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1.
Proc Natl Acad Sci U S A ; 118(37)2021 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-34504006

RESUMO

The extracellular matrix (ECM) is mechanically inhomogeneous due to the presence of a wide spectrum of biomacromolecules and hierarchically assembled structures at the nanoscale. Mechanical inhomogeneity can be even more pronounced under pathological conditions due to injury, fibrogenesis, or tumorigenesis. Although considerable progress has been devoted to engineering synthetic hydrogels to mimic the ECM, the effect of the mechanical inhomogeneity of hydrogels has been widely overlooked. Here, we develop a method based on host-guest chemistry to control the homogeneity of maleimide-thiol cross-linked poly(ethylene glycol) hydrogels. We show that mechanical homogeneity plays an important role in controlling the differentiation or stemness maintenance of human embryonic stem cells. Inhomogeneous hydrogels disrupt actin assembly and lead to reduced YAP activation levels, while homogeneous hydrogels promote mechanotransduction. Thus, the method we developed to minimize the mechanical inhomogeneity of hydrogels may have broad applications in cell culture and tissue engineering.


Assuntos
Materiais Biocompatíveis/química , Diferenciação Celular , Linhagem da Célula , Células-Tronco Embrionárias Humanas/citologia , Hidrogéis/química , Mecanotransdução Celular , Osteoblastos/citologia , Células-Tronco Embrionárias Humanas/metabolismo , Humanos , Osteoblastos/metabolismo , Engenharia Tecidual
2.
Small ; 19(12): e2206461, 2023 03.
Artigo em Inglês | MEDLINE | ID: mdl-36587969

RESUMO

Structurally-colored photonic hydrogels which are fabricated by introducing hydrogels into thin films or photonic crystal structures are promising candidates for biosensing. Generally, the design of photonic hydrogel biosensors is based on the sensor-analyte interactions induced charge variation within the hydrogel matrix, or chemically grafting binding sites onto the polymer chains, to achieve significant volume change and color variation of the photonic hydrogel. However, relatively low anti-interference capability or complicated synthesis hinder the facile and low-cost fabrication of high-performance photonic hydrogel biosensors. Here, a facilely prepared supramolecular photonic hydrogel biosensor is developed for high-sensitivity detection of alkaline phosphatase (ALP), which is an extensively considered clinical biomarker for a variety of diseases. Responding to ALP results in the broken supramolecular crosslinking and thus increased lattice distancing of the photonic hydrogel driven by synergistic repulsive force between nanoparticles embedded in photonic crystal structure and osmotic swelling pressure. The biosensor shows sensitivity of 7.3 nm spectral shift per mU mL-1 ALP, with detection limit of 0.52 mU mL-1 . High-accuracy colorimetric detection can be realized via a smartphone, promoting point-of-care sensing and timely diagnosis of related pathological conditions.


Assuntos
Técnicas Biossensoriais , Hidrogéis , Hidrogéis/química , Fosfatase Alcalina , Polímeros/química , Pressão Osmótica , Técnicas Biossensoriais/métodos
3.
Anal Chem ; 94(27): 9497-9507, 2022 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-35759455

RESUMO

The sensitivity of colorimetric photonic crystal (PC) sensors have been significantly improved with the advancement of deformable structural color materials, structures design, sensing signal analysis methods, and fabrication strategies. In this perspective, the strategies toward high-sensitivity colorimetric PC sensors are discussed, from the perspectives of molecular design, single sensor construction, and multisensor assembly, which include incorporation of flexible polymer chains, construction of strong sensor-analyte interactions, incorporation of more soft materials, construction of stimuli-angle/orientation relationship, design of colorimetric sensors in series, and assembly of colorimetric PC sensors in parallel. Based on these strategies, progress of high-sensitivity colorimetric PC sensors in recent years is summarized, in terms of mechano-sensors and chemo-/biosensors. Specifically, PC based optical-electrical dual-signal sensing devices are included. Finally, the future development and challenges of high-sensitivity colorimetric PC sensors are presented, in regards to deformable properties, optical properties, analysis methods, and fabrication strategies.


