Weak Hydrophobicity Research Articles

Synthesis and preparation of nanoparticles composed of amphiphilic poly(γ-glutamic acid) with different hydrophobic side chains and their potential of membrane disruptive activity

In the development of nanoparticle-based vaccine adjuvants, the interaction between nanoparticles (NPs) and the cells is a key factor. To control them, we focused on the relationship between the hydrophobicity of the side chains and the cell membrane. In this study, amphiphilic poly(γ-glutamic acid) (γ-PGA), using various types of hydrophobic side chains, was synthesized and used to prepare NPs for evaluating the membrane disruptive activity. When leucine ethyl ester (Leu), methionine ethyl ester (Met), or tryptophan ethyl ester (Trp) was grafted, each polymer formed monodispersed NPs at physiological conditions. Significantly, NPs composed of Leu and Trp showed a membrane disruptive activity at the endosomal environment (pH 5–6.5), while NPs composed of Met did not show. This might be due to the weak hydrophobicity of Met compared to that of Leu and Trp, which demonstrated that the interaction between NPs and cells could be controlled by designing the polymer compositions.

Molecular dynamics simulation and analysis of interfacial water at selected sulfide mineral surfaces under anaerobic conditions

In this paper, we report on a molecular dynamics simulation (MDS) study of the behavior of interfacial water at selected sulfide mineral surfaces under anaerobic conditions. The study revealed the interfacial water structure and wetting characteristics of the pyrite (100) surface, galena (100) surface, chalcopyrite (012) surface, sphalerite (110) surface, and molybdenite surfaces (i.e. the face, armchair-edge, and zigzag-edge surfaces), including simulated contact angles, relative number density profiles, water dipole orientations, hydrogen-bonding, and residence times. Two MDS force fields for the metal and sulfur atoms in selected sulfide minerals were created using UFF with partial charge determined by charge equilibration and using UFF with partial charge determined by Mulliken population analysis. Simulation results for the structural and dynamic properties of interfacial water molecules indicate the natural hydrophobic character for the selected sulfide mineral surfaces under anaerobic conditions as well as the relatively weak hydrophobicity for the sphalerite (110) surface and the two molybdenite edge surfaces.

Characterization and Classification of Pseudo-Stationary Phases in Micellar Electrokinetic Chromatography Using Chemometric Methods

Two types of chemometric methods, principal component analysis (PCA) and cluster analysis, are employed to characterize and classify a total of 70 pseudostationary phases (54 distinct systems and 16 decoy systems) in micellar electrokinetic chromatography (MEKC). PCA excels at removing redundant information for micellar phase characterization and retaining principal determinants for phase classification. While PCA is useful in the characterization of micelle selectivities, it is ineffective in defining the grouping of micellar phases. Hierarchical clustering yields a complete dendrogram of cluster structures but provides only limited cluster characterizations. The combination of these two chemometric methods leads to a comprehensive interpretation of the micellar phase classification. Moreover, the k-means analysis can further discern subtle differences among those closely located micellar phases. All three chemometric methods result in similar classifications with respect to the similarities and differences of the 70 micelle systems investigated. These systems are categorized into 3 major clusters: fluoro-surfactants represent cluster I, identified as strong hydrogen bond donors and dipolar but weak hydrogen bond acceptors. Cluster II includes sulfonated acrylamide/acrylate copolymers and surfactants with trimethylammonium head groups, characterized by strong hydrophobicity (v) and weak hydrogen bond acidity (b). The last cluster consists of two subclusters: clusters III and IV. Cluster III includes siloxane-based polymeric micelles, exhibiting weak hydrophobicity and medium hydrogen bond acidity and basicity (a), and the cluster IV micellar systems are characterized by their strong hydrophobicity and medium hydrogen bond acidity and basicity but rather weak dipolarity. Cluster III differs from cluster IV by its slightly weaker hydrophobicity and hydrogen bond donating capability. The classification by chemometric methods is in good agreement with the classification by the micellar selectivity triangle (MST) ( Fu, C.; Khaledi, M. G. J. Chromatogr., A 2009 , 1216 , 1891 - 1900 ).

