Luminescent Transparent Composite Films Based on Lanthanopolyoxometalates and Filmogenic Polysaccharides

Abstract

A series of polysaccharide-based transparent composite films containing lanthanopolyoxometalates (LnPOMs) have been prepared by using a water-soluble cationic chitosan derivative [HTCC = N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride] and pullulan (PUL). HTCC was more suitable than pure chitosan for this purpose due to its positive charge and solubility in water over a broad range of pH values. The LnPOMs [Ln(W 5 O 18 ) 2 ] 9-(Ln = Eu and Tb) were incorporated into the polysaccharides. EuPOMs encapsulated in amorphous silica shells were also incorporated into the [a]

Natural Polymers-Based Materials: A Contribution to a Greener Future

“…Engineering natural polymers-based materials derived from polysaccharides and proteins is the main objective of the work carried out by the BioPol4fun research group. In the last decade, we have been intensively exploiting cellulose [ 63 , 64 ], nanocelluloses (e.g., bacterial nanocellulose (BNC) [ 61 , 65 , 66 ], nanofibrillated cellulose (CNFs) [ 67 , 68 ] and cellulose nanocrystals (CNCs) [ 69 ]), chitosan [ 70 , 71 , 72 , 73 ], pullulan [ 71 , 74 , 75 , 76 ], starch [ 68 ], hyaluronic acid [ 77 , 78 ], alginate [ 79 ], fucoidan [ 80 , 81 ], agar [ 82 ], lysozyme [ 83 , 84 , 85 , 86 ], and gelatin [ 87 ] ( Figure 1 ) to fabricate films [ 85 , 88 , 89 , 90 , 91 ], membranes [ 81 , 92 , 93 , 94 , 95 ], (nano)composites reference [ 64 , 96 , 97 , 98 , 99 ], coatings [ 100 , 101 , 102 , 103 ], nanosystems [ …”

“…Apart from cellulosic substrates, several other polymeric feedstocks of natural origin have been the object of study by our group ( Figure 1 ), in particular polysaccharides derived from marine sources (e.g., chitosan [ 68 , 71 , 72 , 73 , 74 , 90 , 91 , 102 , 103 , 129 ], fucoidan [ 80 ], and agar [ 82 ]) and microorganisms (e.g., pullulan [ 71 , 74 , 75 , 76 , 99 , 108 , 130 , 131 ]), and also some proteins, such as gelatin [ 87 ] and lysozyme [ 108 , 131 ] ( Table 2 ). Most of the works deal with the direct shaping of these raw materials into films [ 71 , 72 , 74 , 75 , 82 , 90 , 91 , 108 , 130 , 131 ]; however, the design of nanocomposites [ 68 , 99 , 129 ], coatings [ 73 , 102 , 103 ], nanosystems [ 80 ], and microneedles [ 76 , 87 ] is also described for the above-mentioned natural feedstocks.…”

“…Attending to the high filmogenic abilities of polysaccharides such as chitosan and pullulan [ 20 , 132 ], films [ 71 , 72 , 74 , 75 , 82 , 90 , 91 , 108 , 130 , 131 ], and composite films [ 68 , 129 ] can be easily obtained via the solvent casting technique. The inclusion of compounds of interest (e.g., metallic nanoparticles [ 129 , 130 ], (nano)fibers [ 68 , 99 , 108 , 131 ] and bioactive compounds [ 75 , 82 , 90 ]) is achieved by direct dispersion or dissolution in the polymer solution before casting.…”

Cation‐Directed Dimeric versus Tetrameric Assemblies of Lanthanide‐Stabilized Dilacunary Keggin Tungstogermanates

“…For example, [Eu(W 5 O 18 ) 2 ] 9À has been incorporated to multi-wavelength core/shell nanoparticles and Langmuir-Blodgett or layer-by-layer thin films that contain different types of matrices (e.g., surfactants, agarose, polysaccharides, layered double hydroxides) and show color tuning or chemically controlled switching of the emission. [11] A few years ago, some of us reported the serendipitous isolation of the [K&K 7 Ce III 24 Ge 12 W 120 O 456 (OH) 12 (H 2 O) 64 ] 52À crown-shaped POM from a one-pot reaction of WO 4 2À , Ce 3 + , and GeO 2 with K + ions as template. [12] This dodecameric assembly is made up of three different types of dilacunary Keggin subunits stabilized by cerium coordination onto the vacant sites.…”

Raman and Fluorescence Imaging of Polyoxometalate Composite Agarose Films

“…Lanthanopolyoxometalate (LnPOM) containing nanocomposites have been investigated in our group to explore the optical properties. Luminescent transparent composite films based on LnPOMs and filmogenic polysaccharides have been prepared by us, using pullulan and a water‐soluble cationic chitosan derivative . Thermosensitive polysaccharides such as carrageenan hydrogels have also been used in the preparation of LnPOM composites .…”