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Review
. 2021 Oct 26;26(21):6453.
doi: 10.3390/molecules26216453.

Use of Polyhedral Oligomeric Silsesquioxane (POSS) in Drug Delivery, Photodynamic Therapy and Bioimaging

Paula Loman-Cortes  1   2 , Tamanna Binte Huq  1   2 , Juan L Vivero-Escoto  1   2   3
Affiliations
Review

Use of Polyhedral Oligomeric Silsesquioxane (POSS) in Drug Delivery, Photodynamic Therapy and Bioimaging

Paula Loman-Cortes et al. Molecules. .

Abstract

Polyhedral oligomeric silsesquioxanes (POSS) have attracted considerable attention in the design of novel organic-inorganic hybrid materials with high performance capabilities. Features such as their well-defined nanoscale structure, chemical tunability, and biocompatibility make POSS an ideal building block to fabricate hybrid materials for biomedical applications. This review highlights recent advances in the application of POSS-based hybrid materials, with particular emphasis on drug delivery, photodynamic therapy and bioimaging. The design and synthesis of POSS-based materials is described, along with the current methods for controlling their chemical functionalization for biomedical applications. We summarize the advantages of using POSS for several drug delivery applications. We also describe the current progress on using POSS-based materials to improve photodynamic therapies. The use of POSS for delivery of contrast agents or as a passivating agent for nanoprobes is also summarized. We envision that POSS-based hybrid materials have great potential for a variety of biomedical applications including drug delivery, photodynamic therapy and bioimaging.

Keywords: biomedical applications; drug delivery systems (DDS); imaging; photodynamic therapy (PDT); polyhedral oligomeric silsesquioxane (POSS).

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Scheme 1
Scheme 1
Schematic representation of POSS as a cube where the Si atoms are localized in the corner. R groups are substituents to the POSS that can tune its physicochemical properties or be used for further chemical modification.
Scheme 2
Scheme 2
The physicochemical properties of POSS can be engineered through functionalization, polymerization and/or self-assembly.
Scheme 3
Scheme 3
Synthetic strategies for the fabrication of POSS derivatives.
Figure 1
Figure 1
(A) Synthesis procedure of pyridyldisulfanyl-functionalized POSS (POSS−PDS). (B) Fabrication of SP-DTX nanoparticles which self-assembled from amphiphilic star-shaped POSS-based conjugates. Reprinted with permission from ref. [92]. Copyright 2016 American Chemical Society.
Figure 2
Figure 2
In vivo anticancer efficacy of various DTX formulations. (A) Tumor growth curves after intravenous injection of either saline, DTX, DTXLEV, P-DTX, SP-DTX-C, SP-DTX-A, or SP-DTX on mice bearing stroma-rich prostate xenograft tumors every 5 days for four times (5 mg/kg DTX). At the end of experiment, (B) isolated tumors were weighed and (C) photographed. (D) Body weight changes and (E) survival rates were monitored. (F) Effects of different treatments on the inhibition of CAF growth by α-SMA staining (red), the induction of apoptosis by TUNEL staining (green), and the histological examination by H&E staining of tumor tissues. Blue signal derived from nuclei stained by DAPI (n = 5, * p < 0.05, # p < 0.01 vs. SP-DTX). Reprinted with permission from ref. [92]. Copyright 2016 American Chemical Society.
Figure 3
Figure 3
Synthetic processes of bioreducible POSS-based gene vectors via ATRP where * represents the POSS cage. Reprinted with permission from ref. [26]. Copyright 2014 American Chemical Society.
Figure 4
Figure 4
p 18-4/Ce6-conjugated POSS (PPC) nanoparticles. In vivo PDT efficacy of PPC nanoparticles (n = 4). (a) Tumor images and (b) quantitative analysis of tumor growth after PDT with free Ce6 or PPC nanoparticles in tumor-bearing mice. Differences between groups were tested using one-way ANOVA. * p ≤ 0.05. Histological TUNEL staining for tumor slices harvested from tumor-bearing mice after 22 days of PDT with free Ce6 or PPC nanoparticles. Reprinted with permission from ref. [55]. Copyright 2020 Elsevier.
Figure 5
Figure 5
(a) The formation of PPR NPs and PPR/HCPT NPs and (b) the pH-responsive and light-triggerable nuclear delivery strategy using PPR/HCPT NPs as an example. Reprinted with permission from ref. [98]. Copyright 2018 American Chemical Society.
Figure 6
Figure 6
POSSP derivatives which were synthesized in [27]. POSSPs 1–3 contain hydrophobic groups. POSSPs 4 and 5 are functionalized with hydrophilic moieties.
Figure 7
Figure 7
(a) Schematic representation of the design and work principle of POSS-porphyrin system. (b) Percentage of E. coli viability after treatment with a series of concentrations of PPO under irradiation (12 mW·cm–2, 10 min). (c) Representative photographs of lysogeny broth (LB) agar plates for E. coli treated with a series of concentrations of PPO under white light irradiation. Reprinted with permission from ref. [96]. Copyright 2018 American Chemical Society.
Figure 8
Figure 8
Schematic illustration of the fabrication process and photodynamic therapy of PPP5000 and THPP. (a) Changes of relative tumor volume (V/V0) after mice were treated with saline, THPP, and PPP5000. Differences between groups were tested using one-way ANOVA. ** p ≤ 0.01. (b) Representative photos of mice after treatment. Reprinted with permission from ref. [49]. Copyright 2018 American Chemical Society.
Figure 9
Figure 9
(a) Chemical structure and (b) HR-TEM image of COE-POSS. (c) OPEF and (d) OPEF/transmission overlapped images of MCF-cells stained with 1 μM COE-POSS. The signals are collected above 560 nm upon excitation at 488 nm. TPEF images of MCF-7 cells incubated with 1 μM COE-POSS (e) or SG (f) for 2 h. Reprinted with permission from ref. [62]. Copyright 2010 John Wiley and Sons.
Figure 10
Figure 10
(a) Illustration for the hydrolytic condensation of APTES to produce OA-POSS and (b) preparation of carbon dots (CDs/POSS) with glycerol as carbon source and OA-POSS as passivation agent. Fluorescent microscope images of (A2–C2) MCF-7 cells labeled with CDs/POSS. (A2) Bright-field images; (B2) with an excitation wavelength of 340 nm; (C2) with an excitation wavelength at 495 nm. Reprinted with permission from ref. [42]. Copyright 2015 American Chemical Society.
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