Catalytic performance of PdCl2/Cu-HMS: Influence of hydrophobicity and structure of molecular sieves

Surface hydrophobically modified PdCl2/Si-Cu-HMS-m materials were successfully synthesized via a simple silylation process using methyltrichlorosilane and phenyltrichlorosilane respectively. They were characterized by a series of techniques including FT-IR, powder XRD, nitrogen adsorption–desorption, and the contact angle measurement of the water droplet. It was demonstrated that the mesoporous structure of Cu-HMS was retained after modification and that hydrophobicity was enhanced. However, silylation agents had a significant influence on catalytic performance. The experimental results indicated that PdCl2/Si-Cu-HMS-CH3 showed a high catalytic activity for the gas phase oxidative carbonylation of ethanol to diethyl carbonate (DEC) and a small steric hindrance but a weak hydrophobicity in comparison with PdCl2/Si-Cu-HMS-Ben catalyst, demonstrating that catalytic performance was relative to both by-product water and structure of molecular sieves catalyst, but the latter was a main factor in the catalytic system. In addition, a probable mechanism has been proposed to explain this result that structure of molecular sieves was the main factor of influencing catalytic performance.

Isolation and Characterization of Potential Probiotic Bacteria from Rainbow Trout Oncorhynchus mykiss, (Walbaum) Rearing Units Against Bacterial Pathogens

Bacteria were studied for potential probiotic activity against vibriosis, yersiniosis and lactococcosis in rainbow trout. A total of 79 bacterial strains were isolated from rainbow trout rearing water, and screened for antagonistic activity against Vibrio anguillarum, Yersinia ruckeri and Lactococcus garvieae using a well-diffusion agar assay. Vibrio spp. showed inhibitory activity against V. anguilarum and L. garvieae, while Aeromonas spp. displayed antagonistic activity against L. garvieae. Antagonistic L. garvieae strains displayed inhibitory activity against all pathogens. Antagonistic strains were characterized for enzymatic activity (protease, lipase) and hydrophobicity. Vibrio sp. A12, and Aeromonas sp. A5, G1, were found to have enzymatic properties and hydrophobicity. L. garvieae strains showed weak hydrophobicity and did not display enzymatic activity. Phenotypic characteristics of antagonistic strains were determined by conventional API 20NE and API STREP rapid identification systems. Antagonistic L. garvieae strains were confirmed as L. garvieae by PCR using species-specific primers. Candidate probiotic strains were tested for pathogenicity in rainbow trout by intraperitoneal injection. Following a challenge, L. garvieae strains caused mortality and were eliminated from further study. As a result, Aeromonas spp. and Vibrio spp. were identified as probiotic candidates with the potential to control vibriosis and lactococcosis.

The universality of β-hairpin misfolding indicated by molecular dynamics simulations

Previous molecular dynamics simulations showed that besides the experimentally measured folded structures, several β-structured polypeptides could also have misfolded "out-of-register" structures. Through the enhanced sampling molecular dynamics simulations on a series of polypeptides using either implicit or explicit solvent model, the present study systematically investigated the universality of β-hairpin misfolding and its determinants. It was observed that the misfolding could take place for almost all polypeptides under study, especially in the presence of weak side chain hydrophobicity. Moreover, the observed misfolded structures for various polypeptides share the following common features: (1) the turn length in misfolded structure is one-residue shorter than that in folded structure; (2) the hydrophobic side chains on the two strands are pointed to the opposite directions instead of packing in the same direction to form hydrophobic core cluster in the folded structure; and (3) the misfolded structure is one-residue-shifted asymmetric β-hairpin structure. The detailed analysis suggested that the misfolding of β-hairpin is the result of the competition between the formation of the alterable turn configurations and the inter-strand hydrophobic interactions. These predictions are desired to be tested by experiments.

Nanobubble column flotation of fine coal particles and associated fundamentals

Froth flotation is a widely used, cost effective particle separation process. However, its high performance is limited to a narrow particle size range between approximately 50 to 600μm for coal and 10 to 100μm for minerals. Outside this range, the efficiency of froth flotation decreases significantly, especially for difficult-to-float particles of weak hydrophobicity (e.g., oxidized coal).This study was aimed at enhancing recovery of an Illinois fine coal sample using a specially designed flotation column featuring a hydrodynamic cavitation nanobubble generator. Nanobubbles that are mostly smaller than 1μm can be formed selectively on hydrophobic coal particles from dissolved air in coal slurry. Results indicate that the combustible recovery of a −150μm coal increased by 5–50% in the presence of nanobubbles, depending on process operating conditions. Nanobubbles also significantly improved process separation efficiency. Other major advantages of the nanobubble flotation process include lower frother dosage and air consumption since nanobubbles are produced from air naturally dissolved in water, thereby resulting in considerably lower operating costs.

