a better solubility in water, and hence, to a smaller adsorbed amount. The results also show that the ethylene oxide group mainly influences the molar surface area.

Vibrational Sum Frequency Generation Spectra of Water-Vapor Interfaces Covered by Alcohols: Effects of Surface Coverage and Coupling between Oscillators.

The present study deals with the effects of varying coverage of water surface by alcohols on the vibrational sum frequency generation (VSFG) spectrum of interfacial water. We have considered two different alcohols: Tertiary butyl alcohol (TBA) whose alkyl part is fully branched and stearyl alcohol (STA) which has a long linear alkyl chain with larger hydrophobic surface area than that of TBA. With increase of the alcohol concentration, the hydrogen bonded OH stretch region of the VSFG spectrum is found to change following a regular trend for the STA-water system, whereas non-monotonic variation of the VSFG spectrum is observed for the TBA-water system which can be correlated with the presence of very different interactions of TBA molecules at different concentrations. On increasing the concentration of TBA, the hydrophobic groups get more tilted towards the water phase and significant hydrophobic interactions are introduced at higher concentrations. Whereas, for STA, there is a gradual increase in the hydrophilic interaction. Because of stacking interactions between the long chain alkyl groups, the hydrophobic parts stay outward from the water phase at higher concentrations and a regular change in the VSFG spectrum is observed. We have also presented a computationally efficient scheme to calculate the VSFG spectrum of interfacial systems for coupled oscillators which is expected to be beneficial for the treatment of coupling where the interfacial system size is inherently large.

Fabrication and morphological effect of waxberry-like carbon for high-performance aqueous zinc-ion electrochemical storage

Promoting and enhancing the transport rate of multivalent electrolyte ions in the pores of electrode is central for constructing high-performance electrochemical devices. Herein, waxberry-like porous carbon with nanosheets packaged by spherical carbon particles is produced by adjusting separation of hydrophilic and hydrophobic parts of carbon source precursors. The carbon particles maintain their original morphology after KOH activation at high temperature, forming tunable pores (pore volume: 0.9386 cm3 g−1) on the surface of stacked nanosheet layers. Benefiting from the synergistic effect of structural features, an interfacial transport of aqueous zinc ions within the carbon electrodes is achieved, endowing the assembled zinc-ion hybrid supercapacitors (ZHSCs) with excellent energy storage performances, including high capacity (122.3 mAh g−1 at 0.1 A g−1), high energy density (97.78 Wh kg−1), large power density (8000 W kg−1), and cycling stability up to 10,000 cycles with capacity retention of 98%. Moreover, the ZHSCs show superior low-temperature performance and operability (78.27 mAh g−1 at −30 °C and three-time cycling stability between −20 and 20 °C without performance degradation). This work presents a new prospect on design and development of aqueous rechargeable zinc-ion energy storage devices that are available for a range of environmental conditions.

Features of disruption mutants of genes encoding for hydrophobin Vmh2 and Vmh3 in mycelial formation and resistance to environmental stress in Pleurotus ostreatus.

Hydrophobins, which are small-secreted proteins with both hydrophobic and hydrophilic parts, can self-assemble into an amphiphilic film at the air-water interface, helping the fungus to form aerial hyphae. In the agaricomycete Pleurotus ostreatus, more than 20 putative hydrophobin genes have been predicted. Of these, two hydrophobin genes, vmh2 and vmh3, are predominantly expressed in the vegetative mycelium. In this study, we focused on the functions of Vmh2 and Vmh3 in vegetative mycelia. Based on the observation of the mycelial cross-section by transmission electron microscopy and the disappearance time of water droplets on the mycelial surface, Vmh2 and Vmh3 were considered essential for the maintenance of the surface hydrophobicity of the mycelium. The Δvmh3 and Δvmh2Δvmh3 strains exhibited relatively slower aerial mycelia formation on a liquid medium, and no significant alteration was observed in Δvmh2 strains. Only the Δvmh3 and Δvmh2Δvmh3 strains grew slower than the wild-type strain under stress conditions involving SDS and H2O2 on agar plates. This study revealed possible distinct roles for these hydrophobins in stress resistance. These results suggest that Agaricomycetes, including P. ostreatus, have evolved to possess multiple different hydrophobins as a means of adapting to various environments.