Assuntos
Técnicas Biossensoriais , Colorimetria , Técnicas Biossensoriais/métodos , Fótons , Polímeros
4.
Plant Biotechnol J ; 17(1): 103-117, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-29754465

RESUMO

Lignified stone cells substantially reduce fruit quality. Therefore, it is desirable to inhibit stone cell development using genetic technologies. However, the molecular mechanisms regulating lignification are poorly understood in fruit stone cells. In this study, we have shown that microRNA (miR) miR397a regulates fruit cell lignification by inhibiting laccase (LAC) genes that encode key lignin biosynthesis enzymes. Transient overexpression of PbrmiR397a, which is the miR397a of Chinese pear (Pyrus bretschneideri), and simultaneous silencing of three LAC genes reduced the lignin content and stone cell number in pear fruit. A single nucleotide polymorphism (SNP) identified in the promoter of the PbrmiR397a gene was found to associate with low levels of fruit lignin, after analysis of the genome sequences of sixty pear varieties. This SNP created a TCA element that responded to salicylic acid to induce gene expression as confirmed using a cell-based assay system. Furthermore, stable overexpression of PbrmiR397a in transgenic tobacco plants reduced the expression of target LAC genes and decreased the content of lignin but did not change the ratio of syringyl- and guaiacyl-lignin monomers. Consistent with reduction in lignin content, the transgenic plants showed fewer numbers of vessel elements and thinner secondary walls in the remaining elements compared to wild-type control plants. This study has advanced our understanding of the regulation of lignin biosynthesis and provided useful molecular genetic information for improving pear fruit quality.


Assuntos
Frutas/crescimento & desenvolvimento , Lignina/metabolismo , MicroRNAs/fisiologia , Pyrus/crescimento & desenvolvimento , Frutas/metabolismo , Regulação da Expressão Gênica de Plantas , Genes de Plantas/genética , Genes de Plantas/fisiologia , Lignina/biossíntese , MicroRNAs/genética , Filogenia , Plantas Geneticamente Modificadas , Pyrus/genética , Pyrus/metabolismo , Análise de Sequência de DNA , Nicotiana/genética , Nicotiana/metabolismo
5.
Phys Biol ; 12(4): 045006, 2015 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-26118480

RESUMO

The single-molecule fluorescence technique is becoming a general and mature tool to probe interactions and dynamics of biomolecules with ultra high precision and accuracy. However, nonspecific adsorption of biomolecules to the flow cells remains a major experimental riddle for the study of many complex biological systems, especially those exhibiting low binding affinity and presenting with weakly populated intermediates. Many novel surface passivation methods have been introduced to reduce nonspecific interactions. Here, we present an effective and inexpensive method to significantly reduce nonspecific binding of biomolecules in conventional poly (ethylene glycol) (PEG)-based surface passivation protocols, without additional exogenous effects. In particular, we propose a simple 10 min Tween-20 treatment for the PEG passivated surface, which could further increase the hydrophilicity of the surface and thus promote passivation efficacy by about 5 to 10 times. We anticipate that this new procedure will find broad practical applications and extend the current reaches of single-molecule fluorescence studies.


Assuntos
Transferência Ressonante de Energia de Fluorescência , Nanotecnologia/métodos , Polietilenoglicóis/química , Adsorção , Interações Hidrofóbicas e Hidrofílicas , Polietilenoglicóis/metabolismo , Propriedades de Superfície
6.
Virol J ; 12: 92, 2015 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-26084565

RESUMO

BACKGROUND: Coxsackievirus A4 (CV-A4) is classified as human enterovirus A according to its serotype. CV-A4, an etiological agent of hand, foot, and mouth disease, affects children worldwide and can circulate in closed environments such as schools and hospitals for long periods. FINDINGS: An outbreak of febrile illness at a nursery school in Beijing, China, was confirmed to be caused by CV-A4. Phylogenetic analysis of the complete genome of the isolated strain showed that the virus belongs to the same cluster as the predominant CV-A4 strain in China. This outbreak was controlled by effective measures. CONCLUSIONS: The early identification of the pathogen and timely intervention may be the most critical factors in controlling an outbreak caused by CV-A4 in a preschool.


