sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles - overhead document projector

Since the advent of modern means of transport, heavy metal pollution has been a problem, and despite efforts to control emissions, it still plays a key role in environmental pollution. Copper ions (Cu2+)
In particular, this metal is one of the more common metals with a wide range of harmful effects.
From this point of view, a simple and inexpensive way to detect copper at the micro-molar level is ideal.
In this study, we use porous silicon nanoparticles (NPs)
, Obtained by the anode etching of the silicon wafer, as the basis of the eleven acid (UDA)-
Or acrylic (AA)-
Hydrogen-mediated silicon.
The resulting hydrocarbons-
Terminated porous silicon nanoparticles (APS NPs)
Enhanced Fluorescence stability and strength, and, more importantly, demonstrated [Cu2+]-
The dependence of fluorescence is extinguished.
After determining the various water sensing conditions for copper, we show the use of APS NPs in two different applications-one standard well --
Paper-based kit and portable layer-by-Layer stick kit.
Overall, we demonstrate the potential of APS NPs to effectively detect copper in sensors. N-type, As-
Doping silicon wafers with a diameter of 500mm (2 in)
The orientation degree is and the resistivity is 0. 001–0.
01 Ω cm was used in this study.
Si wafer was electrolytic corroded in HF-HO-ethyl-alcohol (1:1:4 v/v)
According to the procedure reported elsewhere, the mixture after lateral etching.
To put it simply, anode etching is carried out in a polycarbonate battery with a size of 150 × 60 × 50.
The silicon wafer is located between the Pt lines of the grid on the parallel Teflon board, and the electrical contact is provided with silver paste to the top edge of the silicon wafer.
Pump the electrolyte slowly into the battery (
Cole Palmer Masterflex L/S pump USA)
The speed is 5 ml/min.
At a constant current of 120-2 50 ma, the total etching time is about 1 hr (
Model PS300c, SolGent, South Korea).
After anode etching, wash the wafer with a large amount of deionized water and methanol (
HPLC grade of Fisher)
Dry with nitrogen.
The dried wafer is strongly orange-red or yellow-
Blue glow at 365 or 254 nm excitation, respectively.
The dry wafer was then treated with 20 ml ethanol for 90 minutes by ultrasound.
The suspension system of ultrasonic treatment is brown, showing a unique broadband PL at about 365 nm.
In the suspension of centrifugal 13,000 will . . . . . . (=u20099. 81u2009m s)
The time to separate PS NPs is 10 minutes.
Pause aps np with AA (
10wt % in ethanol)
First foam with N to remove any dissolved oxygen that may inhibit free radicals
Reaction caused
Next, the ps np suspended solids are placed in a photo reactor (
Rayonet, southern New England, USA)
Equipped with 10 UV tubes (RPR-
New England Southern UV Ltd. , USA)
Lead to hydrogen addition reaction of silicon;
The reaction lasted for 24 hours at 40 °c and resulted in a noticeable pause.
Generate UDA-
PS NPs, 20 ml of PS NPs was transferred to three-
Neck bottle with UDA (
10wt % in ethanol)
Heat at 95 °c for 16 u2009 h and stir continuously in a nitrogen atmosphere.
After the silicon hydrogen addition reaction of PS NPs with UDA, the turbid suspension becomes transparent.
Both types of suspension were centrifuge for 10 min at 13,000 °f to separate APS NPs and then wash NPs with ethanol and then centrifuge three more times to ensure thorough washing.
Finally, add 500 μl de-ionic water to re-hang APS NPs.
Results The aps np pause is displayed as orange-
Red flowering period below 365-nm excitation.
UDA-was observed with 10mm Fe, Na, K, Mg, Mn Ca and Cu-PS NPs in water200u2009μL of UDA-
Ps np solution is placed in a 96-well plate, after which each ion is added to 10 μ l in each hole.
End-point fluorescence measurements were performed at a wavelength of 665 nm.
Whatman cellulose filter paper no.
1 is cut into pieces measuring mm × 85mm to fit in a microplate reader.
We designed a 96. Paper kit (
Adobe Illustrator CS6, Adobe, USA)with 5-mm-
Diameter holes in each hole that hold a sample of 20 μ l aps np.
Printing with wax paper printer for paper kit (
ColorQube 8570, Xerox, Japan)
After that, the printing paper is baked at 30 °c for 3 min, and the wax ink is melted onto the paper to form a drain wall around each hole.
A piece of Parafilm is then attached under the paper sleeve to prevent any liquid from leaking from the well.
Finally, place the paper bag on a polypropylene board to deliver to the microplate reader stably.
By dripping the 20 μ l microliter particle solution into each hole, the aqueous solution of APS NPs is coated on the paper kit.
The paper bag is then stored in a vacuum drying oven at 40 °c and 76 °c for 1 hour.
The whole process was repeated five times, and then the holes showed bright PL under UV excitation at 356 nm. bPEI (=u2009~2,000)
Bought from Sigma. Aldrich, USA.
BPEI and APS NPs were dissolved in ethanol at a concentration of 1 mg/kg, respectively.
A curing agent and a silicone rubber premix (
SYLGARD 184 Silicone elastic kit Dow Corning USA)
Mix thoroughly at a ratio of 1: 10 v/v.
The premix is poured into a substrate made of a projector (OHP)
Transparent film, and cured in a vacuum oven at 100 ° C for 3 ° h.
After curing, the silicone rubber copy of the film is stripped from the substrate and LbL film is prepared on it. The PDMS-
Patterned OHP film substrate cleaned and modified by oxygen
Plasma therapy (CUTE-
Femto Science, USA.
Multi-layer (bPEI/pSiNP)
Then the film is prepared as follows.
First, add 20 μ l droplets of bPEI solution to silicone rubber-
Patterned OHP film substrates and silicon wafers, and allow the placement of 10 µmin to enable hydrogen bonding between the oh base on the substrate surface and the amine base of bPEI.
Subsequently washed three times in the ethanol stream, eliminating any weak-bound bPEI.
Then add the droplets of 20 μ l aps np solution to bPEI-
Coating the surface in a similar way and washing with ethanol.
APS NPs was characterized by TEM. TEM and high-Resolution TEM (HRTEM)
Obtained images with the Movement of Justice and Equality
2100F microscope (JEOL, Japan)
Under the acceleration voltage of 200kv kv.
NP for preparation of fast-drying drops in transmission electron microscope samples hanging on ethanol 300
Mesh copper mesh coated with carbon film.
Recording PL and UV absorption spectra of APS NPs using Synergy Mx (Biotek Inc. , USA).
Particle size distribution and dynamic potential analysis of APS NPs using dynamic light
Scattering system (
Zetasizer, Malvin, UK)and TEM.
Calculate quenching efficiency (Δ%)
PL, PL standard strength ()
Compared with the reduced PL strength ()
At the same time, the same values of excitation intensity, absorbance and other instrument parameters are maintained.
Get the quenching PL strength ratio in percentage: evaluate the growth, thickness and degradation rate of the film using a contour meter (Dektak 150). FE-
SEM images were obtained by scanning electron microscopy (
Carl Zeiss, Germany).
The extinction efficiency of copper ions on APS NPs was evaluated by adding 200 μ l aps np solution to 96 holes, after which copper ions solution was added in Wells with a considerable initial PL strength level were selected.
Similarly, the copper ion pair UDA-
PS NPs on paper-
The kit-based was measured by adding 10 μ l standard copper ion solution to a completely dry paper kit.
Contains other data on the properties of APS NPs, including extinction selectivity, quantum yield, extinction efficiency, fluorescence stability in biological fluids, and thickness of nano-film containing NPs.