High amount of lecithin facilitates oral delivery of a poorly soluble pyrazoloquinolinone ligand formulated in lipid nanoparticles: Physicochemical, structural and pharmacokinetic performances

Preclinical development of deuterated pyrazoloquinolinone ligands, promising drug candidates for various neuropsychiatric disorders, was hindered by unusually low solubility in water and oils. DK-I-60-3 (7-methoxy-d3-2-(4-methoxy-d3-phenyl)-2,5-dihydro-3Hpyrazolo[4,3-c]quinolin-3-one) is one of such pyrazoloquinolinones, and we recently reported about increased oral bioavailability of its nanocrystal formulation (NC). Lipid nanoparticles (LNP) with a high concentration of lecithin, which enhances loading capacity of the lipid matrix, may give rise to further improvement. After preformulation studies by differential scanning calorimetry and polarized light microscopy, LNP were prepared by the hot high pressure homogenization, and characterized in terms of particle size, morphology, and encapsulation efficacy. The layered structure visible on atomic force micrographs was confirmed by nuclear magnetic resonance. Obtained formulations were desirably stable, with small particle size (<100 nm), and high encapsulation efficacy (>99 %). Lecithin was partially fluid and most probably located in the outer shell of the particle, together with DK-I-60-3. While the hydrophobic part of polysorbate 80 was completely immobilized, its hydrophilic part was free in the aqueous phase. In oral neuropharmacokinetic study in rats, an around 1.5-fold increase of area under the curve with LNP compared to NC was noticed both in brain and plasma. In bioavailability study, F value of LNP (34.7 ± 12.4 %) was 1.4-fold higher than of NC (24.5 ± 7.8 %); however, this difference did not reach statistical significance. Therefore, employment of LNP platform in preclinical formulation of DK-I-60-3 imparted an incremental improvement of its physicochemical as well as pharmacokinetic behavior.

The Interaction of Anthracycline Based Quinone-Chelators with Model Lipid Membranes: 1H NMR and MD Study.

Anthracycline antibiotics, e.g., doxorubicin, daunomycin, and other anthraquinones, are an important family of antitumor agents widely used in chemotherapy, which is currently the principal method for treating many malignancies. Thus, development of improved antitumor drugs with enhanced efficacy remains a high priority. Interaction of anthraquinone-based anticancer drugs with cell membranes attracts significant attention due to its importance in the eventual overcoming of multidrug resistance (MDR). The use of drugs able to accumulate in the cell membrane is one of the possible ways of overcoming MDR. In the present work, the aspects of interaction of anthraquinone 2-phenyl-4-(butylamino)naphtho[2,3-h]quinoline-7,12-dione) (Q1) with a model membrane were studied by means of NMR and molecular dynamics simulations. A fundamental shortcoming of anthracycline antibiotics is their high cardiotoxicity caused by reactive oxygen species (ROS). The important feature of Q1 is its ability to chelate transition metal ions responsible for ROS generation in vivo. In the present study, we have shown that Q1 and its chelating complexes penetrated into the lipid membrane and were located in the hydrophobic part of the bilayer near the bilayer surface. The chelate complex formation of Q1 with metal ions increased its penetration ability. In addition, it was found that the interaction of Q1 with lipid molecules could influence lipid mobility in the bilayer. The obtained results have an impact on the understanding of molecular mechanisms of Q1 biological activity.

Transformable prodrug nanoplatform via tumor microenvironment modulation and immune checkpoint blockade potentiates immunogenic cell death mediated cancer immunotherapy.