Assuntos
Infecções por Coxsackievirus/epidemiologia , Surtos de Doenças , Enterovirus/classificação , Enterovirus/isolamento & purificação , Febre/etiologia , Escolas Maternais , Pequim/epidemiologia , Criança , Pré-Escolar , Infecções por Coxsackievirus/patologia , Infecções por Coxsackievirus/virologia , Feminino , Febre/virologia , Humanos , Lactente , Controle de Infecções/métodos , Masculino , Dados de Sequência Molecular , RNA Viral/genética , Análise de Sequência de DNA
7.
Zhonghua Yi Xue Za Zhi ; 95(10): 761-5, 2015 Mar 17.
Artigo em Zh | MEDLINE | ID: mdl-26080849

RESUMO

OBJECTIVE: To evaluate the efficacies of a modified oral appliance (MOA) for residual obstruction after uvulopalatopharyngoplasty (UPPP) in the treatment of moderate-to-severe obstructive sleep apnea hypopnea syndrome (OSAHS). METHODS: The patients with residual airway obstruction on polysomnography (PSG) at four weeks post-UPPP were selected from the Sleep Medicine Center, Gansu Provincial People's Hospital from October 2013 to February 2014. As of week 5 post-UPPP, all subjects wore MOA for 4 weeks. Before and 4 weeks after treatment, questionnaires were distributed to evaluated the improvement of subjective and objective sleep. The average apnea hyponea index (AHI) and sleep patterns were examined by PSG. The sagittal diameter in minimal region of retropalatal and retroglossal patency and the volume of orophary were measured by cone beam computed tomography (CBCT) scans. And the correlation between the outcomes of CBCT and AHI were analyzed. RESULTS: A total of 10 male OSAHS patients were enrolled. The average age was (42.4 ± 9.2) (31-55) years, body mass index (BMI) (25.0 ± 4.8) (22.8-29.4) kg/m² and AHI was (26.0 ± 7.5) (15.8-35.9)/h. After wearing MOA for 4 weeks, the symptoms of snoring, daytime somnolence and suffocated waking during sleep improved as compared with that pre-treatment. All adapted to sleep with MOA. Average AHI decreased from (26.0 ± 7.5)/h to (6.0 ± 0.7)/h (P < 0.001). And the lowest average oxygen saturation value (SaO2) increased from (79.6 ± 3.9)% to (87.6 ± 1.6)% (P < 0.001). PSG indicated that the percentage of awakening time and sleep time in nonrapid eye movement (NREM) stage 1 decreased from (11.0 ± 2.3)% and (26.1 ± 4.3)% to (6.8 ± 1.6)% and (11.1 ± 1.5)% respectively in total sleep time (TST). The percentage of NREM stage3 sleep time and rapid eye movement (REM) sleep time in TST increased on average from (10.2 ± 2.2)% and (11.6 ± 1.4)% to (17.7 ± 3.1)% and (21.3 ± 3.1)% respectively (all P < 0.001). CBCT measurements showed that the sagittal diameter in minimal region of retropalatal and retroglossal patency increased on average by (0.64 ± 0.04) and (1.51 ± 0.18) mm respectively. The average volume of orophary increased by (2 446 ± 963) mm³ (all P < 0.05). Negative correlations existed between AHI and sagittal diameter of minimal region of retroglossal patency, AHI and volume of orophary (all P < 0.05). CONCLUSION: The application of MOA after UPPP can significantly increase the sagittal diameter of minimal region of retroglossal patency and the volume of orophary and improve effectively hyperpnoea and disordered sleep patterns.


