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1.
Lab Chip ; 20(8): 1441-1448, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32211667

RESUMO

A wide range of microfluidic paper-based analytical devices (µPADs) have been developed in the last decade. Despite this, the quality of colorimetric analysis has not substantially improved as the data is vulnerable to heterogeneous color distribution (e.g., coffee ring effects), non-uniform shapes of colored detection area, and noise from the underlying paper structure. These limitations are here addressed by a colorimetric method to quantify freely discharged dye on paper substrate, without the need for a defined channel or hydrophobic barrier. For accurate quantification, colorimetric absorbance values are calculated for each pixel based on the recorded RGB values and noise from the paper structure eliminated, to extract accurate absorbance information at the pixel level. Total analyte quantity is then calculated through the conversion of absorbance values into quantity values for each pixel followed by integration across the entire image. The resulting quantity is shown to be independent of the shape of the applied colored dye spot, with a cross, circle or rod shape all giving the same quantity information. The approach is applied to a capillary-based potassium-selective sensor, where the sample solution is loaded with the dye thioflavin T (ThT) obtained by quantitative exchange with K+ in a sensing capillary, which is discharged onto a bare paper substrate without any channels. The resulting dye quantity is successfully obtained by flatbed scanner and smartphone. The successful automated computation of colorimetric data on µPADs will help realize simpler paper-based assay and reaction systems that should be more applicable to addressing real world analytical problems.

2.
ACS Appl Mater Interfaces ; 11(38): 34676-34687, 2019 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-31483991

RESUMO

Nanoparticle-cell interactions between silica nanomaterials and mammalian cells have been investigated extensively in the context of drug delivery, diagnostics, and imaging. While there are also opportunities for applications in infectious disease, the interactions of silica nanoparticles with pathogenic microbes are relatively underexplored. To bridge this knowledge gap, here, we investigate the effects of organosilica nanoparticles of different sizes, concentrations, and surface coatings on surface association and viability of the major human fungal pathogen Candida albicans. We show that uncoated and PEGylated organosilica nanoparticles associate with C. albicans in a size and concentration-dependent manner, but on their own, do not elicit antifungal activity. The particles are also shown to associate with human white blood cells, in a similar trend as observed with C. albicans, and remain noncytotoxic toward neutrophils. Smaller particles are shown to have low association with C. albicans in comparison to other sized particles and their association with blood cells was also observed to be minimal. We further demonstrate that by chemically immobilizing the clinically important echinocandin class antifungal drug, caspofungin, to PEGylated nanoparticles, the cell-material interaction changes from benign to antifungal, inhibiting C. albicans growth when provided in high local concentration on a surface. Our study provides the foundation for defining how organosilica particles could be tailored for clinical applications against C. albicans. Possible future developments include designing biomaterials that could detect, prevent, or treat bloodstream C. albicans infections, which at present have very high patient mortality.


Assuntos
Antifúngicos , Candida albicans/crescimento & desenvolvimento , Materiais Revestidos Biocompatíveis , Nanopartículas , Neutrófilos/metabolismo , Compostos de Organossilício , Polietilenoglicóis , Antifúngicos/química , Antifúngicos/farmacologia , Candidíase/tratamento farmacológico , Candidíase/metabolismo , Candidíase/patologia , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Humanos , Nanopartículas/química , Nanopartículas/uso terapêutico , Compostos de Organossilício/química , Compostos de Organossilício/farmacologia , Polietilenoglicóis/química , Polietilenoglicóis/farmacologia
3.
Langmuir ; 35(5): 1266-1272, 2019 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-29801414

RESUMO

Development of antifouling films which selectively capture or target proteins of interest is essential for controlling interactions at the "bio/nano" interface. However, in order to synthesize biofunctional films from synthetic polymers that incorporate chemical "motifs" for surface immobilization, antifouling, and oriented biomolecule attachment, multiple reaction steps need to be carried out at the solid/liquid interface. EKx is a zwitterionic peptide that has previously been shown to have excellent antifouling properties. In this study, we recombinantly expressed EKx peptides and genetically encoded both surface attachment and antibody-binding motifs, before characterizing the resultant biopolymers by traditional methods. These peptides were then immobilized to organosilica nanoparticles for binding IgG, and subsequently capturing dengue NS1 as a model antigen from serum-containing solution. We found that a mixed layer of a short peptide (4.9 kDa) "backfilled" with a longer peptide terminated with an IgG-binding Z-domain (18 kDa) demonstrated selective capture of dengue NS1 protein down to ∼10 ng mL-1 in either PBS or 20% serum.