Rationale: Chemoimmunotherapy is a promising approach in cancer immunotherapy. However, its therapeutic efficacy is restricted by high reactive oxygen species (ROS) levels, an abundance of cancer-associated fibroblasts (CAFs) in tumor microenvironment (TME) as well as immune checkpoints for escaping immunosurveillance. Methods: Herein, a new type of TME and reduction dual-responsive polymersomal prodrug (TRPP) nanoplatform was constructed when the D-peptide antagonist (DPPA-1) of programmed death ligand-1 was conjugated onto the surface, and talabostat mesylate (Tab, a fibroblast activation protein inhibitor) was encapsulated in the watery core (DPPA-TRPP/Tab). Doxorubicin (DOX) conjugation in the chain served as an immunogenic cell death (ICD) inducer and hydrophobic part. Results: DPPA-TRPP/Tab reassembled into a micellar structure in vivo with TME modulation by Tab, ROS consumption by 2, 2'-diselanediylbis(ethan-1-ol), immune checkpoint blockade by DPPA-1 and ICD generation by DOX. This resolved the dilemma between a hydrophilic Tab release in the TME for CAF inhibition and intracellular hydrophobic DOX release for ICD via re-assembly in weakly acidic TME with polymersome-micelle transformation. In vivo results indicated that DPPA-TRPP/Tab could improve tumor accumulation, suppress CAF formation, downregulate regulatory T cells and promote T lymphocyte infiltration. In mice, it gave a 60% complete tumor regression ratio and a long-term immune memory response. Conclusion: The study offers potential in tumor eradication via exploiting an "all-in-one" smart polymeric nanoplatform.

A cationic lipid with advanced membrane fusion performance for pDNA and mRNA delivery.

The success of mRNA vaccines for COVID-19 prevention raised global awareness of the importance of nucleic acid drugs. The approved systems for nucleic acid delivery were mainly formulations of different lipids, yielding lipid nanoparticles (LNPs) with complex internal structures. Due to the multiple components, the relationship between the structure of each component and the overall biological activity of LNPs is hard to study. However, ionizable lipids have been extensively explored. In contrast to former studies on the optimization of hydrophilic parts in single-component self-assemblies, we report in this study on structural alterations of the hydrophobic segment. We synthesize a library of amphiphilic cationic lipids by varying the lengths (C = 8-18), numbers (N = 2, 4), and unsaturation degrees (Ω = 0, 1) of hydrophobic tails. Notably, all self-assemblies with nucleic acid have significant differences in particle size, stability in serum, membrane fusion, and fluidity. Moreover, the novel mRNA/pDNA formulations are characterized by overall low cytotoxicity, efficient compaction, protection, and release of nucleic acids. We find that the length of hydrophobic tails dominates the formation and stability of the assembly. And at a certain length, the unsaturated hydrophobic tails enhance the membrane fusion and fluidity of assemblies and thus significantly affect the transgene expression, followed by the number of hydrophobic tails.

Surfactant incorporated preyssler polyoxoanion: a transition metal substituted Mo-PHP complex and its applications.

The complex was prepared with preyssler polyoxoanion and transition metal (Mo), a cationic surfactant as a connector. It has tuneable physical and chemical potential which has been exploited to study novel properties. A new technique of shock wave impulses is also used on the Mo-PHP complex. Extensive use of cationic surfactants could impact accumulation in the environment set off the surfacing of bacterial resistance. Due to the electrostatic binding to bacterial surface, the hydrophobic parts of cationic surfactants tend to penetrate bacterial cell walls and may cause membrane lysis and bacteria death. The surfactant-supported and direct release of metal ions from P5W29Mo against bacterial resistance has been explained schematically. The dielectric study helps to understand the dissociation of cations that generate polarons and the hopping mechanism with neighbouring vacant atomic sites. Structural analysis confirms the formation of cationic surfactant incorporated polyoxoanion (Mo-PHP). A hexagonal shape-like structure for the PHP complex has been observed. The Mo-incorporated PHP complex was characterized using UV-visible (UV), Fourier Transform-infrared (IR), Raman spectra, scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques.