Assuntos
Apneia Obstrutiva do Sono , Úvula , Adulto , Índice de Massa Corporal , Tomografia Computadorizada de Feixe Cônico , Humanos , Masculino , Pessoa de Meia-Idade , Palato , Faringe , Polissonografia , Fases do Sono , Ronco , Inquéritos e Questionários
8.
Nanotechnology ; 25(29): 295103, 2014 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-24990410

RESUMO

Probe bismuth sulfide modified with Pluronic F127 (Bi2S3-PF127), which has high biocompatibility and dispersibility, is synthesized using triblock copolymer Pluronic F127 to modify hydrophobic Bi2S3 nanoparticles that are prepared by a hot injection method. TEM results show that most of the probe has a length of about 14.85 ± 1.70 nm and a breadth of about 4.79 ± 0.63 nm. After injected into the tail vein of a mouse, the probe has obvious CT contrast enhancement capability from x-ray CT imaging results. Meanwhile, the probe's in vivo toxicity is also studied. It is found that hematoxylin and eosin stains of major organs have no change. A biochemical analysis (alanine aminotransferase and aspartate aminotransferase) prove the probe has no adverse effects. The results of a blood analysis (white blood cell count, red blood cell count, hemoglobin, and platelet count) are also normal. The biological distribution of Bi by ICP-AES shows that most of nanoparticles are cleaned out after injection 48 h, and the circulation half-life of the probe is 5.0 h, suggesting that Bi2S3-PF127 has a long circulation and indicating that the Bi2S3-PF127 probe has good biocompatibility and safety.


Assuntos
Materiais Biocompatíveis/síntese química , Meios de Contraste/síntese química , Nanopartículas/química , Tomografia Computadorizada por Raios X/métodos , Animais , Materiais Biocompatíveis/efeitos adversos , Bismuto/química , Sobrevivência Celular/efeitos dos fármacos , Meios de Contraste/efeitos adversos , Camundongos , Camundongos Endogâmicos BALB C , Nanopartículas/efeitos adversos , Poloxâmero/química , Sulfetos/química
9.
Mater Horiz ; 11(2): 519-530, 2024 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-37982193

RESUMO

Oral pathogens can produce volatile sulfur compounds (VSCs), which is the main reason for halitosis and indicates the risk of periodontitis. High-sensitivity detection of exhaled VSCs is urgently desired for promoting the point-of-care testing (POCT) of halitosis and screening of periodontitis. However, current detection methods often require bulky and costly instruments, as well as professional training, making them impractical for widespread detection. Here, a structural color hydrogel for naked-eye detection of exhaled VSCs is presented. VSCs can reduce disulfide bonds within the network, leading to expansion of the hydrogel and thus change of the structural color. A linear detection range of 0-1 ppm with a detection limit of 61 ppb can be achieved, covering the typical VSC concentration in the breath of patients with periodontitis. Furthermore, visual and in situ monitoring of Porphyromonas gingivalis responsible for periodontitis can be realized. By integrating the hydrogels into a sensor array, the oral health conditions of patients with halitosis can be evaluated and distinguished, offering risk assessment of periodontitis. Combined with a smartphone capable of color analysis, POCT of VSCs can be achieved, providing an approach for the monitoring of halitosis and screening of periodontitis.


Assuntos
Halitose , Periodontite , Humanos , Halitose/diagnóstico , Halitose/prevenção & controle , Hidrogéis , Periodontite/diagnóstico , Porphyromonas gingivalis , Compostos de Enxofre/análise
10.
Langmuir ; 29(43): 13299-306, 2013 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-24090141

RESUMO

Peptide-based supramolecular hydrogels have been extensively explored in biomaterials owing to their unique bioactive, stimulus-responsive, and biocompatible features. However, peptide-based hydrogels often have low mechanical stability with storage moduli of 10-1000 Pa. They are susceptible to mechanical destruction and solvent erosion, greatly hindering their practical application. Here, we present a photo-cross-linking strategy to enhance the mechanical stability of a peptide-based hydrogel by 10(4)-fold with a storage modulus of ~100 kPa, which is one of the highest reported so far for hydrogels made of small peptide molecules. This method is based on the ruthenium-complex-catalyzed conversion of tyrosine to dityrosine upon light irradiation. The reinforcement of the hydrogel through photo-cross-linking can be achieved within 2 min thanks to the fast reaction kinetics. The enhancement of the mechanical stability was due to the formation of a densely entangled fibrous network of peptide dimers through a dityrosine linkage. We showed that in order to implement this method successfully, the peptide sequence should be rationally designed to avoid the cross talk between self-assembly and cross-linking. This method is convenient and versatile for the enhancement of the mechanical stability of tyrosine-containing peptide-based hydrogels. We anticipate that the photo-cross-linked supramolecular hydrogels with much improved mechanical stability will find broad applications in tissue engineering and drug controlled release.


