Research progress on large‐pore mesoporous silica nanoparticles

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Research progress on large‐pore mesoporous silica nanoparticles

Journal Title: China Powder Science and Technology - Year 2025, Vol 31, Issue 2

Abstract

[Significance] Since the pioneering work in 2001 on the synthesis of mesoporous silica nanoparticles （MSNs） by employing a modified cationic surfactant templating route under suitable conditions， such as dilute solution and high temperatures， MSNs have attracted significant attention due to their tunable particle sizes， morphologies， misstructures， high surface areas， hydrophilic and easily functionalized surfaces， and biocompatibility. These structural or morphological properties have made MSNs appealing for diverse applications， including drug delivery， imaging， catalysis， and sensing. In biomedical areas， monodisperse MSNs in the 50~200 nm size range with large mesopores are especially desirable， as these facilitate cell uptake and biomolecule encapsulation. In addition， the accessible internal surface area and pore volume resulting from interconnected pores would be especially advantageous for these applications. Large-pore MSNs （LPMSNs）， characterized by nano-scale particle sizes， large mesopores， and high surface areas， have attracted tremendous scientific and technological interest due to their high potential in adsorption， catalysis， and support systems. The review focuses on the research progress of LPMSNs， especially on synthesis techniques and mechanisms for achieving large mesopores， with the aim of supporting future LPMSNs research and development. [Progress] LPMSNs with tunable structures （e.g.， ordered， disordered， dendritic） and mesopore sizes （5~50 nm） exhibit properties suitable for various applications， such as high adsorption capacity， high catalytic efficiency， and enhanced mass transfer. So far， several methods have been developed to prepare LPMSNs， using composite templates， high molecular weight organic templates， or organic pore-swelling agents， through direct or post-synthetic approaches. Although these methods produce desirable structures， they also have drawbacks. For example， multiple templates can produce ordered mesostructures with tunable large mesopores， but they often rely on specialized or expensive templates， which might impede large-scale production. Organic swelling agents （OSAs） are effective for enlarging mesopores， but their high consumption and potential toxicity might pose great challenges on green and low-cost production of LPMSNs. Additionally， certain organic molecules or aggregates can guide LP-MSNs synthesis， though their availability and cost may limit their practical application. Recently， post-treatment methods using inorganic acids （e.g.， sulfuric or boric acid） or salts （e.g.， ammonium chloride， sodium tetrahydroborate） have been demonstrated to be able to effectively enlarge mesopores up to tens of nanometers in conventional small-mesopore MSNs， while maintaining surface areas of up to 300 m2/g. These methods， based on the Ostwald ripening process， are simpler and more cost-effective than OSA-based methods. However， It is worth noting that conducting Ostwald ripening process under harsh conditions （e.g.， high temperatures over 140 oC for extended periods） can significantly deteriorate mesostructures， leading to a substantial drop in surface area. Therefore， a balance must be struck between achieving ultra-large mesopores （e.g.， over 20 nm） and maintaining sufficient surface area. Conclusions and Perspective　Future research should focus on the green synthesis of LPMSNs with tunable structures to enhance performance. For LPMSNs synthesis， it is suggested that future research should prioritize the following topics： 1） developing LPMSNs with novel structures for current and emerging applications， including hollow or hierarchically porous LPMSNs； 2） exploring low-cost and eco-friendly templates to reduce production costs and pollution； and 3） improving synthesis efficiency by increasing SiO2 solid content in the mixture， aiming for high-solid content synthesis approaches that maintain both the structure and dispersibility of LPMSNs. Reducing production costs necessitates the use of affordable silica sources. Low-cost LPMSNs with high surface area and good dispersibility could greatly extend their applications to replace fumed silica or xerogels in fields like food， composite additives， and paints. Overall， LPMSNs hold significant potential in applications demanding high loading capacities for biomolecules， drugs， and enzymes. They can be used as supports for catalysis with enhanced mass transfer， and as efficient adsorbents and useful additives.

Authors and Affiliations

Wei WANG, Haodong SUN, Rui SUN

Keywords

EP ID EP760568
DOI 10.13732/j.issn.1008-5548.2025.02.003
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