CommentaryIntroduction to nanocoatings produced by layer-by-layer (LbL) self-assembly☆
Graphical abstract
Section snippets
Historical perspective on layer-by-layer self-assembly
Novel materials have always been sought and the employment of surface modification at the molecular level realized this goal. Surface modification resulted in a multitude of new properties that were previously not associated with the native material. These changes include modifications of the electrical, optical, magnetic, physicochemical and biological properties of the material in question. As a consequence, several disciplines of natural science have experienced the impact of surface
Basic principles of the layer-by-layer technique
The formation of nanocoatings using LbL self-assembly technique distinguishes itself in its simplicity from other surface modification methods such as spin-coating, solution casting, thermal deposition, chemical self-assembly and the LB technique and will be discussed next.
Coating materials and substrates
Several polyelectrolytes and nanoparticles can be utilized to form the ultrathin multilayer structures using the LbL self-assembly technique. Furthermore, several substrates can be coated with nanothin multilayers.
Experimental parameters and LbL adsorption
The formation of polyelectrolyte multilayer self-assembly is usually reliant on the electrostatic adsorption between the substrate and subsequent layers [14], [53]. A two-stage process is envisioned by which (1) an initial anchoring of the coating material to the surface is followed by (2) a slow relaxation to form a densely-packed structure on the surface [89]. Some processing parameters that influence the adsorption steps of LbL assembly are briefly discussed.
Layer-by-layer disassembly
In several cases, intact LbL constructed systems are required to remain stable in order to control the release of substances i.e. drugs [42], [44] by posing a barrier to release with the possibility of variation of barrier permeability for water-soluble drugs and dyes substances under the influence of external stimuli such as changes in temperature or ultrasonic treatment [123].
The alternative approach to release the captured content in an LbL-assembled system relies on the disassembly of the
Characterization of LbL constructs
The combination of several techniques can be used to study the construction, disassembly or release of captured content from LbL PEMs. Some of the more common methods will be briefly discussed (Fig. 3).
Advantages of LbL-assembled multilayers
LbL self-assembly offers several advantages to other methods of encapsulation, coating or fixation of substances: (1) the wall thickness of capsules can be tailored in the nm–μm range, (2) several types of synthetic/natural colloids are available for LbL, (3) the location and sequence of the layers can be controlled, (4) surface labeling with targeting molecules is possible, (5) stabilization of submicron particles is possible [167], (6) LbL avoids the use of thermodynamically unstable
Conclusions
The evolvement and simplicity of LbL construction provided a simple, robust platform, independent of precise stoichiometry, for the modification of material surfaces or the encapsulation of various substrates. The technique facilitated a ‘library’ approach to create novel carrier systems, especially in the field of drug delivery. A myriad of colloids can be used to create novel hybrid-coated materials by use of different intermolecular forces.
Multifunctionality of LbL systems can be introduced
References (218)
Interaction of chromophores in monolayer assemblies
Pure Appl. Chem.
(1971)Multilayers of colloidal particles
J. Colloid Interface Sci.
(1966)Deposition of thin solid compound films by a successive ionic-layer adsorption and reaction process
Appl. Surf. Sci.
(1985)- et al.
Solution growth of ZnS, CdS and Zn1−xCdxS thin films by the successive ionic-layer adsorption and reaction process, growth mechanism
J. Cryst. Growth
(1988) - et al.
Polyaniline, polypyrrole, poly(3-methylthiophene) and polybitiophene layer-by-layer deposited thin films
Synth. Met.
(1991) - et al.
Buildup of ultrathin multilayer films by self-assembly process: III. Consecutively alternating adsorption of anionic and cationic polyelectrolytes on charged surfaces
Thin Solid Films
(1992) - et al.
Fabrication of poly(p-phenylene vinylene) (PPV) nanoheterocomposite films via layer-by-layer adsorption
Supramol. Sci.
(1995) - et al.
X-ray analysis of ultrathin polymer films self-assembled onto substrates
Physics B (Amsterdam, Neth.)
(1994) - et al.
Assembly of polyelectrolyte films by consecutively alternating adsorption of polynucleotides and polycations
Thin Solid Films
(1996) - et al.
Multifunctional cargo systems for biotechnology
Trends Biotechnol.
(2007)
Multilayer films consisted of azulene-based dye molecules and polyelectrolyte: preparation, characterization and photoluminescent property
Thin Solid Films.
Low-cost, transparent, and flexible single-walled carbon nanotube nanocomposite based ion-sensitive field-effect transistors for pH/glucose sensing
Biosens. Bioelectron.
Engineered microcrystals for direct surface modification with layer-by-layer technique for optimized dissolution
Eur. J. Pharm. Biopharm.
Islet-encapsulation in ultra-thin layer-by-layer membranes of poly(vinyl alcohol) anchored to poly(ethylene glycol)-lipids in the cell membrane
Biomaterials
Layer by layer chitosan/alginate coatings on poly(lactide-co-glycolide) nanoparticles for antifouling protection and folic acid binding to achieve selective cell targeting
J. Colloid Interface Sci.
Layer-by-layer self-assembly: the contribution of hydrophobic interactions
Nanostruct. Mater.
