Table 1.

Examples of Various Nanoarchitecting Approaches toward Tuning the Stable Siliceous Frameworks

Type of Tuning		Precursors	Particle Size (nm)	Outcome/Benefits	References
Molecular integration	Periodic mesoporous organosilicas (PMOs)	Benzene, ethylene, ethane, 2,2′-bipyridine, thiophene, divinylbenzene, biphenyl, bis-imidazolium, among others	20–500 nm	These organo-inorganic hybrid composites offer improved compatibility, degradability, and chemical, electronic, mechanical, magnetic, as well as optical properties.	(Asefa et al., 1999; Cho et al., 2009; Croissant et al., 2014a, 2014b, 2016a; Dinker and Kulkarni, 2016; Du et al., 2016; Grosch et al., 2015; Inagaki et al., 1999; Maegawa and Inagaki, 2015; Sayari and Wang, 2005)
	Disulfide-bridged constructs	Bis (triethoxysilyl propyl) disulfide, (- (CH2)3-S ∼ S- (CH2)3-)	20–350	Enhanced GSH-triggered biodegradation through a disulfide-thiol exchange reaction.	(Croissant et al., 2014a; Du et al., 2018b; Kim et al., 2012; Quesada et al., 2013; Teng et al., 2014; Zhang et al., 2003; Zhou et al., 2017)
		Bis (triethoxysilyl propyl)tetrasulfide (- (CH2)3-S ∼ S ∼ S ∼ S- (CH2)3-)	30–2000	-do-	(Wu et al., 2015; Yang et al., 2016b)
	Diselenide-bridged constructs	Se-Se	∼50 nm	Rapid GSH-triggered biodegradation over the disulfide linkage due to weaker electronegativity.	(Shao et al., 2018)
	Metal-impregnated mesoporous silicas	Al	–	Incorporated Al species (Al-MCM-41/Al-MCM-48) enhanced the acidity for catalysis applications.	(Aspromonte et al., 2012; Cesteros and Haller, 2001; Chen et al., 1993; Corma et al., 1994; Eimer et al., 2002; Huo et al., 2014; Kolodziejski et al., 1993; Monnier et al., 1993; Ryoo et al., 1997)
		Cu	∼100	Offered pH-responsive release and degradation of MSNs.	(Kankala et al., 2015, 2017, 2020b; Kuthati et al., 2017; Liu et al., 2019)
		Fe	50–150	Facilitated the unique chemical coordination-accelerated biodegradation.	(Wang et al., 2017)
		Co, Fe, Ni	–	Influenced the adsorption capacity, activity, and stability of the catalysts.	(Parvulescu and Su, 2001)
		Zn	∼100	Offered pH-responsive release of therapeutic guests in MSNs.	(Kankala et al., 2020a, 2020c)
Shaping	Janus-type architectures	Gold, platinum, upconverting nanoparticles (UCNPs), iron oxide, and first-row-transition metal species	30–300	Metal-associated asymmetric shaped constructs with well-defined particle sizes showed improved magnetic, electrical, and optical, as well as mobility characteristics.	(Abbaraju et al., 2017; Karimi et al., 2017; Li et al., 2014; Liu et al., 2019; Ma et al., 2015; Shao et al., 2016; Ujiie et al., 2015; Villalonga et al., 2013; Wang et al., 2019c; Xuan et al., 2016)
	Multi-podal/multi-compartment architectures	Ethyl acetate, mixed organosilane precursors	100–200	Multi-compartment nanocontainers offered selective drug adsorption for multidrug delivery.	(Croissant et al., 2015a; Suteewong et al., 2013; Zhao et al., 2019)
	Flower-shaped packing/dendritic/radially porous designs	Adding cosolvents (diethyl ether, pentanol) and utilizing catalysts (triethanolamine, reduced ammonia), 4-mercaptophenylacetic acid, poly (acrylic acid), and altered emulsion components ratio	50–200	Center-wide radial porous channels offered improved encapsulation of large-sized therapeutic molecules.	(Das et al., 2019; Du and Qiao, 2015; Gao et al., 2017; Wang et al., 2013, 2019a, 2019b; Xu et al., 2015; Zheng et al., 2018)
Dynamic modulation	Deformable solids	PMO (thioether/benzene/ethane-bridged)-based siliceous shells	50–200	Enriched the cellular internalization by changing their overall morphology (spherical-to-oval) during the mechanical inner stress.	(Teng et al., 2018)