Mesoporous Silica As a Sensing Material

Ordered mesoporous silica materials have unique morphological properties and adjustable physical and chemical properties. These features enable them to be used as carriers for macromolecules and drug molecules.

We immobilised diphenylthiocarbazone (DZ) dye into 2D hexagonal MCM-41 and 3D cubic Fd3m HOM-11 mesoporous silica microscopic monoliths. The resulting absorption-based sensor possesses high sensitivity and selectivity to detect organophosphorus trace-level vapor.

Surface Functionalization

Mesoporous silica is a promising material for many applications, including sensing. Its tunable pore size, easily modifiable surface properties, and large surface area make it an attractive substrate for sensor development. However, high sensitivity and selectivity are required for practical application. This requires the modification of mesoporous silica with diverse functional groups and materials, as well as the assembly of heterostructured MSMs.

Ordered mesoporous silica (OMS) matrices have unique structural and physical properties that make them ideal for use in electroanalytical sensors, such as capacitive and resistive gas sensors. These mesoporous structures have uniform pore sizes, large surface areas and good chemical stability. They also provide excellent accessibility to the active sites, making them a suitable platform for sensing applications requiring specific interaction with organic molecules and ions.

In recent years, several template-assisted methods have been developed to produce mesoporous OMS materials with well-defined and uniform pore systems. These structures can be functionalized with diverse groups, including amines, carboxylic acids, hydrophobic molecules and polymers. The resulting modified mesoporous silica has been successfully employed as the active layer in sensor devices with operating principles based on capacitive, resistive and optical detection.

In addition to their ability for drug delivery, mesoporous silica nanomaterials have been used as scaffolds for bone tissue engineering. Bone tissue engineering involves the replacement of missing or damaged bone cells to promote and stimulate bone growth. It is crucial for skeletal health and the repair of fractures. The use of mesoporous SNMs for this purpose can enable the rapid and safe delivery of growth factors and medicinal drugs to bone cells. Moreover, you may visit nearest mesoporous silica supplier to get mor information.

Fluorescence Imaging

In order to facilitate the detection of cations, molecules and heavy metals, mesoporous silica can be incorporated with dyes which can absorb or fluoresce upon binding with the respective target. This allows for optical detection and measurement methods to be employed which can provide faster, more sensitive, and simpler than classical instrumental techniques. Mesoporous silica materials can be fabricated in a variety of shapes and geometries to suit the sensing applications.

Moreover, mesoporous silica exhibits unique features that make it a promising substrate for electroanalytical sensors and electrocatalysis. These include uniform pore sizes, very high specific surface areas (typically exceeding 1000 m2 g-1), and long-range ordering of the packing of pores. In addition, mesoporous silica is able to be easily functionalized with organic groups that are useful in enhancing sensor performance and sensitivity.

The synthesis of ordered mesoporous silica with controlled porosity, pore geometry and morphology has been made possible by nanotemplating techniques [1]. The resulting materials have been shown to be excellent active layers for gas sensors based on capacitive, resistive and other operating principles.

In particular, mesoporous silica-based materials with uniform and ordered pore structures have demonstrated excellent performance in the determination of heavy metal ions. This is primarily because the high porosity, exceptional adsorption capacity, and tuneable 3D shape and geometry of the resulting material can significantly enhance the limits of detection and response time of the corresponding sensor.

Nanoparticles for Drug Delivery

In drug delivery applications, mesoporous silica nanoparticles can be incorporated to deliver drugs, genetic material, and other biomaterials to specific targets in the body. Drugs can be delivered to tumors, cells within a cancerous tumour, or to other tissues that need treatment without damaging the surrounding healthy tissue. The drug can be released at a slow rate to sustain the therapeutic effect. These drug-delivery systems can also evade the body’s protection mechanisms by incorporating surface modifications to avoid being recognized and eliminated by immune cells.

Mesoporous silica materials can be used to build chemical and optical sensors for monitoring the presence of ions and molecules in environmental samples. The pore features and geometry of mesoporous silica can be tuned to improve the limit of detection and response time of the sensor. This is particularly important when the sensor needs to respond rapidly to changes in conditions such as humidity, light intensity, or ionic concentrations.

Other sensor uses for mesoporous silica include the detection of bacteria, viruses, and the pH of liquids. The reversible nature of the mesoporous silica allows the indicator to be removed, and the sensor can be reused after each use. Another useful technique is the formation of a pH subtle drug delivery system that utilizes mesoporous silica to transport DNA or mRNA sequences that mimic disease antigens. The sequences are then copied by the cells to produce proteins that arouse an immune response against the disease.

A mesoporous silica-based microparticle is being developed to carry folic acid across the blood-brain barrier and into the brain in order to treat Alzheimer’s disease. The microparticles are surrounded by a pH-sensitive coating that releases the folic acid when the target cells are present. The system can be modified to encapsulate other biomaterials that can be targeted to the brain or other organs.

Biomedical Applications

Ordered mesoporous silica has a wide range of applications as an advanced sensing material. Its unique pore volume, controlled morphology and size, stability over a wide pH range and chemical, mechanical, and thermal properties, transparency in the visible region of the spectrum, and silane chemistry allow for functionalization to covalently attach various molecular probes on its surface.
This is a key factor for developing highly sensitive, targeted, and specific sensing devices. Several humidity sensors, such as resistive, impedance, cantilever, SAW, and quartz crystal microbalance (QCM) have been developed based on mesoporous silica with different pore structures, geometry, and morphology.

Mesoporous silica-based imprinted sensor arrays for heavy metal cation detection have been constructed. The imprinted mesoporous silica MCM-41 exhibited excellent fluorescence response towards Zn2+ and Cd2+. The sensing data was validated by high-resolution scanning electron microscopy, atomic force microscopy, and flourier transform infrared spectroscopy.