Assuntos
Incrustação Biológica/prevenção & controle , Imunoglobulina G/metabolismo , Peptídeos/metabolismo , Proteínas Recombinantes/metabolismo , Vírus da Dengue/química , Escherichia coli/genética , Proteínas Imobilizadas/genética , Proteínas Imobilizadas/metabolismo , Imunoglobulina G/química , Nanopartículas/química , Peptídeos/genética , Ligação Proteica , Domínios Proteicos , Engenharia de Proteínas/métodos , Proteínas Recombinantes/genética , Dióxido de Silício/química , Proteínas não Estruturais Virais/metabolismo
4.
ACS Sens ; 3(5): 967-975, 2018 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-29634243

RESUMO

Continuous monitoring using nanoparticle-based sensors has been successfully employed in complex biological systems, yet the sensors still suffer from poor long-term stability partially because of the scaffold materials chosen to date. Organosilica core-shell nanoparticles containing a mixture of covalently incorporated pH-sensitive (shell) and pH-insensitive (core) fluorophores is presented as a continuous pH sensor for application in biological media. In contrast to previous studies focusing on similar materials, we sought to investigate the sensor characteristics (dynamic range, sensitivity, response time, stability) as a function of material properties. The ratio of the fluorescence intensities at specific wavelengths was found to be highly sensitive to pH over a physiologically relevant range (4.5-8) with a response time of <100 ms, significantly faster than that of previously reported response times using silica-based particles. Particles produced stable, pH-specific signals when stored at room temperature for more than 80 days. Finally, we demonstrated that the nanosensors successfully monitored the pH of a bacterial culture over 15 h and that pH changes in the skin of mouse cadavers could also be observed via in vivo fluorescence imaging following subcutaneous injection. The understanding gained from linking sensor characteristics and material properties will inform the next generation of optical nanosensors for continuous-monitoring applications.


Assuntos
Técnicas Biossensoriais/instrumentação , Concentração de Íons de Hidrogênio , Nanopartículas/química , Compostos Orgânicos/química , Dióxido de Silício/química , Animais , Bactérias/química , Meios de Cultura , Camundongos , Microscopia Eletrônica de Varredura , Imagem Óptica , Espectroscopia Fotoeletrônica , Pele/química
5.
Langmuir ; 33(3): 773-782, 2017 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-28006902

RESUMO

Immunoassays are ubiquitous across research and clinical laboratories, yet little attention is paid to the effect of the substrate material on the assay performance characteristics. Given the emerging interest in wearable immunoassay formats, investigations into substrate materials that provide an optimal mix of mechanical and bioanalytical properties are paramount. In the course of our research in developing wearable immunoassays which can penetrate skin to selectively capture disease antigens from the underlying blood vessels, we recently identified significant differences in immunoassay performance between gold and polycarbonate surfaces, even with a consistent surface modification procedure. We observed significant differences in PEG density, antibody immobilization, and nonspecific adsorption between the two substrates. Despite a higher PEG density formed on gold-coated surfaces than on amine-functionalized polycarbonate, the latter revealed a higher immobilized capture antibody density and lower nonspecific adsorption, leading to improved signal-to-noise ratios and assay sensitivities. The major conclusion from this study is that in designing wearable bioassays or biosensors, the design and its effect on the antifouling polymer layer can significantly affect the assay performance in terms of analytical specificity and sensitivity.


Assuntos
Ensaio de Imunoadsorção Enzimática/instrumentação , Polietilenoglicóis/química , Adsorção , Animais , Ouro/química , Imunoglobulina G/química , Camundongos , Cimento de Policarboxilato/química , Silício/química , Propriedades de Superfície
6.
Pharm Res ; 33(10): 2373-87, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27299311

RESUMO

In this review we provide an up to date snapshot of nanomedicines either currently approved by the US FDA, or in the FDA clinical trials process. We define nanomedicines as therapeutic or imaging agents which comprise a nanoparticle in order to control the biodistribution, enhance the efficacy, or otherwise reduce toxicity of a drug or biologic. We identified 51 FDA-approved nanomedicines that met this definition and 77 products in clinical trials, with ~40% of trials listed in clinicaltrials.gov started in 2014 or 2015. While FDA approved materials are heavily weighted to polymeric, liposomal, and nanocrystal formulations, there is a trend towards the development of more complex materials comprising micelles, protein-based NPs, and also the emergence of a variety of inorganic and metallic particles in clinical trials. We then provide an overview of the different material categories represented in our search, highlighting nanomedicines that have either been recently approved, or are already in clinical trials. We conclude with some comments on future perspectives for nanomedicines, which we expect to include more actively-targeted materials, multi-functional materials ("theranostics") and more complicated materials that blur the boundaries of traditional material categories. A key challenge for researchers, industry, and regulators is how to classify new materials and what additional testing (e.g. safety and toxicity) is required before products become available.


