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Nat Commun ; 11(1): 5995, 2020 11 25.
Artigo em Inglês | MEDLINE | ID: mdl-33239609


Infectious diseases are worldwide a major cause of morbidity and mortality. Fast and specific detection of pathogens such as bacteria is needed to combat these diseases. Optimal methods would be non-invasive and without extensive sample-taking/processing. Here, we developed a set of near infrared (NIR) fluorescent nanosensors and used them for remote fingerprinting of clinically important bacteria. The nanosensors are based on single-walled carbon nanotubes (SWCNTs) that fluoresce in the NIR optical tissue transparency window, which offers ultra-low background and high tissue penetration. They are chemically tailored to detect released metabolites as well as specific virulence factors (lipopolysaccharides, siderophores, DNases, proteases) and integrated into functional hydrogel arrays with 9 different sensors. These hydrogels are exposed to clinical isolates of 6 important bacteria (Staphylococcus aureus, Escherichia coli,…) and remote (≥25 cm) NIR imaging allows to identify and distinguish bacteria. Sensors are also spectrally encoded (900 nm, 1000 nm, 1250 nm) to differentiate the two major pathogens P. aeruginosa as well as S. aureus and penetrate tissue (>5 mm). This type of multiplexing with NIR fluorescent nanosensors enables remote detection and differentiation of important pathogens and the potential for smart surfaces.

Nat Commun ; 11(1): 1495, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32198383


Imaging of complex (biological) samples in the near-infrared (NIR) is beneficial due to reduced light scattering, absorption, phototoxicity, and autofluorescence. However, there are few NIR fluorescent materials known and suitable for biomedical applications. Here we exfoliate the layered pigment CaCuSi4O10 (Egyptian Blue, EB) via ball milling and facile tip sonication into NIR fluorescent nanosheets (EB-NS). The size of EB-NS can be tailored to diameters <20 nm and heights down to 1 nm. EB-NS fluoresce at 910 nm and the fluorescence intensity correlates with the number of Cu2+ ions. Furthermore, EB-NS display no bleaching and high brightness compared with other NIR fluorophores. The versatility of EB-NS is demonstrated by in-vivo single-particle tracking and microrheology measurements in Drosophila melanogaster embryos. EB-NS can be uptaken by plants and remotely detected in a low-cost stand-off detection setup. In summary, EB-NS have the potential for a wide range of bioimaging applications.

Corantes Fluorescentes/efeitos da radiação , Raios Infravermelhos , Imagem Óptica/métodos , Óptica e Fotônica/métodos , Silicatos/efeitos da radiação , Animais , Cobre , Drosophila melanogaster/embriologia , Fluorescência , Íons , Modelos Teóricos , Nanopartículas
J Biophotonics ; 13(1): e201960080, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31602799


Multispectral imaging combines the spectral resolution of spectroscopy with the spatial resolution of imaging and is therefore very useful for biomedical applications. Currently, histological diagnostics use mainly stainings with standard dyes (eg, hematoxylin + eosin) to identify tumors. This method is not applicable in vivo and provides low amounts of chemical information. Biomolecules absorb near infrared light (NIR, 800-1700 nm) at different wavelengths, which could be used to fingerprint tissue. Here, we built a NIR multispectral absorption imaging setup to study skin tissue samples. NIR light (900-1500 nm) was used for homogenous wide-field transmission illumination and detected by a cooled InGaAs camera. In this setup, images I(x, y, λ) from dermatological samples (melanoma, nodular basal-cell carcinoma, squamous-cell carcinoma) were acquired to distinguish healthy from diseased tissue regions. In summary, we show the potential of multispectral NIR imaging for cancer diagnostics.

Nano Lett ; 19(9): 6604-6611, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31418577


Serotonin is an important neurotransmitter involved in various functions of the nervous, blood, and immune system. In general, detection of small biomolecules such as serotonin in real time with high spatial and temporal resolution remains challenging with conventional sensors and methods. In this work, we designed a near-infrared (nIR) fluorescent nanosensor (NIRSer) based on fluorescent single-walled carbon nanotubes (SWCNTs) to image the release of serotonin from human blood platelets in real time. The nanosensor consists of a nonbleaching SWCNT backbone, which is fluorescent in the beneficial nIR tissue transparency window (800-1700 nm) and a serotonin binding DNA aptamer. The fluorescence of the NIRSer sensor (995 nm emission wavelength for (6,5)-SWCNTs) increases in response to serotonin by a factor up to 1.8. It detects serotonin reversibly with a dissociation constant of 301 nM ± 138 nM and a dynamic linear range in the physiologically relevant region from 100 nM to 1 µM. As a proof of principle, we detected serotonin release patterns from activated platelets on the single-cell level. Imaging of the nanosensors around and under the platelets enabled us to locate hot spots of serotonin release and quantify the time delay (≈ 21-30 s) between stimulation and release in a population of platelets, highlighting the spatiotemporal resolution of this nanosensor approach. In summary, we report a nIR fluorescent nanosensor for the neurotransmitter serotonin and show its potential for imaging of chemical communication between cells.

Técnicas Biossensoriais , Plaquetas/metabolismo , Corantes Fluorescentes/química , Nanotubos de Carbono/química , Serotonina/metabolismo , Plaquetas/ultraestrutura , Humanos
Nanoscale ; 11(23): 11159-11166, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31149692


Single-walled carbon nanotubes (SWCNTs) have unique photophysical properties and serve as building blocks for biosensors, functional materials and devices. For many applications it is crucial to use chirality-pure SWCNTs, which requires sophisticated processes. Purification procedures such as wrapping by certain polymers, phase separation, density gradient centrifugation or gel chromatography have been developed and yield distinct SWCNT species wrapped by a specific polymer or surfactant. However, many applications require a different organic functionalization (corona) around the SWCNTs instead of the one used for the purification process. Here, we present a novel efficient and straightforward process to gain chirality pure SWCNTs with tunable functionalization. Our approach uses polyfluorene (PFO) polymers to enrich certain chiralities but the polymer is removed again and finally exchanged to any desired organic phase. We demonstrate this concept by dispersing SWCNTs in poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(6,6'-{2,2'-bipyridine})] (PFO-BPy), which is known to preferentially solubilize (6,5)-SWCNTs. Then PFO-BPy is removed and recycled, while letting the SWCNTs adsorb/agglomerate on sodium chloride (NaCl) crystals, which act as a toluene-stable but water-soluble filler material. In the last step these purified SWCNTs are redispersed in different polymers, surfactants and ssDNA. This corona phase exchange purification (CPEP) approach was also extended to other PFO variants to enrich and functionalize (7,5)-SWCNTs. CPEP purified and functionalized SWCNTs display monodisperse nIR spectra, which are important for fundamental studies and applications that rely on spectral changes. We show this advantage for SWCNT-based nIR fluorescent sensors for the neurotransmitter dopamine and red-shifted sp3 defect peaks . In summary, CPEP makes use of PFO polymers for chirality enrichment but provides access to chirality enriched SWCNTs functionalized in any desired polymer, surfactant or biopolymer.