Size‐Transformable Nanostructures: From Design to Biomedical Applications

Abstract

AuNPs) with a size of 50 nm were more easily internalized into mammalian cells than were AuNPs of other sizes (14, 30, 74, and 100 nm). [3] Jiang et al. demonstrated that gold and silver nanoparticlemediated cellular responses were size dependent. [4] Wang et al. reported that the size of micelles significantly influenced their blood circulation time, tumor accumulation, and tumor penetration. [5] Additionally, nanoparticles exhibited sizedependent antibacterial activity and biofilm penetration properties. [6] Typically, small NSs possess the advantages of: 1) high surface-to-volume ratio that provides them with a large surface by which to contact the biological environment, [6b] 2) excellent biosafety and biocompatibility owing to their ease of excretion from living systems, [7] 3) capability to cross intracellular or in vivo barriers such as cell nuclear membranes [8] and blood-brain barriers (BBBs) [9] that allows them to enter these difficult-to-reach regions, and 4) strong penetration ability to reach the depths of solid tumors [10] and bacterial biofilms. [11] In comparison, large NSs typically exhibit long tissue retention periods [12] and slow exocytosis rates from the cells, [13] both of which are ideal for long-term imaging and effective treatment. Moreover, certain large NSs possess more favorable properties than do small ones in regard to enhanced theranostics. [14] To achieve satisfactory theranostic performance in addition to acceptable biosafety, NSs should exhibit the merits of both small and large NSs, and these merits include long-term retention, deep penetration, and rapid clearance. Among the various strategies used for overcoming the size paradox, utilizing size-transformable NSs has been demonstrated to be an available and effective method, as these types of NSs can easily integrate the advantages of small and large NSs. They can behave as small NSs for tissue penetration, rapid clearance, and crossing biological barriers, and can act as large NSs to meet the demands of long-term retention at the targeted sites. During or after the size transformation in these NSs, the loaded drugs within the NSs can be exposed or released from the system, ultimately enabling the transformable NSs to provide a versatile platform for disease theranostics. Based on their superior properties, a great deal of progress in regard to the design and applications of size-transformable NSs has occurred over the last several decades. [15] In this review, we focus on summarizing the design methods and biomedical applications of two types of size-transformable NSs, specifically the size-decreasing and size-increasing NSs. In addition to the The size of nanostructures (NSs) strongly affects their chemical and physical properties and further impacts their actions in biological systems. Both small and large NSs possess respective advantages for disease theranostics, and this therefore presents a paradox when choosing NSs with suitable sizes. To overcome this challenge, size-transformable NSs have emerged as a powerful tool,...

Adapting and Remolding: Orchestrating Tumor Microenvironment Normalization with Photodynamic Therapy by Size Transformable Nanoframeworks

“…[8][9][10][11] By manipulating the component size, structure hierarchy and surface chemistry,t he nanovehicles featuring size transformation in response to TME cues could circumvent the stroma-shaped penetration barrier, uplifting the effective dose of therapeutic agents in deep-seated tumor. [12][13][14] In this regard, developing versatile platform with controllable nanomaterials that are adaptive to therapeutic barriers in TME exhibits potent efficacy to kill tumor cells directly.H owever,m erely avoiding TME barriers in the transportation of therapeutic components is inadequate for the clearance of solid tumors. [15] Ac rucial factor that cannot be overlooked is the nature of TME, which nourishes residual tumor cells to facilitate their metastasis and causes failure of many tumor cell-specific therapies.…”

Dual Gate‐Controlled Therapeutics for Overcoming Bacterium‐Induced Drug Resistance and Potentiating Cancer Immunotherapy

“…[15] Theaddition of HAase in the solutions had anegligible effect on the drug release from Gem/Cip@SiPNG.A fter HA coating,t he release rates of both Gem and Cip significantly decreased in an eutral environment (Figure 1G and I). Moreover,o wing to the HA degradability of HAase and pH sensitivity of the nanoreservoirs,t he drugs could be fast released from Gem/ Cip@SiPNG@HA in an acidic environment containing HAase.B ecause the tumor microenvironment and cellular endosomes/lysosomes are weakly acidic and have abundant HAases, [16] the loaded drugs could be fast released from Gem/ Cip@SiPNG@HA in tumor regions.…”

Tumor acid microenvironment-activated self-targeting & splitting gold nanoassembly for tumor chemo-radiotherapy

“…Studies have found that the size of nanomedicines should keep at 10–500 nm for better blood circulation, since the nanomedicines (>500 nm and <10 nm) are easily and quickly cleared by the lungs and kidneys, respectively [ 5 ]. While the smaller nanomedicines are more conducive to penetration in the tumor, such as 3–7 nm ultrasmall platinum nanoparticles [ [6] , [7] , [8] , [9] , [10] , [11] , [12] , [13] ]. Moreover, to avoid being recognized and eliminated by the immune system, the surface electrical properties of nanomedicines are best to maintain neutral or negative [ 10 ], and the hydrophobic targeting ligands are not exposed on the surface as much as possible.…”