Pro-inflammatory protein S100A9 alters membrane organization by dispersing ordered domains

Pro-inflammatory, calcium-binding protein S100A9 is localized in the cytoplasm of many cells and regulates several intracellular and extracellular processes. S100A9 is involved in neuroinflammation associated with the pathogenesis of Alzheimer's disease (AD). The number of studies on the impact of S100A9 in co-aggregation processes with amyloid-like proteins is increasing. However, there is still a lack of data on how this protein interacts with lipid membranes. We employed atomic force microscopy (AFM), dynamic light scattering (DLS), and fluorescence measurements (Laurdan and Thioflavin-T) to study the interaction between protein and the membrane surface. We used lipid vesicles in bulk and planar tethered lipid bilayers as biomimetic membrane models. We demonstrated that the protein accumulates on negatively charged lipid bilayers but with no further loss of the bilayer's integrity. The most important result is that the initial adsorption and accumulation of apo-form of S100A9 on the lipid membrane surface is lipid phase-sensitive. The breaking down of raft-like and disappearance of gel-like domains indicate that protein incorporates into the hydrophobic part of the lipid bilayer. We observed the most noticeable loss of integrity in lipid bilayers constructed from a lipid mixture (brain total lipid extract). Understanding the function and interactions of these proteins in cellular environments might expand the development of new diagnostic and therapeutic approaches for AD or other related diseases.

Spectrometric study on the hydrophobic hydration in the formation of Tween-60 micelles with curcumin

The hydrophobic hydration in the formation of Tween-60 micelles upon entrapping bioactive curcumin has been observed and studied. The atypically increased values of pyrene polarity index suggest that Tween-60/curcumin complexes with bigger bulk hydrophobic part have stronger hydrophobic hydration than curcumin alone. The low-field shifts of water proton by 1H NMR method can also confirm the formation of stronger hydrogen bond network of water molecules surrounding Tween-60/curcumin complexes. However, the hydrophobic aggregation of surfactant alkyl chains into Tween-60 premicelles and micelles may destroy the hydrophobic hydration of Tween-60/curcumin complexes, which is indicated by the decreasing change of pyrene polarity index with increasing Tween-60 concentration. The fluorescence anisotropy of curcumin is observed to have sharply decreased values for Tween-60/curcumin complexes, which correlates positively with the hydrogen bonding strength of water molecules around curcumin. The fluorescence anisotropy, fluorescence spectroscopy and stability of curcumin cooperatively suggest that there is gradually weakened contact of curcumin with water in the order of curcumin alone, Tween-60/curcumin complexes, curcumin with Tween-60 premicelles and micelles. This work demonstrates that the hydrophobic hydration plays an important role in the entrapment of curcumin from a polar medium of water to surfactant micelles.

Synthesis of Benzothiazole Linked Triazole Conjugates and Their Evaluation Against Cholinesterase Enzymes

AbstractIn this paper we report the synthesis, in‐silico and in‐vitro evaluations of a new series of benzothiazole linked triazole conjugates. The synthesized compounds have been evaluated as the inhibitor of cholinesterase enzymes using Ellman's method. The benzothiazole and triazole derivatives were synthesized separately and further combined through covalent amide bond linkage.The compounds showed good to excellent results towards butyryl cholinesterase (BuChE) inhibition. Docking studies revealed that the hydrophobic aromatic part of N‐benzothiazole binds to the PAS and the 1,2,4‐triazole residue binds to the CAS of BuChE. The in‐silico docking results for BuChE are consistent with the in‐vitro results. Also, the molecular dynamics simulation studies of the best docked molecule 8 a had shown similar binding stability as the reference drug donepezil. Good molecular interaction was also observed for acetylcholinesterase (AChE). The molecular modelling and evaluations against cholinesterase enzyme provided novel lead molecule which with further modifications in their structure have potential for the treatment of Alzheimer disease (AD) in future.

