Abstract
Hollow microgels and their hybrids have gained much attention in modern-day research because of their fascinating properties and potential applications. This article gives classification, preparation methods, properties and applications of hollow microgels and their hybrids in modern research. Some of the hollow microgels and their hybrids respond to change in specific environmental stimuli like pH, ionic strength and temperature of the medium. They are called smart polymer hollow microgels and smart hybrid microgels, respectively. This peculiar behaviour makes them a suitable candidate for their use in drug delivery, sensing, catalysis and many other fields. This review represents the current advancement along with future perspectives and suggestions for further research in this particular area.
About the authors
Ahmad Hassan is presently enrolled in M.Phil. Chemistry at School of Chemistry, University of the Punjab (PU), Lahore, Pakistan, under the supervision of Dr. Farooqi. He obtained his BS degree in Chemistry from the same institute in 2021. His area of research is polymer stabilized metal nanoparticles for catalysis.
Iqra Sajid is presently enrolled in M.Phil. Chemistry at School of Chemistry, University of the Punjab (PU), Lahore, Pakistan, under the supervision of Dr. Farooqi. She obtained her BS degree in Chemistry from the same institute in 2021. She completed her BS dissertation under the supervision of Dr. Farooqi. Her area of research is polymer microgels and their hybrids for environmental and catalytic applications.
Shuiqin Zhou received her BS (1988) and MS (1991) from Xiamen University, China, and her PhD (1996) from The Chinese University of Hong Kong. She received postdoctoral training at SUNY at Stony Brook and then worked at Union Carbide/The Dow Chemical Company as a senior chemist. She started her own research lab at The City University of New York at CSI in 2002 and is currently a professor of Chemistry at Department of Chemistry of College of Staten Island and Ph.D. Program in Chemistry, The City University of New York, 2800 Victory Boulevard, Staten Island, NY 10314, USA, working in field of gel-based nanomaterials for biosensing and smart drug delivery.
Robina Begum is an assistant professor at School of Chemistry, University of the Punjab, Lahore. She obtained her PhD degree in Chemistry from the same institute in 2019. She carried out a part of her research work in the laboratory of Prof. Jianliang Xiao at Department of Chemistry, University of Liverpool, UK as a split-site PhD scholar funded by Commonwealth Scholarship Commission, UK. Her research area is organic–inorganic hybrid materials for various applications.
Zahoor H. Farooqi is an associate professor at School of Chemistry, University of the Punjab, Lahore, Pakistan. He worked as a research associate in CSI, CUNY, New York, USA, from January 2009 to March 2010. In 2018, Dr. Farooqi worked for five months as a honorary research fellow in Department of Chemistry, University of Liverpool, UK, and from November 2022 to January 2023 as a visiting academic staff member in Department of Chemical Engineering, Loughborough University, UK. His area of research is microgels loaded with inorganic nanoparticles for catalytic applications.
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Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
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Research funding: Z. H. Farooqi and R. Begum are grateful to PU, Lahore, Pakistan, for a research grant for the period of 2022–2023. S. Zhou acknowledges research support from the NIDDK-NIH under award no. R15DK127360-01A1. A. Irfan is grateful to King Khalid University for financial support (RGP1/36/43).
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Conflict of interest statement: The authors declare that they have no conflicts of interest regarding this article.
Abbreviations
- 4-AP
-
4-Aminophenol
- 4-NP
-
4-Nitrophenol
- AA
-
acrylic acid
- AFS
-
atom force spectroscopy
- Ag NPs
-
silver nanoparticles
- Ag
-
silver
- AgNO3
-
silver nitrate
- AIBA
-
2,2′-Azobis(2-methylpropionamidene) dihydrochloride
- APBA
-
3-Aminophenylboronic acid
- APMA
-
N-(3-Aminopropyl)methacrylamide
- APS
-
ammonium persulphate
- Au NPs
-
gold nanoparticles
- Au
-
gold
- BIS
-
N,N′-methylenebisacrylamide
- BSA
-
bovine serum albumin
- CTA
-
cetyltrimethylammonium
- CTAB
-
cetyltrimethylammonium bromide
- DEAP
-
2, 2-diethoxyacetophenone
- D h
-
hydrodynamic diameter
- DHEA
-
N,N’-(1,2-dihydroxyethylene) bisacrylamide
- DLS
-
dynamic light scattering
- DTT
-
dithiothrietol
- DVB
-
divinylbenzene
- EDC
-
N-(3-dimethylaminopropyl)-N′-ethyl-carbodiimide hydrochloride
- EDX
-
energy-dispersive X-ray spectroscopy
- EGDMA
-
ethylene glycol dimethacrylate
- FESEM
-
field emission scanning electron microscopy
- FITC
-
fluorescein isothiocyanate
- FT-IR
-
fourier transmission-infrared spectroscopy
- HA
-
hyaluronic acid
- HAuCl4.3H2O
-
tetrachloroauric acid
- HCl
-
hydrochloric acid
- HEMA
-
hydroxyethylmethacrylate
- HF
-
hydrofluoric acid
- HsiM
-
hematite-silica microgel
- HSPs
-
hollow silica particles
- IA
-
itaconic acid
- KBH4
-
potassium borohydride
- KPS
-
potassium persulphate
- LBL
-
layer by layer
- LDH
-
lactate dehydrogenase
- MAA
-
methacrylic acid
- MMA
-
methylmethacrylate
- N2
-
nitrogen
- NaBH4
-
sodium borohydride
- NADH
-
nicotineamide dinucleotide
- NaIO4
-
sodium periodate
- NaOH
-
sodium hydroxide
- NIPAM
-
N-isopropylacrylamide
- NMR
-
nuclear magnetic resonance
- NPs
-
nanoparticles
- PAA
-
poly-acrylic acid
- Pb+2
-
lead ions
- PBA
-
phenylboronic acid
- PCS
-
photon correlation spectroscopy
- Pd
-
palladium
- PDMS
-
polydimethylsiloxane
- PEG
-
polyethylene glycol
- PGPR
-
polyglycerol polyricinoleate
- PLL
-
poly-L-lysine hydrobromide
- PMAA
-
poly(methacrylic acid)
- PNB
-
poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide)
- PNIPAM
-
poly(N-isopropylacrylamide)
- PNIPMAM
-
poly(N-isopropylmethacrylamide)
- PS
-
polystyrene
- Pt
-
platinum
- PVP
-
polyvinylpyrrolidone
- R h
-
hydrodynamic radius
- RHB
-
rhodamine B
- RS
-
Raman spectroscopy
- SANS
-
small angle neutron scattering spectroscopy
- SEM
-
scanning electron microscopy
- SiO2
-
silica
- SLS
-
static light scattering
- TEM
-
transmission electron microscopy
- TGA
-
Thermogravimetric analysis
- THF
-
tetrahydrofuran
- THSMGs
-
thermo-responsive hollow microgels
- TMSPMA
-
3-(trimethoxysilyl) propyl methacrylate
- UV
-
ultraviolet
- UV–vis
-
UV–visible spectroscopy
- VPT
-
volume phase transition
- VPTT
-
volume phase transition temperature
- XPS
-
X-ray photoelectron spectroscopy
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