Ultrasensitive and Recyclable Upconversion‐Fluorescence Fibrous Indicator Paper with Plasmonic Nanostructures for Single Droplet Detection

Abstract

attention due to their extensive biological and medical applications. [1][2][3][4][5] Conventional indicator paper such as pH paper is disposable after use. Similarly, a traditional particulate-based fluorescence sensor is also not reusable because it usually suspends fluorescent nanoparticles such as quantum dots and upconversion nanocrystals in the target solution to initiate detection, [6][7][8][9] which are often unstable and irreproducible when contaminated by the target solution. Additionally, these indicator papers and fluorescence sensors usually need large amounts of the target solutions, which severely restricts their widespread application, especially for small amounts of target solutions, such as a single droplet. On the other hand, the sensitivities of current fluorescence indicator paper and sensors are still expected to improve because a higher sensitivity can respond to target solutions with a lower concentration, which will benefit the application of trace detection. [10,11] Therefore, it is highly desired to develop fluorescence indicator paper or sensor that simultaneously possesses excellent sensitivity and recyclability for single droplet detection.Among fluorescent nanoparticles, upconversion nanocrystals, compared with quantum dots, are attractive candidates because they can be excited by near-infrared light, which has a high penetration depth in biological tissues. [12,13] Moreover, fluorophores with stronger fluorescence can suppress background noise and autofluorescence, bringing about more sensitive detection. [14,15] To achieve stronger fluorescence, plasmonic nanostructures are good choices because they can produce strong localized electric fields, affecting excitation or emission process of nearby fluorophores to enhance their fluorescence; this process must not change the chemical construction of fluorophores, which is not an easy task. [16,17] Superhydrophobicity signifies that the material does not readily become damp, with a water contact angle over 150°. [18] To achieve recyclability, immediate contact of fluorescent nanoparticles with target solutions must be avoided. Utilizing electrospinning is a good method to achieve this, because it can easily incorporate nanoparticles into superhydrophobic nanofibers during the electrospinning process, [19][20][21][22] which endows them with a self-cleaning property. In addition, the large specific surface area of electrospun Conventional indicator paper is disposable after use and requires a large amount of target solution. Herein, recyclable upconversion fluorescence indicator papers consisting of upconversion nanorods and plasmonic nanostructures are fabricated by electrospinning. This recyclable indicator paper exhibits good flexibility and superhydrophobicity with enhanced upconversion fluorescence. Rhodamine B (RhB) is selected as the target solution because it is prohibited as a food additive but often occurs in food, and conventional detection methods usually need a large volume of solution (>1 mL) to refine to higher concentratio...

Activators Confined Upconversion Nanoprobe with Near-Unity Förster Resonance Energy Transfer Efficiency for Ultrasensitive Detection

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Self-powered portable melt electrospinning for in situ wound dressing

“…In order to achieve in situ melt e-spinning, the conventional melt e-spinning device is an option [20][21][22][23][24][25][26][27][28][29][30][31]. However, these conventional melt e-spinning devices usually use a heating method such as resistance wires [22,23], laser heating [24,25], microwave heating [26], heated air and oil liquid [26][27][28][29][30][31] which need mains supply to melt the polymer for subsequent e-spinning, which is inconvenient in practical clinical and practical applications, especially where is no mains supply in the wild outdoors. In order to solve the problem of relying on the mains supply, the previous research used heating methods such as alcohol lamps, candles, etc.…”

Compósitos de Fluoretos de Terras Raras em Hidroxipropilmetilcelulose com conversão ascendente intensificada por ressonância plasmônica de superfície

“…33 1.5. Compósitos poliméricos com conversão ascendente Compósitos que apresentam conversão ascendente tem grande destaque na literatura, principalmente na área biomédica junto à teranósticos 25,34 , termômetros 35 e energias alternativas 19 . O uso de UCNps em polímeros é recorrente, sendo primariamente utilizados em sistemas eletrofiados 36 .…”