Water-soluble β-cyclodextrin based turn-on amplifying fluorescent probes for sensitive and selective detection of Hg2+/Hg+ ions

In this work, fluorescent β- cyclodextrin (β-CD) based probes containing naphthalimide group were synthesized to realize the specific recognition of Hg2+/Hg+ in aqueous system. Firstly, three small fluorescent molecules (N1, N2 and N3) with -NH2 groups were synthesized from 4-bromo-1, 8-naphthalene anhydride. Secondly, CHCCH2- group was introduced into β-CD by Williamson ether formation reaction. Finally, the target probes (β-CD-PI, β-CD-PY and β-CD-TP) were obtained by Amino-Yne click reaction. These probes can efficiently recognize Hg2+/Hg+. β-CD-PI emits bright yellow fluorescence after binding with Hg2+/Hg+, which is a turn-on fluorescent probe. When the Hg2+/Hg+ concentration exceeds 26 μM, the fluorescence intensity amplifies sharply (20 folds). The hydrophobic parts of the probes aggregated together to form a micelle-like structure due to complexation with Hg2+/Hg+, resulting in special micelle-sensitizing properties. Meanwhile, the HOMO-LUMO energy levels of the probes were calculated by cyclic voltammetry (CV). The probe is expected to be used for the detection of Hg2+/Hg+ in aqueous solutions without any organic solvents.

Impact of lighter alkanes on the formation and dissociation kinetics of methane hydrate in oil-in-water dispersions relevant for flow assurance

Various crude oil fractions (saturates, aromatics, resins, and asphaltene) affect the hydrate formation cumulatively during the multiphase phase flow in offshore flowlines. This study investigates the impact of chain length of saturated hydrocarbons (nC5, nC6, nC7, and nC10) on methane hydrate formation and dissociation kinetics in oil-in-water dispersions at 275.15 K and 8 MPa. Sodium dodecyl sulfate (SDS) has been added (at 0, 500, 1000, and 1500 ppm concentration) to mimic the natural surfactants in the crude oil. Methane hydrate formation kinetics without surfactant does not correlate well with methane solubility trend in liquid alkanes (this study) due to narrow methane solubility difference along with poorly dispersed oil droplets without surfactant and stochastic hydrate induction behaviour. Increased SDS concentration (up to ∼1000 ppm) enhances the hydrate formation during initial stages due to enhanced oil–water interface following a decrease for higher concentration (∼1500 ppm) due to possible disruptions in the structure of local water by the hydrophilic surfactant part. At fixed surfactant concentration (∼1000 ppm), the hydrate formation is enhanced with increasing carbon number (nC6 < nC7 < nC10) during initial stages (∼10 h) due to lower methane solubility (increased methane availability in water) along with synergistic mechanism of alkane and SDS surfactant, before achieving similar formation kinetics during later stages. During dissociation, the gas release has been observably delayed at higher concentrations (∼1500 ppm) compared to lower (∼1000 ppm and below), possibly due to hydrate crystals trapping by surfactant molecules and methane adsorption on the hydrophobic surfactant part. A faster gas release has also been observed for systems with higher alkane at fixed surfactant concentration, possibly aided by lower methane solubility upon gaining enough thermal energy.

Surfactants-surface active agents behind sustainable living

Abstract Surfactants are surface active agents. They are mainly chemicals, when added to water will reduce the surface tension of water and thus increases wettability on the given surface. Surfactants normally carry hydrophilic and hydrophobic ends among which hydrophilic end connects to water layer. The hydrophobic part connects between aqueous phase and the given hydrophobic surface through the hydrophobic end. However, these surfactants act as emulsifying agents or foaming agents. Further the chemistry behind the action of surfactants is introduced for the readers. Surfactants can be classified based on origin, charge on heads, solubility of water etc. and is specified in this paper. Also synthesis of various types of surfactants is carefully incorporated in the chapter. The chapters dwells in detail the various sustainability related applications of surfactants which is relevant for sustainable living in the society.

Preparation and Properties of Different Polyether-Type Defoamers for Concrete.