Assuntos
Reagentes de Ligações Cruzadas/química , Hidrogéis/química , Peptídeos/química , Engenharia de Proteínas , Tirosina/química , Materiais Biocompatíveis/síntese química , Materiais Biocompatíveis/química , Reagentes de Ligações Cruzadas/síntese química , Hidrogéis/síntese química , Estrutura Molecular , Tamanho da Partícula , Peptídeos/síntese química , Processos Fotoquímicos , Propriedades de Superfície
11.
Shanghai Kou Qiang Yi Xue ; 32(2): 209-213, 2023 Apr.
Artigo em Zh | MEDLINE | ID: mdl-37154006

RESUMO

PURPOSE: To compare the effects of three occlusal adjustment methods in different sequences by articulating paper on the delayed occlusal characteristics of single molars. METHODS: Thirty-two implants of first molars were divided into group A(n=12), group B (n=12) and group C (n=12) by sequential adjustment according to random number means, and (100+40), (100+50+30) and (100+40+20) µm sequence occlusal papers were used for occlusal adjustment, respectively. TeeTester was used to measure the delay time and force ratio between prosthesis and adjacent teeth at restoration day, 3 and 6 months after restoration, and to record the number of cases readjusting in each group during follow-up. SPSS 25.0 software package was used for data analysis. RESULTS: There were significant differences in delay time between groups at restoration day (P<0.05), and 3 and 6 months after restoration, delay time of group C was still smaller than that of group A and B (P<0.05). During follow-up, the time of each group showed a trend of shortening (P<0.05), but there was still delayed occlusion. Compared with group B and C, the force ratio in group A was lower at each time(P<0.05). The ratio of each group showed an increasing trend during follow-up (P<0.05), and group C showed the largest increase (P<0.001). The number of cases readjusting was relatively small in group A, and the most was in group C(P<0.05). There was positive correlation between delay time and force difference of prosthesis and adjacent teeth(P<0.001). CONCLUSIONS: The (100+40) µm sequence group had higher occlusal stability and better clinical applicability. The smaller the occlusal contact space realized by the sequential method, the greater the change might be, which requires close follow-up in clinical practice.


Assuntos
Ajuste Oclusal , Dente , Força de Mordida , Dente Molar/cirurgia , Oclusão Dentária
12.
Biomater Sci ; 11(2): 489-498, 2023 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-36449365

RESUMO

The development of long-acting antiviral therapeutic delivery systems is crucial to improve the current treatment and prevention of HIV and chronic HBV. We report here on the conjugation of tenofovir (TFV), an FDA approved nucleotide reverse transcriptase inhibitor (NRTI), to rationally designed peptide amphiphiles (PAs), to construct antiviral prodrug hydrogelators (TFV-PAs). The resultant conjugates can self-assemble into one-dimensional nanostructures in aqueous environments and consequently undergo rapid gelation upon injection into 1× PBS solution to create a drug depot. The TFV-PA designs containing two or three valines could attain instantaneous gelation, with one displaying sustained release for more than 28 days in vitro. Our studies suggest that minor changes in peptide design can result in differences in supramolecular morphology and structural stability, which impacted in vitro gelation and release. We envision the use of this system as an important delivery platform for the sustained, linear release of TFV at rates that can be precisely tuned to attain therapeutically relevant TFV plasma concentrations.