Vesicle deposition on hydrophilic solid surfaces

Supported lipid bilayers (SLBs) are popular as model systems for cell membranes and are promising for future applications in diagnostic devices and biomimetics. However, the mechanism of SLB formation is not fully understood. In this study, the deposition process of a single small unilamellar vesicle on hydrophilic supports is explored by dissipative particle dynamics. Depending on the lipid tail hydrophobicity and vesicle size, there exist three distinctive pathways of vesicle deposition, involving non-disintegrated, partially disintegrated, and completely disintegrated vesicle. A morphological phase diagram is presented and it reveals that a vesicle with weak tail hydrophobicity and small size tends to be completely disintegrated upon deposition. In contrast, the adsorption of an intact vesicle is observed as it possesses strong tail hydrophobicity and large size. Moreover, our simulation results clearly indicate that the deposition process of a vesicle onto the solid surfaces can be adjusted by altering the vesicular membrane tension and the interaction strength between the lipid head and the solid support. Finally, the deposition process of multiple vesicles on the hydrophilic solid surface is also investigated. The result shows that the fusion of vesicles has a tendency to hinder the formation of a SLB.

Preparation and Characterization of a New Quercetin‐bonded Stationary Phase for High Performance Liquid Chromatography

AbstractA quercetin‐bonded silica gel stationary phase (QUSP) containing natural flavonoid ligand was first prepared viaγ‐glycidoxypropyltrimethoxysilane (KH‐560) as a coupling reagent for high‐performance liquid chromatography. Its chemical structure was characterized by Fourier infrared spectroscopy, elemental analysis, thermal thermogravimetry and13C cross polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR). The chromatographic property of QUSP was systematically evaluated by using neutral, basic and acidic aromatic compounds as probes. In order to clarify its retention mechanism, a comparative study of QUSP with conventional octadecylsilyl‐bonded stationary phase (ODS) was also carried out under the same conditions. The results showed that the new quercetin‐bonded phase exhibited an excellent reversed‐phase chromatographic property with relatively weak hydrophobicity. However, it has an advantage over ODS in the fast separation of polar aromatic compounds because the quercetin ligand could provide various sites besides hydrophobicity, such as hydrogen bonding, dipole‐dipole, π‐π staking and charge transfer interactions. QUSP was performed in the baseline separations of ionized polar basic or acidic compounds, including pyridines, anilines, pyrimidines, purines and phenols with symmetric peak shape in common mobile phases without buffer salt within relatively short time. The natural ligands from herbs are readily available and contain a variety of active sites, which facilitate the exploration of industrial chromatographic separation materials for green products.

Potential of mean force between a large solute and a biomolecular complex: A model analysis on protein flux through chaperonin system

Insertion of a large solute into an even larger vessel comprising biopolymers followed by release of the same solute from it is one of the important functions sustaining life. As a typical example, an unfolded protein is inserted into a chaperonin from bulk aqueous solution, a cochaperonin acting as a lid is attached to the chaperonin rim and the protein folds into its native structure within the closed cavity, the cochaperonin is detached after the folding is finished, and the folded protein is released back to the bulk solution. On the basis of the experimental observations manifesting that the basic aspects of the protein flux through the chaperonin system is independent of the chaperonin, cochaperonin, and protein species, we adopt a simple model system with which we can cover the whole cycle of the protein flux. We calculate the spatial distribution of the solvent-mediated potential of mean force (PMF) between a spherical solute and a cylindrical vessel or vessel/lid complex. The calculation is performed using the three-dimensional integral equation theory, and the PMF is decomposed into energetic and entropic components. We argue that an unfolded protein with a larger excluded volume (EV) and weak hydrophobicity is entropically inserted into the chaperonin cavity and constrained within a small space almost in its center. The switch from insertion to release is achieved by decreasing the EV and turning the protein surface hydrophilic in the folding process. For this release, in which the energetic component is a requisite, the feature that the chaperonin inner surface in the absence of the cochaperonin is not hydrophilic plays essential roles. On the other hand, the inner surface of the chaperonin/cochaperonin complex is hydrophilic, and the protein is energetically repelled from it: The protein remains constrained within the small space mentioned above without contacting the inner surface for correct folding. The structural and inner-surface properties of the chaperonin or complex are controlled by the adenosine triphosphate (ATP) binding to the chaperonin, hydrolysis of ATP into adenosine diphosphate (ADP) and Pi, and dissociation of ADP and Pi. The function of the chaperonin system is exhibited by synchronizing the chemical cycle of ATP hydrolysis with hydration properties of a protein in the water confined on the scale of a nanometer which are substantially different from those in the bulk water.