A careful examination of the adsorption step in the alternate layer-by-layer assembly of linear polyanion and polycation
Colloids Surf. A
Polysaccharide-protein surface modification of titanium via a layer-by-layer technique: characterization and cell behaviour aspects
Biomaterials
New nanocomposite films for biosensors: layer-by-layer adsorbed films of polyelectrolytes, proteins or DNA
Biosens. Bioelectron.
Visco-and adhesive properties of adsorbed polyelectrolyte multilayers determined in situ with QCM-D and AFM measurements
J. Colloid Interface Sci.
Absorption of polyelectrolytes on colloidal surfaces as studied by electrophoretic and dynamic light-scattering techniques
J. Colloid Interface Sci.
Of the stilling of waves by means of oil. Extracted from sundry letters between Benjamin Franklin, L.L.D. F.R.S. William Brownrigg, M.D. F.R.S. and the Reverend Mr. Farish
Philos. Trans. R. Soc. Lond. A
Measurement of the amount of oil necessary in the order to check the motions of camphor upon water
Proc. R. Soc. Lond.
Surface tension
Nature (London)
XXXVI. Investigations in capillarity: the size of drops. The liberation of gas from supersaturated solutions. Colliding jets. The tension of contaminated water surfaces
Philos. Mag.
The constitution and fundamental properties of solids and liquids. II. Liquid
J. Am. Chem. Soc.
The mechanism of the surface phenomena of flotation
Trans. Faraday Soc.
The properties and molecular structure of thin films of palmitic acid on water. Part I
Proc. R. Soc. Lond. A Math. Phys. Sci.
Films built by depositing successive monomolecular layers on a solid surface
J. Am. Chem. Soc.
Activities of urease and pepsin monolayers
J. Am. Chem. Soc.
Built-up films of barium stearate and their optical properties
Phys. Rev.
Langmuir-Blodgett Films
Science
Systems of monomolecular layers—assembling and physicochemical behavior
Angew. Chem. Int. Ed.
Electronic Properties of Conjugated Polymers III
Assembly of multicomponent protein films by means of electrostatic layer-by-layer adsorption
J. Am. Chem. Soc.
Molecular-level processing of conjugated polymers. 4. Layer-by-layer manipulation of polyaniline via hydrogen-bonding interactions
Macromolecules
A new approach for the fabrication of an alternating multilayer film of poly(4-vinylpyridine) and poly(acrylic acid) based on hydrogen bonding
Macromol. Rapid Commun.
Buildup of polymer/Au nanoparticle multilayer thin films based on hydrogen bonding
Chem. Mater.
Investigation into an alternating multilayer film of poly(4-vinylpyridine) and poly(acrylic acid) based on hydrogen
Langmuir
Applying polymer chemistry to interfaces: layer-by-layer and spontaneous growth of covalently bound multilayers
Langmuir
Thermoresponsive ultrathin hydrogels prepared by sequential chemical reactions
Macromolecules
Click chemistry: diverse chemical function from a few good reactions
Angew. Chem. Int. Ed.
Multi-functional polymeric nanoparticles for tumour-targeted drug delivery
Expert Opin. Drug Deliv.
Multifunctional layer-by-layer carbon nanotube-polyelectrolyte thin films for strain and corrosion sensing
Smart Mater. Struct.
Stimuli-responsive multilayered hybrid nanoparticles/polyelectrolyte capsules
Macromol. Rapid Commun.
Novel encapsulated functional dye particles based on alternately adsorbed multilayers of active oppositely charged macromolecular species
Macromol. Rapid Commun.
Characterization and biocompatibility studies of novel humic acids based films as membrane materials for an implantable glucose sensor
Biomacromolecules
Layer-by-layer construction of an active multilayer enzyme electrode applicable for direct amperometric determination of cholesterol
Sens. Actuators B
Controlled layer-by-layer immobilization of horseradish peroxidase
Biotechnol. Bioeng.
Spontaneous deposition of horseradish peroxidise into polyelectrolyte multilayer capsules to improve its activity and stability
Chem. Commun.
Cited by (321)
pH stimulus-responsive hybrid nanoparticles: A system designed for follicular delivery of brazilian plant-derived 5-alpha-reductase enzyme inhibitors
2024, International Journal of PharmaceuticsRobust, versatile, green and emerging Layer-by-Layer Self-Assembly platform for solar energy conversion
2023, Coordination Chemistry ReviewsAnti-fouling electrospun organic and inorganic nanofiber membranes for wastewater treatment
2023, South African Journal of Chemical Engineering
- ☆
This commentary is part of the Advanced Drug Delivery Reviews theme issue on “Layer-by-Layer Self-Assembled Nanoshells for Drug Delivery”.