Assuntos
Antivirais , Hidrogéis , Tenofovir/farmacologia , Adenina/farmacologia , Polímeros , Peptídeos
13.
ACS Appl Mater Interfaces ; 15(21): 25633-25649, 2023 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-37198933

RESUMO

A nanofiltration membrane functionalized with metal-organic frameworks (MOFs) is promising to enhance micropollutant removal and realize wastewater reclamation. However, the current MOF-based nanofiltration membranes still suffer from severe fouling problems with an indefinable mechanism when used for antibiotic wastewater treatment. Hence, we report a nature-inspired MOF-based thin-film nanocomposite (TFN-CU) membrane to explore its rejection and antifouling behavior. Compared with unmodified membranes, the optimal TFN-CU5 membrane (with 5 mg·mL-1 C-UiO-66-NH2) had high water permeance (17.66 ± 1.19 L·m-2·h-1·bar-1), exceptional rejection for norfloxacin (97.92 ± 2.28%) and ofloxacin (95.36 ± 1.03%), and excellent long-term stability for treating synthetic secondary effluent with antibiotic rejection over 90%. Furthermore, it also showed superior antifouling capability (flux recovery up to 95.86 ± 1.28%) in bovine serum albumin (BSA) filtration after fouling cycles. Deriving from the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach, the antifouling mechanism between BSA and the TFN-CU5 membrane was mainly attributed to the inhibited adhesion forces because the growing short-ranged acid-base interaction caused repulsive interfacial interactions. It is further revealed that BSA fouling behavior is slightly retarded under an alkaline environment, while strengthened in the presence of calcium ions and humic acid, as well as high ionic strength. In short, the nature-inspired MOF-based TFN membranes possess exceptional rejection and organic fouling resistance, giving insights into the design of antifouling membranes during antibiotic wastewater reclamation.


Assuntos
Estruturas Metalorgânicas , Nanocompostos , Águas Residuárias , Fluoroquinolonas , Antibacterianos/farmacologia , Membranas Artificiais
14.
Nat Commun ; 14(1): 2583, 2023 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-37142590

RESUMO

Hydrogels are promising soft materials as tissue engineering scaffolds, stretchable sensors, and soft robotics. Yet, it remains challenging to develop synthetic hydrogels with mechanical stability and durability similar to those of the connective tissues. Many of the necessary mechanical properties, such as high strength, high toughness, rapid recovery, and high fatigue resistance, generally cannot be established together using conventional polymer networks. Here we present a type of hydrogels comprising hierarchical structures of picot fibres made of copper-bound self-assembling peptide strands with zipped flexible hidden length. The redundant hidden lengths allow the fibres to be extended to dissipate mechanical load without reducing network connectivity, making the hydrogels robust against damage. The hydrogels possess high strength, good toughness, high fatigue threshold, and rapid recovery, comparable to or even outperforming those of articular cartilage. Our study highlights the unique possibility of tailoring hydrogel network structures at the molecular level to improve their mechanical performance.


Assuntos
Hidrogéis , Alicerces Teciduais , Hidrogéis/química , Engenharia Tecidual , Polímeros
15.
Mater Horiz ; 10(7): 2554-2567, 2023 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-37078123

RESUMO

Enhanced joint synergistic lubrication combined with anti-inflammatory therapy is an effective strategy to delay the progression of early osteoarthritis (OA) but has been rarely reported. The hydration lubrication of zwitterions and inherent super-lubrication properties of the cyclic brush, as well as the enhancement of the steric stability of the cyclic topology, can effectively improve the drug loading and utilization; herein we report a pH-responsive cyclic brush zwitterionic polymer (CB) with SBMA and DMAEMA as brushes and a cyclic polymer (c-P(HEMA)) as the core template, possessing a low coefficient of friction (0.017). After loading with hydrophobic curcumin and hydrophilic loxoprofen sodium it demonstrates high drug-loading efficiency. In vitro and in vivo experiments confirmed the triple function of the CB on superlubrication, sequence controlled release and anti-inflammatory effects demonstrated by Micro CT, histological analysis and qRT-PCR. Overall, the CB is a promising long-acting lubricating therapeutic agent, with potential for OA treatment or other diseases.