Effects of Monovalent Cations on the Competitive Adsorption of Perfluoroalkyl Acids by Kaolinite: Experimental Studies and Modeling

Our hypothesis that longer-chained perfluoroalkyl acids (PFAAs) outcompete shorter-chained PFAAs during adsorption was tested in this study, wherein the adsorption interactions of six frequently detected PFAAs with kaolinite clay were modeled and examined experimentally using various suspension compositions. Competitive adsorption of PFAAs on the kaolinite surface was observed for the first time, and longer-chained PFAAs outcompeted those with a shorter chain. The electrostatic repulsion between adsorbed PFAA molecules is a primary inhibitory factor in PFAA adsorption. An increase in aqueous sodium or hydrogen ion concentration weakened electrostatic repulsions and changed the adsorption free energy. Therefore, the adsorption of a shorter-chained PFAA with weaker hydrophobicity could occur at high sodium or hydrogen ion concentrations. The experimental and modeling data suggest that the adsorption of shorter-chained PFAAs (≤4 perfluorinated carbons) in freshwater with a typical ionic strength of 10(-2.5) is not thermodynamically favorable. Furthermore, by measuring the electrokinetic potential of kaolinite suspension in the presence of PFAAs, we found that the kaolinite surface became more negatively charged because of the adsorption of PFAAs. This observation indicates that the adsorbed PFAA molecules were within the electrical double layer of the kaolinite surface and that they contributed to the potential at the slipping plane. The possible alignments of adsorbed PFAA molecules on the kaolinite surface were then proposed.

Modulation of the thermodynamic stability of proteins by polyols: Significance of polyol hydrophobicity and impact on the chemical potential of water

The exact mechanism of the modulation of chemical potential of proteins by polyols is not yet well understood. Present study investigates the role of hydrophobicity of polyols, and their impact on water activity and/or surface tension, in determining their stabilization/destabilization potential. Results with ribose and methyl-glucose show that the enhanced stability of proteins is not mediated via the effect on interfacial tension, a hypothesis that has so far been restricted to glycerol. An exemplary correlation between thermodynamic stabilization (Δ G f-uf), and polyol osmolality, confirms/generalizes the prominent role of water activity in the observed stabilization effects. Results show that even seemingly hydrophilic sugars such as deoxy-ribose can interact favorably with proteins, suggesting that properties other than the presence of hydroxyl groups also contribute to the net effect of polyols. We demonstrate that the hydrophobicity index of polyols and the net stabilization effect afforded to proteins have an excellent inverse correlation. These studies show that the weak hydrophobicity of polyols is critical for promoting their interactions with proteins, weakening of the hydrophobic forces within the protein interior and counteracting the polyol induced-solvent mediated stabilization effect.

Atypical early-time infiltration into a structured soil near field capacity: The dynamic interplay between sorptivity, hydrophobicity, and air encapsulation

Accurate measurement of infiltration attributes for the soil's surface layer is critical for understanding the dynamics of soil water in response to rainfall or irrigation. This study used four large lysimeters to measure the early-time infiltration behaviour of a structured, well-drained, silt loam Dystric Cambisol. For each lysimeter there were four separate infiltration experiments, with a 480-mm-diameter tension infiltrometer used to supply infiltrating water under suctions of 0, 0.5, 1, and 1.5 kPa. We consistently observed a lack of clear sorptivity-driven infiltration behaviour for all lysimeters under all surface-imposed suctions. Having ruled out artefacts of the tension infiltrometer–lysimeter system, surface seal development, air confinement, and a limited ‘infiltration capacity’ of the soil's top 50 mm layer, we conclude that direct and indirect effects of weak hydrophobicity and air encapsulation are the most important controls. Hydrophobicity, which appears to restrict the first 5–10 mm of infiltration, occurs despite the soils being close to field capacity. During unsaturated infiltration some macropores are non-fillable to infiltrating water, and we suggest that these pores may also act to isolate parts of the pore network that could otherwise exhibit sorptivity, and thus restrict early-time infiltration. The interaction between hydrophobicity and the “non-fillable” pore network may be an important mechanism causing non-uniform infiltration through preferential flowpaths. This may enhance air encapsulation by effectively blocking the escape path for the displaced air from parts of the pore network, further restricting the expression of sorptivity. In this sense the early-time infiltration behaviour of this soil is seen to be governed by the dynamic interaction between sorptivity, hydrophobicity, the network of air-filled pores, preferential flow and air encapsulation.

