Glucose-Induced Transition among Three States of a Doped Microgel Colloidal Crystal

Abstract

For the first time here, we report a colloid crystal capable of undergoing transition among three states in response to external stimuli. The colloidal crystal was assembled from poly( N-isopropylacrylamide) (PNIPAM) microgel and doped with poly( N-isopropylacrylamide- co-2-acrylamido-phenylboronic acid) (P(NIPAM-2-AAPBA)) microgel. The ordered structure was locked by in situ photopolymerization. Taking advantage of the different responses of the two microgels to external stimuli, defect state can be induced and erased reversibly. Particularly, because the dopant, that is, P(NIPAM-2-AAPBA) microgel sphere, shrinks with increasing glucose concentration, its size changes from larger than the host, that is, PNIPAM microgel sphere, to equal to the host, and finally smaller than the host. Therefore, upon addition of glucose, the crystal undergoes transition from a state with acceptor-type defect, to no defect state, and then to a state with donor-type defect. The transition among the three states is fully reversible. In addition, the response of the doped crystal to glucose is relatively fast.

Glucose-Triggered Micellization of Poly(ethylene glycol)-b-poly(N-isopropylacrylamide-co-2-(acrylamido)phenylboronic acid) Block Copolymer

“…Here, on the basis of a new glucose-sensitive mechanism we proposed recently, − we described a new PBA-containing glucose-sensitive block copolymer that will self-assemble into micelles upon the addition of glucose. For the previously reported glucose-sensitive block copolymers, a 3- or 4-substituted PBA was usually used. ,, These PBA groups exist predominately as a hydrophobic, undissociated form.…”

“…To render the PBA-functionalized block thermosensitive, NIPAM was used as the main comonomer. The dominant structure of PBA groups in the copolymer is the negatively charged, tetrahedral structure, because the intramolecular B–O coordinated interaction stabilizes this structure (Scheme B). − The addition of glucose decreases the lower critical solution temperature (LCST) of the P­(NIPAM-2-AAPBA) block and turns the block from hydrophilic to hydrophobic. , Therefore, the addition of glucose triggers the micellization of the block copolymer (Scheme B) instead of the disassembly of micelles. To the best of our knowledge, this is the first example of glucose-induced micellization of block copolymers.…”

Layer-by-Layer Assembly of Microgel Colloidal Crystals via Photoinitiated Alkyne–Azide Click Reaction

“…We then coupled the carboxylic acid groups in the microgels with 11-azido-3,6,9-trioxaundecan-1-amine or propargylamine under N -(3-dimethylaminopropyl)- N ′-ethylcarbodiimide hydrochloride (EDC) catalysis to introduce azide or alkyne groups (Scheme A). A similar procedure was previously used to introduce other functional groups, e.g., phenylboronic acids, into the PNIPAM microgels. − The successful modification of microgels was confirmed by the appearance of new peaks at 3.77 and 3.56 ppm (−N–CH 2 –C H 2 –O–C H 2 –C H 2 –O–C H 2 –C H 2 –O–CH 2 –CH 2 –N 3 ) or 2.73 ppm (−N–CH 2 –CC– H ) in the 1 H NMR spectra of the corresponding microgels (Figure S2). Considering the remaining amounts of AAc in the microgels, as determined again by pH titration, ∼47.0 or ∼37.3% of the AAc groups were coupled with azide or alkyne groups, respectively (Figures S3 and S4).…”

An Insight into Skeletal Networks Analysis for Smart Hydrogels

“…In addition, Zhang and co-workers have also reported the novel sensing principle based on the order-disorder transition in doped microgel colloidal crystals, which is also an improvement on the response signal of CCA devices (Figure 6B). [163,164] The function of the CCA devices is no longer limited to indirect characterization of the deformation degree of hydrogels. Generally, there are three typical CCA devices, which to a certain extent reflect the advanced evolution of PCCA hydrogels over the past two decades.…”

“…Glu-sensitive layer-by-layer hydrogel films [145] 2D CCA devices [146,147] Glu-sensitive microgels [148] Hg 2+ responsive DNA-modified microgels [149] CCA devices Quantum dots [155] Hollow polymeric particles [156] Inverse opal [157,158] Opal [160] Janus particles [161] Microgel beads [162] Order-disorder transition [163,164] Spectroscopy Fabry-Perot fringes [114,166] Debye diffraction ring [167,168] Diffraction gratings [169] Plasmonic spectrum [170] Electrical signals Resistance of the conductive polymers [173][174][175][176] Wearable soft electronic devices [177] Microscopic deformation Traction force microscopy [179] SNR Colorimetry DNA-based responsive hydrogels [127] Enzymatic reaction Amylose-I 2 -amylase [126] "Sweet" concept [135] GOx-HRP cascade reaction [136] Volumetric bar-chart chip readout Move of an ink bar in the Chip [134] Electronic balance as readout [180] Fluorescence FRET phenomenon [181] perchlorate as the mobile phase, Asher and co-workers have reported the 2D PCCA hydrogels for atmospheric analytes detection. [189] Benefiting from the negligible ionic liquid vapor pressure, the responsive hydrogels were indefinitely air-stable.…”