Assuntos
Osteoartrite , Polímeros , Humanos , Lubrificação , Polímeros/química , Osteoartrite/tratamento farmacológico , Sistemas de Liberação de Medicamentos , Concentração de Íons de Hidrogênio
16.
Langmuir ; 28(35): 12779-87, 2012 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-22913793

RESUMO

Owing to their many outstanding features, such as small size, large surface area, and cell penetration ability, nanoparticles have been increasingly used in medicine and biomaterials as drug carriers and diagnostic or therapeutic agents. However, our understanding of the interactions of biological entities, especially proteins, with nanoparticles is far behind the explosive development of nanotechnology. In typical protein-nanoparticle interactions, two processes (i.e., surface binding and conformational changes in proteins) are intermingled with each other and have not yet been quantitatively described. Here, by using a stopped-flow fast mixing technique, we were able to shed light on the kinetics of the adsorption-induced protein unfolding on nanoparticle surfaces in detail. We observed a biphasic denaturation behavior of protein GB1 on latex nanoparticle surfaces. Such kinetics can be adequately described by a fast equilibrium adsorption followed by a slow reversible unfolding of GB1. On the basis of this model, we quantitatively measured all rate constants that are involved in this process, from which the free-energy profile is constructed. This allows us to evaluate the effects of environmental factors, such as pH and ionic strength, on both the adsorption and the conformational change in GB1 on the latex nanoparticle surface. These studies provide a general physical picture of the adsorption-induced unfolding of proteins on nanoparticle surfaces and a quantitative description of the energetics of each transition. We anticipate that it will greatly advance our current understanding of protein-nanoparticle interactions and will be helpful for the rational control of such interactions in biomedical applications.


Assuntos
Proteínas de Bactérias/química , Nanopartículas/química , Desnaturação Proteica , Adsorção , Cinética , Látex/química , Soluções , Propriedades de Superfície
17.
Langmuir ; 28(46): 16133-40, 2012 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-23106398

RESUMO

Protein PEGylation (attaching PEG chains to proteins) has been widely used in pharmaceuticals and nanotechnology. Although it is widely known that PEGylation can increase the thermodynamic stability of proteins, the underlying mechanism remains elusive. In this Article, we studied the effect of PEGylation on the thermodynamic and kinetic stability of a protein, SH3. We show that the thermodynamic stability of SH3 is enhanced upon PEGylation, mainly due to the slowing of the unfolding rate. Moreover, PEGylation can decrease the solvent-accessible surface area of SH3, leading to an increase of the m-value (the change in free energy with respect to denaturant concentration, which is a measure of the transition cooperativity between corresponding states). Such an effect also causes an enhancement of the thermodynamic stability. We quantitatively measured how the physical properties of PEG, such as the molecular weight and the number of PEGylation sites, affect the stabilization effect. We found that the stabilization effect is largely dependent on the number of PEGylation sites but only has a weak correlation with the molecular weight of the attached PEG. These experimental findings inspire us to derive a physical model based on excluded volume effect, which can satisfactorily describe all experimental observations. This model allows quantitatively calculating the free energy change upon PEGylation based on the change of water excluded zone on the protein surface. Although it is still unknown whether such a mechanism can be extended to other proteins, our work represents a key step toward the understanding of the nature of protein stabilization upon PEGylation.


Assuntos
Polietilenoglicóis/química , Domínios de Homologia de src , Animais , Galinhas/genética , Dicroísmo Circular , Cinética , Modelos Químicos , Modelos Moleculares , Conformação Proteica , Dobramento de Proteína , Estabilidade Proteica , Termodinâmica , Quinases da Família src/química
18.
J Hazard Mater ; 433: 128801, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35405589