In this study, a series of polyether-type defoamers for concrete which consist of the same alkyl chain (hydrophobic part) but different polyether chains (hydrophilic part) was prepared, and the structure-property relationship of the defoamers was investigated for the first time. Using oleyl alcohol (OA) as the starting agent (alkyl chain), the polyether defoamers with different polyether chains were prepared by changing the amount and sequence of ethylene oxide (EO) and propylene oxide (PO) units. The properties of different defoamers were tested in aqueous solutions, and fresh and hardened mortars; the structure-property relationship of the defoamers was thus studied. The results indicated that the defoaming capacity of the polyether defoamers decreased with an increased EO amount, and the defoamers linked with both EO and PO units (PO before EO) had a stronger defoaming capacity than those linked with EO only. This study is beneficial for the development and applications of novel synthetic polyether-type defoamers for concrete.

Self-assembly and complex formation of amphiphilic star and bottle-brush block copolymers.

We use molecular dynamics computer simulations to investigate complexation and clustering of branched polymers. In this study, we focus on star and bottle-brush polymers. In our investigation, we identify key factors governing cluster formation of branched amphiphilic polymers and provide guidance for designing and preparing various types of polymer clusters for applications, e.g., in drug delivery or materials science. We observe different kinds of clustering in the polymer systems. Our star polymers consist of several arms of hydrophilic core particles with hydrophobic particles attached to the end of each star arm. We observe that amphiphilic star polymers generally tend to form spherical complexes. In contrast to this, bottle-brush polymers exhibit a larger variety of complex structures. With large grafting density and large side arms, we also observe spherical polymer clusters; however, for low grafting density and shorter side chains, distinct clusters connected by bridging particles are formed. Furthermore, we observe membrane-like clustering of bottle-brush polymers. We employ two different clustering algorithms for further analysis of the obtained structures with respect to shape factors, pair correlation functions, and radii of gyration. We find that the hydrophobic parts of polymers play a crucial role in the formation of the resulting structures during self-assembly. The hydrophilic core parts in star polymers along with steric hindrance lead to a screening effect for the hydrophobic parts of the polymers. With bottle-brush copolymers, the hydrophilic parts of the polymers exhibit a screening effect that is sensitive to the grafting density and side chain lengths along the backbone.

Adsorption of extended anionic surfactants at the water- polymethylmethacrylate interface: The effect of polyoxyethylene groups

Wetting of solid surfaces is a typical phenomenon in daily life and manufacturing. The wettability of solid surfaces can be efficiently altered by certain surfactants. Extended surfactants, a novel class of surfactant with a unique structure, have a potent potential to convert neutral surfaces into hydrophilic surfaces. To deeply understand the influence of EO groups on the adsorption mechanism of surfactants at solid surfaces, the wettability of the extended anionic surfactants sodium cetyl (oxyethylene)3 carboxylate (C16EO3C), sodium cetyl (oxyethylene)5 carboxylate (C16EO5C), and sodium cetyl (oxyethylene)7 carboxylate (C16EO7C) on polymethylmethacrylate (PMMA) surfaces was investigated. Surface tension and contact angle experiments were used to determine adsorption characteristics such as adhesion tension, PMMA-liquid interface tension, and adhesion work. The experimental results show that the adsorption amounts of C16EOnC at the liquid-air interface are obviously larger than those at the PMMA-liquid interface. Below CMC, all three extended surfactant molecules adsorb at the PMMA-liquid interface via polar interactions and hydrophobic part towards the aqueous phase, which results in an increase of γSL. However, the decrease of γLV and the increase of γSL have opposite effects on the contact angle, resulting in almost constant values below CMC. With an increase in EO number, the hydrophobic modification ability increases because longer EO chains provide stronger polar interactions between C16EOnC molecules and the PMMA surface. Above CMC, C16EOnC molecules continue to adsorb at the PMMA-liquid interface and form a bilayer film. Conclusively, the contact angle abruptly decreased due to the hydrophilic modification of the PMMA surface. With an increase of EO number, the hydrophilic modification ability increases because surfactants with a larger EO number endow the second layer with a more hydrophilic nature.