Intracellular Sorting Signals for Sequential Trafficking of Human Cytomegalovirus UL37 Proteins to the Endoplasmic Reticulum and Mitochondria

Human cytomegalovirus UL37 antiapoptotic proteins, including the predominant UL37 exon 1 protein (pUL37x1), traffic sequentially from the endoplasmic reticulum (ER) through the mitochondrion-associated membrane compartment to the mitochondrial outer membrane (OMM), where they inactivate the proapoptotic activity of Bax. We found that widespread mitochondrial distribution occurs within 1 h of pUL37x1 synthesis. The pUL37x1 mitochondrial targeting signal (MTS) spans its first antiapoptotic domain (residues 5 to 34) and consists of a weak hydrophobicity leader (MTSalpha) and proximal downstream residues (MTSbeta). This MTS arrangement of a hydrophobic leader and downstream proximal basic residues is similar to that of the translocase of the OMM 20, Tom20. We examined whether the UL37 MTS functions analogously to Tom20 leader. Surprisingly, lowered hydropathy of the UL37x1 MTSalpha, predicted to block ER translocation, still allowed dual targeting of mutant to the ER and OMM. However, increased hydropathy of the MTS leader caused exclusion of the UL37x1 high-hydropathy mutant from mitochondrial import. Conversely, UL37 MTSalpha replacement with the Tom20 leader did not retarget pUL37x1 exclusively to the OMM; rather, the UL37x1-Tom20 chimera retained dual trafficking. Moreover, replacement of the UL37 MTSbeta basic residues did not reduce OMM import. Ablation of the MTSalpha posttranslational modification site or of the downstream MTS proline-rich domain (PRD) increased mitochondrial import. Our results suggest that pUL37x1 sequential ER to mitochondrial trafficking requires a weakly hydrophobic leader and is regulated by MTSbeta sequences. Thus, HCMV pUL37x1 uses a mitochondrial importation pathway that is genetically distinguishable from that of known OMM proteins.

Dissection of the Zipping-and-Assembly Mechanism for Folding of Model Proteins

Zipping-and-assembly mechanism (ZAM) is a new mechanism describing the kinetics of protein folding. To dissect the validity of this mechanism for various protein-like systems, a prediction test based on three-dimensional HP lattice models is carried out. It is found that only the native structures of a part of protein-like models could be predicted with a ZAM-based method. The detailed comparisons between the model proteins which are predicted or failed with the ZAM-based method suggest that the ZAM is likely to be applicable for the model proteins with the weak hydrophobicity, the low contact order for native conformations, and the large separation between the energies of native state and denatured states. These observations bring us more information about the protein-like systems for which the ZAM could be applied.

Dynamic control of protein conformation transition in chromatographic separation based on hydrophobic interactions: Molecular dynamics simulation

Conformational transitions of a protein in hydrophobic interaction based chromatography, including hydrophobic interaction chromatography (HIC) and reversed-phase liquid chromatography (RPLC), and their impact on the separation process and performance were probed by molecular dynamics simulation of a 46-bead β-barrel coarse-grained model protein in a confined pore, which represents the porous adsorbent. The transition of the adsorbed protein from the native conformation to an unfolded one occurred as a result of strong hydrophobic interactions with the pore surface, which reduced the formation of protein aggregates. The conformational transition was also displayed in the simulation once an elution buffer characterized by weaker hydrophobicity was introduced to strip protein from pore surface. The discharged proteins that underwent conformational transition were prone to aggregation; thus, an unsatisfactory yield of the native protein was obtained. An orthogonal experiment revealed that in addition to the strengths of the protein–protein and protein–adsorbent hydrophobic interactions, the elution time required to reduce the above-mentioned interactions also determined the yield of native protein by HIC and RPLC. Stepwise elution, characterized by sequential reduction of the hydrophobic interactions between the protein and adsorbent, was presented as a dynamic strategy for tuning conformational transitions to favor the native conformation and reduce the formation of protein aggregates during the elution process. The yield of the native protein obtained by this dynamic operation strategy was higher than that obtained by steady-state elution. The simulation study qualitatively reproduced the experimental observations and provided molecular insight that would be helpful for designing and optimizing HIC and RPLC separation of proteins.

