Evaluation of Shear Horizontal Surface Acoustic Wave Biosensors Using “Layer Parameter” Obtained from Sensor Responses during Immunoreaction

Shear horizontal surface acoustic wave (SH-SAW) biosensors measure the reaction of capture antibodies immobilized on the sensing surface to capture test molecules (antigens) by using the change in SH-SAW propagation characteristics. SH-SAW displacement exists not only on the SH-SAW propagating surface, but also partially penetrates the specimen liquid to a certain depth, which is determined by the liquid properties of the specimen and the operating frequency of the SH-SAW. This phenomenon is called viscosity penetration. In previous studies, the effect of viscosity penetration was not considered in the measurement of SH-SAW biosensors, and the mass or viscosity change caused by the specific binding of capture antibodies to the target antigen was mainly used for the measurement. However, by considering the effect of viscosity penetration, it was found that the antigen–antibody reaction could be measured and the detection characteristics of the biosensor could be improved. Therefore, this study aims to evaluate the detection properties of SH-SAW biosensors in the surface height direction by investigating the relationship between molecular dimensions and SH-SAW propagation characteristics, which are pseudo-changed by varying the diameter of gold nanoparticles. For the evaluation, we introduced a layer parameter defined by the ratio of the SH-SAW amplitude change to the SH-SAW velocity change caused by the antigen–antibody reaction. We found a correlation between the layer parameter and pseudo-varied molecular dimensions. The results suggest that SH-SAW does not only measure the mass and viscosity but can also measure the size of the molecule to be detected. This shows that SH-SAW biosensors can be used for advanced functionality.

The Effect of Cladode Drying Techniques on the Prebiotic Potential and Molecular Characteristics of the Mucilage Extracted from Opuntia ficus-indica and Opuntia joconostle

The dry, powdered cladodes of Opuntia ficus-indica are often-used in over-the-counter (OTC) pharmaceutical formulations. Gentle drying techniques, such as lyophilization and vacuum drying are compared with convection drying for the cladodes and also compared with another species of economic importance, Opuntia joconostle. The heteropolysaccharide purified from the mucilage extracted from the dried powders were investigated in their monosaccharide composition (HPAEC-PAD, TLC), mineral and protein content, molecular dimensions (SEC) and fermentability by probiotic bacteria (Bioscreen technique) for evaluation of the prebiotic potential of the mucilage. The heteropolysaccharide is composed of galactose, arabinose, xylose, galacturonic acid and rhamnose. O. ficus-indica includes an additional 13% of glucose coming from an α-glucan. The content of Ca (0.3%) and Mg (0.4%) is relatively low in both species; the content of protein adds up to 1.5% in O. ficus-indica but is significantly lower in O. joconostle with 0.8%. The average molecular mass Mw of the extracted mucilage ranges from 3.7 to 4.7 × 105 g∙mol−1 for both species; only the mucilage from long-time convection drying (C2) delivers a lower average Mw of 2.6 × 105 g∙mol−1, due to partial breakdown of the mucilage matrix. All tested probiotic strains utilized the mucilage to some extent; C2 being the most active, and thus confirms the prebiotic potential of cladode’s powder and its derived products. In general, the molecular dimensions and prebiotic potential are not extremely sensitive to the drying treatment, yet temperature and drying time can modify the cladode’s powder to a profile with better prebiotic characteristics.

Structure and 3D-3D Topotactic Transformation of the Aluminophosphate Molecular Sieve PST-5 and Its Implication in New Zeolite Structure Generation

Zeolites have attracted great interest over recent decades. Their unique pore structures of molecular dimensions and tunable compositions make them ideal for shape selective catalysis and separation. However, targeted synthesis of zeolites with new pore structures and compositions remains a key challenge. Here, we propose a novel approach based on a unique 3D-3D topotactic transformation, which takes advantage of weak bonding in zeolites. This is inspired by the structure transformation of PST-5, a new aluminophosphate molecular sieve, to PST-6 by calcination at 500 °C. The structure of PST-5 was determined from micrometer-sized crystals by 3D electron diffraction (3DED, also known as MicroED). We found that the 3D-3D topotactic transformation involves two types of building units where penta- or hexa-coordinated Al is present. We applied this approach to several other zeolite systems and predicted a series of new zeolite structures that would be synthetically feasible. This method provides a new concept for the synthesis of targeted zeolites, especially those which may not be feasible by conventional methods.

Structure and 3D-3D Topotactic Transformation of the Aluminophosphate Molecular Sieve PST-5 and Its Implication in New Zeolite Structure Generation

Zeolites have attracted great interest over recent decades. Their unique pore structures of molecular dimensions and tunable compositions make them ideal for shape selective catalysis and separation. However, targeted synthesis of zeolites with new pore structures and compositions remains a key challenge. Here, we propose a novel approach based on a unique 3D-3D topotactic transformation, which takes advantage of weak bonding in zeolites. This is inspired by the structure transformation of PST-5, a new aluminophosphate molecular sieve, to PST-6 by calcination at 500 °C. The structure of PST-5 was determined from micrometer-sized crystals by 3D electron diffraction (3DED, also known as MicroED). We found that the 3D-3D topotactic transformation involves two types of building units where penta- or hexa-coordinated Al is present. We applied this approach to several other zeolite systems and predicted a series of new zeolite structures that would be synthetically feasible. This method provides a new concept for the synthesis of targeted zeolites, especially those which may not be feasible by conventional methods.

Structure and 3D-3D Topotactic Transformation of the Aluminophosphate Molecular Sieve PST-5 and Its Implication in New Zeolite Structure Generation

Zeolites have attracted great interest over recent decades. Their unique pore structures of molecular dimensions and tunable compositions make them ideal for shape selective catalysis and separation. However, targeted synthesis of zeolites with new pore structures and compositions remains a key challenge. Here, we propose a novel approach based on a unique 3D-3D topotactic transformation, which takes advantage of weak bonding in zeolites. This is inspired by the structure transformation of PST-5, a new aluminophosphate molecular sieve, to PST-6 by calcination at 500 °C. The structure of PST-5 was determined from micrometer-sized crystals by 3D electron diffraction (3DED, also known as MicroED). We found that the 3D-3D topotactic transformation involves two types of building units where penta- or hexa-coordinated Al is present. We applied this approach to several other zeolite systems and predicted a series of new zeolite structures that would be synthetically feasible. This method provides a new concept for the synthesis of targeted zeolites, especially those which may not be feasible by conventional methods.

Structure and 3D-3D Topotactic Transformation of the Aluminophosphate Molecular Sieve PST-5 and Its Implication in New Zeolite Structure Generation

Zeolites have attracted great interest over recent decades. Their unique pore structures of molecular dimensions and tunable compositions make them ideal for shape selective catalysis and separation. However, targeted synthesis of zeolites with new pore structures and compositions remains a key challenge. Here, we propose a novel approach based on a unique 3D-3D topotactic transformation, which takes advantage of weak bonding in zeolites. This is inspired by the structure transformation of PST-5, a new aluminophosphate molecular sieve, to PST-6 by calcination at 500 °C. The structure of PST-5 was determined from micrometer-sized crystals by 3D electron diffraction (3DED, also known as MicroED). We found that the 3D-3D topotactic transformation involves two types of building units where penta- or hexa-coordinated Al is present. We applied this approach to several other zeolite systems and predicted a series of new zeolite structures that would be synthetically feasible. This method provides a new concept for the synthesis of targeted zeolites, especially those which may not be feasible by conventional methods.