Assuntos
Ensaios Clínicos como Assunto , Aprovação de Drogas , Nanomedicina/tendências , Nanopartículas/administração & dosagem , Ensaios Clínicos como Assunto/legislação & jurisprudência , Ensaios Clínicos como Assunto/métodos , Aprovação de Drogas/métodos , Humanos , Nanomedicina/legislação & jurisprudência , Nanopartículas/metabolismo , Distribuição Tecidual/efeitos dos fármacos , Distribuição Tecidual/fisiologia , Estados Unidos/epidemiologia
7.
Biointerphases ; 10(4): 04A305, 2015 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-26446192

RESUMO

Selective capture of disease-related proteins in complex biological fluids and tissues is an important aim in developing sensitive protein biosensors for in vivo applications. Microprojection arrays are biomedical devices whose mechanical and chemical properties can be tuned to allow efficient penetration of skin, coupled with highly selective biomarker capture from the complex biological environment of skin tissue. Herein, the authors describe an improved surface modification strategy to produce amine-modified polycarbonate arrays, followed by the attachment of an antifouling poly(sulfobetaine-methacrylate) (pSBMA) polymer or a linear polyethylene glycol (PEG) polymer of comparative molecular weight and hydrodynamic radius. Using a "grafting to" approach, pSBMA and linear PEG coatings yielded comparative antifouling behavior in single protein solutions, diluted plasma, or when applied to mouse flank skin penetrating into the vascularized dermal tissue. Interestingly, the density of immobilized immunoglobulin G (IgG) or bovine serum albumin protein on pSBMA surfaces was significantly higher than that on the PEG surfaces, while the nonspecific adsorption was comparable for each protein. When incubated in buffer or plasma solutions containing dengue non-structural protein 1 (NS1), anti-NS1-IgG-coated pSBMA surfaces captured significantly more NS1 in comparison to PEG-coated devices. Similarly, when wearable microprojection arrays were applied to the skin of dengue-infected mice using the same coatings, the pSBMA-coated devices showed significantly higher capture efficiency (>2-fold increase in signal) than the PEG-coated substrates, which showed comparative signal when applied to naïve mice. In conclusion, zwitterionic pSBMA polymers (of equivalent hydrodynamic radii to PEG) allowed detection of dengue NS1 disease biomarker in a preclinical model of dengue infection, showing significantly higher signal-to-noise ratio in comparison to the PEG controls. The results of this study will be useful in the future development of a range of protein biosensors designed for use in vivo.


Assuntos
Adsorção , Antígenos/metabolismo , Incrustação Biológica/prevenção & controle , Técnicas Biossensoriais , Metacrilatos/química , Polietilenoglicóis/química , Propriedades de Superfície , Animais , Antígenos Virais/análise , Dengue/diagnóstico , Modelos Animais de Doenças , Equipamentos e Provisões , Camundongos
8.
Anal Chem ; 86(20): 10474-83, 2014 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-25232916

RESUMO

Herein we demonstrate the use of a wearable device that can selectively capture two distinct circulating protein biomarkers (recombinant P. falciparum rPfHRP2 and total IgG) from the intradermal fluid of live mice in situ, for subsequent detection in vitro. The device comprises a microprojection array that, when applied to the skin, penetrates the outer skin layers to interface directly with intradermal fluid. Because of the complexity of the biological fluid being sampled, we investigated the effects of solution conditions on the attachment of capture antibodies, to optimize the assay detection limit both in vitro and on live mice. For detection of the target antigen diluted in 20% serum, immobilization conditions favoring high antibody surface density (low pH, low ionic strength) resulted in 100-fold greater sensitivity in comparison to standard conditions, yielding a detection limit equivalent to the plate enzyme-linked immunosorbent assay (ELISA). We also show that blocking the device surface to reduce nonspecific adsorption of target analyte and host proteins does not significantly change sensitivity. After injecting mice with rPfHRP2 via the tail vein, we compared analyte levels in both plasma and skin biopsies (cross-sectional area same as the microprojection array), observing that skin samples contained the equivalent of ∼8 µL of analyte-containing plasma. We then applied the arrays to mice, showing that surfaces coated with a high density of antibodies captured a significant amount of the rPfHRP2 target while the standard surface showed no capture in comparison to the negative control. Next, we applied a triplex device to both control and rPfHRP2-treated mice, simultaneously capturing rPfHRP2 and total IgG (as a positive control for skin penetration) in comparison to a negative control device. We conclude that such devices can be used to capture clinically relevant, circulating protein biomarkers of infectious disease via the skin, with potential applications as a minimally invasive and lab-free biomarker detection platform.


Assuntos
Biomarcadores/sangue , Análise Química do Sangue/métodos , Malária Falciparum/diagnóstico , Plasmodium falciparum/química , Adesivo Transdérmico , Animais , Ensaio de Imunoadsorção Enzimática , Camundongos
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