RESUMO

The ability of microplastics (MPs) to interact with environmental pollutants is of great concern. Riverine sediments, as sinks for multi-pollutants, have been rarely studied for MPs risk evaluation. Meanwhile, MPs generated from biodegradable plastics are questioning the safety of the promising materials. In this study, we investigated the effects of typical non-degradable polyethylene (PE) and biodegradable polylactic acid (PLA) MPs on sediment enzymes, arsenic (As) fractionation, and microbial community structures in As-contaminated riverine sediments. The results indicated that the presence of MPs (1% and 3%, w/w) led As transformed into more labile and bioavailable fractions in riverine sediments, especially under higher As and MPs levels. Analysis on microbial activities and community structures confirmed the strong potential of MPs in inhibiting microbial activities and shifting bacterial community succession patterns through enrichment of certain microbiota. Moreover, biodegradable PLA MPs presented stronger alterations in arsenic fractionation and microbial community structures than PE MPs did, which might be jointly attributed to adsorption behaviors, microbial alterations, and potential PLA degradation behaviors. The study indicated that MPs contamination increased As mobility and bioavailability, and shifted microbial communities in riverine sediments. Moreover, biodegradable MPs might lead to stronger microbial alterations and increases in As bioavailability, acting as a threat to ecological safety, which needed further exploration.


Assuntos
Arsênio , Microbiota , Poluentes Químicos da Água , Arsênio/análise , Arsênio/toxicidade , Microplásticos/toxicidade , Plásticos , Poliésteres , Polietileno , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
19.
Int J Biol Macromol ; 209(Pt B): 1882-1892, 2022 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-35489620

RESUMO

Elucidating the structural variations of lignin during the pretreatment is very important for lignin valorization. Herein, poplar wood was pretreated with an integrated process, which was composed of AlCl3-catalyzed hydrothermal pretreatment (HTP, 130-150 °C, 1.0 h) and mild deep-eutectic solvents (DES, 100 °C, 10 min) delignification for recycling lignin fractions. Confocal Raman Microscopy (CRM) was developed to visually monitor the delignification process during the HTP-DES pretreatment. NMR characterizations (2D-HSQC and 31P NMR) and elemental analysis demonstrated that the lignin fractions had undergone the following structural changes, such as dehydration, depolymerization, condensation. Molecular weights (GPC), microstructure (SEM and TEM), and antioxidant activity (DPPH analysis) of the lignins revealed that the DES delignification resulted in homogeneous lignin fragments (1.32 < PDI < 1.58) and facilitated the rapid assemblage of lignin nanoparticles (LNPs) with controllable nanoscale sizes (30-210 nm) and excellent antioxidant activity. These findings will enhance the understanding of structural transformations of the lignin during the integrated process and maximize the lignin valorization in a current biorefinery process.


Assuntos
Lignina , Populus , Antioxidantes/farmacologia , Biomassa , Solventes Eutéticos Profundos , Hidrólise , Lignina/química , Solventes/química
20.
J Colloid Interface Sci ; 624: 307-319, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-35660900

RESUMO

The aim of this study was to improve the bioavailability of polymyxin B (PMB) in pulmonary nebulized drug delivery. To this end, we developed a nano-delivery system that penetrates the mucus barrier of the lung. Hydrophilic hyaluronic acid (HA) was combined with a water-in-oil system containing a poly (lactic acid)-glycolic acid copolymer of PMB to prepare HA@PLGA-PMB nanoparticles (NPs) with good surface properties. HA@PLGA-PMB NPs with suitable electrical properties, particle size, and good hydrophilicity prevented strong interactions between the NPs and mucus, thereby allowing more drugs to enter deeper into the lung. Compared to the free drug PMB, NPs had more than 2-fold higher mucus penetration efficiency in vitro and better delivery to infected alveolar cells during in vivo nebulization. NPs had better biocompatibility, which further reduced the drug toxicity. More importantly, NPs showed better antimicrobial therapeutic efficacy in the treatment of lung infections in mice. These findings may provide support for the clinical application of nebulized pulmonary antibiotics.


Assuntos
Ácido Hialurônico , Nanopartículas , Animais , Portadores de Fármacos , Sistemas de Liberação de Medicamentos , Glicolatos , Ácido Láctico , Pulmão , Camundongos , Muco , Tamanho da Partícula , Ácido Poliglicólico , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Polimixina B/farmacologia
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