Homopolymer induced phase evolution in mesoporous silica from evaporation induced self-assembly process

In this paper, we report the experimental findings on the phase evolution of mesoporous silica in an evaporation induced self-assembly (EISA) approach by using low molecular weight homopolymer poly(propylene oxide) ( M n = 400, PPO400) as an additive. It is found that the addition of PPO400 can cause hydrotropic curvature-reducing effect on the mesostructures. Upon the increase of PPO400 addition amount, the structures of the obtained mesoporous silicas gradually evolve from three-dimensional (3-D) cubic Im 3 ¯ m to quasi- p6m, to hexagonal p6m, and to mixed structures consisting of lamellar and reversed cylindrical structure. The quasi- p6m mesoporous silica structure has the buckled cylindrical mesopores with intermediate curvature and acts as the metastable structure during the phase evolution from Im 3 ¯ m to p6m structure. We ascribe this curvature-reducing effect to the relatively weak hydrophobicity and good compatibility of PPO400 homopolymer. Moreover, the condition with larger homopolymer PPO4000 ( M n = 4000) as the additive has been also investigated and discussed.

Vapor Phase Beckmann Rearrangement of Cyclohexanone Oxime Over Rare Earth Pyrophosphates

A new application of rare earth pyrophosphates in vapor phase Beckmann rearrangement of cyclohexanone oxime was investigated. The rare earth phosphates were characterized by means of XRD, FT-IR, NH3-TPD and water contact angle measurement. It was found that the weak surface acidity and appropriate surface hydrophobicity should be two key factors in the excellent performance of these catalysts.

Association behavior of one-end hydrophobically modified poly[N 5-(2-hydroxyethyl) l-glutamine] in water/ethylene glycol mixed solvent

Amphiphilic polymers Cn-PHEG consisting of water-soluble poly[N 5-2-(hydroxyethyl) l-glutamine] (PHEG) and hydrophobic alkyl chain (carbon number n = 12, 14, 16, or 18) attached at the PHEG terminal was prepared, and association behavior and structure of associate for Cn-PHEG in selective solvent (water/ethylene glycol mixed solvent) have been investigated. α-Helix content of PHEG block for all the polymers increased with weight fraction of ethylene glycol in the mixed solvent (W EG). By light scattering measurements, formation of a small micelle was suggested for C14-, C16-, and C18-PHEG when W EG = 0. With the increase in W EG, appearance of a larger associate was revealed for C16- and C18-PHEG. Evaluated molecular weight and radius of gyration suggested that the micelle is star-like sphere when W EG = 0 and worm-like cylinder when W EG = 0.7. C12-PHEG did not demonstrate any distinct micellization behavior because of the weak hydrophobicity of C12 chain.

Preparation and Evaluation of 3,5-Dinitrobenzoyl-Bonded Silica Gel Stationary Phase for HPLC

Column packing materials are always a key factor influencing the development of high-performance liquid chromatography (HPLC). In this paper, a new preparation method of 3,5-dinitrobenzoyl-bonded silica gel stationary phase (DNB) for HPLC was developed by using N-(β-aminoethyl)-γ-aminopropyl-methyldimethoxy silane as coupling reagent. Its structure was characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy, and thermal analysis. The surface concentration of 3,5-dinitrobenzoyl ligand is 2.082 μmol m−2, according to the carbon content of elemental analysis. The chromatographic performance of new packing was evaluated by using different solute probes, such as alkylbenzenes, polycyclic hydrocarbons (PAHs), phenols, naphthalene derivatives, nitrophenol positional isomers, and sulfonamides. The results show that DNB was of the reversed-phase packing kind with weak hydrophobicity and versatile chromatographic property compared with octadecyl silane. The charge transfer between the dinitrobenzoyl ligand and the analytes plays a significant role in the separation of phenols and naphthalene derivatives. In addition, electrostatic, hydrogen-bonding, and dipole-dipole interactions are responsible for the above separations, which improve the selectivity of DNB for solutes. An advantage of DNB is that it is suitable for the separation of the basic compounds containing nitrogen atoms without a capped process because the spacer containing nitrogen atoms can shield the residual silanols from DNB.