Organic-inorganic hybrid nanoflowers: types, characteristics, and future prospects

Abstract

Organic-inorganic hybrid nanoflowers, a newly developed class of flower-like hybrid nanoparticles, have received much attention due to their simple synthesis, high efficiency, and enzyme stabilizing ability. This article covers, in detail, the types, structural features, mechanism of formation, and bio-related applications of hybrid nanoflowers. The five major types of hybrid nanoflowers are discussed, i.e., copper-protein, calcium-protein, and manganese-protein hybrid nanoflowers, copper-DNA hybrid nanoflowers, and capsular hybrid nanoflowers. The structural features of these nanoflowers, such as size, shape, and protein ratio generally determine their applications. Thus, the specific characteristics of hybrid nanoflowers are summarized in this review. The interfacial mechanism of nanoflower formation is examined in three steps: first, combination of metal ion and organic matter; second, formation of petals; third, growth of nanoflowers. The explanations provided herein can be utilized in the development of innovative approaches for the synthesis of hybrid nanoflowers for prospective development of a plethora of hybrid nanoflowers. The future prospects of hybrid nanoflowers in the biotechnology industry, medicine, sensing, and catalysis are also discussed.

Fig. 1

Application cycle of the membrane with incorporated laccase nanoflowers: fabrication, use, rinse, and reuse. Phenol and ortho-, meta-, and para-substituted phenols react with 4-aminoantipyrine to form colored compounds, which can be easily detected. Reproduced with permission from Ref. [36]: Copyright 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Fig. 2

The cascade enzymatic reaction of multi-enzyme co-embedded hybrid nanoflower for glucose detection. Reproduced with permission from Ref. [37]: Copyright 2014, Royal Society of Chemistry

Fig. 3

a Allosteric effect of α-amylase: α-amylase changes from inactive form to active form by binding calcium ion to allosteric site in inactive α-amylase and b α-amylase immobilized in nanocrystals. Reproduced with permission from Ref. [44]: Copyright 2013, American Chemical Society

Fig. 4

Schematic synthesis of chitosan–calcium ion hybrid nanoflower. Chitosan binds to pyrophosphate through ionotropic gelation and generates CS-TPP gel complex which reacts with calcium phosphate crystal to form hybrid nanoflower. Reproduced with permission from Ref. [45]: Copyright 2014, American Chemical Society

Fig. 5

Schematic representation of the synthesis of manganese-based hybrid nanoflowers as a novel electrochemical biosensor for the detection of ractopamine, including (i) Mn₃(PO₄)₂-IgG, (ii) Mn₃(PO₄)₂-RAC_anti (anti-ractopamine antibody), and (iii) Mn₃(PO₄)₂-BSA-Au nanoflowers. Reproduced with permission from Ref. [46]: Copyright 2015, Elsevier

Fig. 6

Sequence-independent self-assembly of multicolor FRET (fluorescence resonance energy transfer) DNA hybrid nanoflower. Reproduced with permission from Ref. [55]: Copyright 2014, Wiley-VCH Verlag

Fig. 7

Scheme of preparation procedure of the FPSH capsules: a formation of protein–inorganic hybrid microflowers; b formation of (protamine-silica)₂ bilayers on the microflowers; c formation of the FPSH capsules after eliminating the microflower template through EDTA treatment. Reproduced with permission from Ref. [56]: Copyright 2014, The Royal Society of Chemistry

Fig. 8

Synthesis mechanism of organic–inorganic hybrid nanoflower. Reproduced with permission from Ref. [35]: Copyright 2012, Nature Publishing Group