Therapeutic nanoparticles (TNPs) aim to deliver drugs more safely and effectively to cancers, yet clinical results have been unpredictable owing to limited in vivo understanding. Here we use single-cell imaging of intratumoral TNP pharmacokinetics and pharmacodynamics to better comprehend their heterogeneous behaviour. Model TNPs comprising a fluorescent platinum(IV) pro-drug and a clinically tested polymer platform (PLGA-b-PEG) promote long drug circulation and alter accumulation by directing cellular uptake toward tumour-associated macrophages (TAMs). Simultaneous imaging of TNP vehicle, its drug payload and single-cell DNA damage response reveals that TAMs serve as a local drug depot that accumulates significant vehicle from which DNA-damaging Pt payload gradually releases to neighbouring tumour cells. Correspondingly, TAM depletion reduces intratumoral TNP accumulation and efficacy. Thus, nanotherapeutics co-opt TAMs for drug delivery, which has implications for TNP design and for selecting patients into trials.

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Tumour-associated macrophages act as a slow-release reservoir of nano-therapeutic Pt(IV) pro-drug

Reversal of multidrug resistance by stimuli-responsive drug delivery systems for therapy of tumor.

Covalently antibacterial alginate-chitosan hydrogel dressing integrated gelatin microspheres containing tetracycline hydrochloride for wound healing.

Stimuli-responsive nanoparticles have the potential to improve the delivery of therapeutics to a specific cell or region within the body. There are many stimuli that have shown potential for specific release of cargo, including variation of pH, redox potential, or the presence of enzymes. pH variation has generated significant interest for the synthesis of stimuli-responsive nanoparticles because nanoparticles are internalized into cells via vesicles that are acidified. Additionally, the tumor microenvironment is known to have a lower pH than the surrounding tissue. In this review, different strategies to design pH-responsive nanoparticles are discussed, focusing on the use of charge-shifting polymers, acid labile linkages, and crosslinking.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/marc.201800917

pH-Responsive Polymer Nanoparticles for Drug Delivery

Preparation and characterization of PVA/nanocellulose/Ag nanocomposite films for antimicrobial food packaging

The potential of self-assembled, pH-responsive nanoparticles of mPEGylated peptide dendron-doxorubicin conjugates for cancer therapy.

Thermal processing of poly(vinyl alcohol) (PVA) has been a big challenge worldwide because its melting point is very close to its decomposition temperature. Based on intermolecular complexation and plasticisation, an amido containing compound (Ac), which has a complementary structure to PVA, together with water, were adopted to improve thermal processing of PVA. The results show that water and Ac can control the supramolecular structure of PVA, confine its crystallisation, decrease its melting point, thus obtain the thermal processing window for PVA. In this way, melt spinning of PVA fibres, extrusion blowing of PVA films and extrusion blowing moulding of PVA containers are realised. Then PVA high performance fibres with tensile strength over 1·9 GPa, PVA blown films with good mechanical properties and transparency, and PVA containers with good gasoline barrier properties and thermal resistance are obtained. Compared with the traditional wet processing of PVA solution, the thermal processing techn...

New technology for thermal processing of poly(vinyl alcohol)

Several modified poly(vinyl alcohol) (PVA) systems with various plasticizers were prepared and their melt-processing was successfully realized. This paper focuses on the study of the evaporation behaviour of water in these modified PVA systems, exploring its plasticizing mechanism by using differential scanning calorimetry. The evaporation characteristics of bulk water, water in aqueous solutions of the plasticizers, and the thermal properties of PVA were also studied. The experimental results show that water in aqueous solutions of glycerol and/or caprolactam evaporates at a lower temperature than bulk water, but water in the PVA/water system evaporates at a higher temperature, with a wider DSC peak due to the interaction between water and PVA. Incorporation of glycerol, caprolactam or their mixtures further strengthens the interactions between water and the other components, retarding water evaporation. During the processing, the less closely associated water has the plasticizing effect through molecule movement, while the strongly bound water, which breaks the intermolecular hydrogen bonding of PVA and decreases its intermolecular interaction, is more beneficial to the melt-processing of PVA. Copyright © 2003 Society of Chemical Industry

Evaporation behaviour of water and its plasticizing effect in modified poly(vinyl alcohol) systems

Thermal blowing of poly(vinyl alcohol) (PVA) film was successfully realized based on molecular complexation. Ways to enhance the performance of the PVA blown films (drawing and surface crosslinking) were studied. The experimental results showed that water exists in PVA films in different states through hydrogen bonds with PVA and other modifiers and influences the drawability of PVA films, as well as the structure and properties of the stretched films. When the initial water content of the film was higher than 35.0%, the draw ratio of the PVA film was quite large because of the effects of the bound water with PVA, as well as the plasticization of free water. With the increase of the initial water content in PVA, the free water content and draw ratio of the films increased but the strength of the films decreased because of the higher residual water in the films. Surface crosslinking can improve the stretchability of PVA films because more water remains in the films and disrupts the hydrogen bonding of PVA. In addition, crosslinking enhances the mechanical properties of stretched PVA films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 774–779, 2005

Enhancing mechanical properties of poly(vinyl alcohol) blown films by drawing and surface crosslinking

The combination of polymer and ionic liquid (IL) is attracting increasing attention because of its versatile and tunable properties. In this paper, the IL 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HOEtMIM]Cl), which has a complementary structure with poly(vinyl alcohol) (PVA), was adopted to act as a novel plasticizer for PVA to improve its thermal processability. The results demonstrated that the hydroxyl group and Cl– in the IL formed strong hydrogen bonds with the hydroxyl groups of PVA, thus efficiently confining its crystallization, decreasing its melting point, and obtaining a wide thermal processing window, up to 110 °C. The resultant PVA/IL composites showed high ionic conductivity, up to 2.82 × 10–3 S/cm, and considerable flexible mechanical properties with an elongation at break of 317% when the IL content was 35 wt %, opening the potential applications of PVA in the field of flexible semisolid state electric double-layer supercapacitors (EDLC) and proton exchange membranes (PEM).

Li Li

Papers

The potential of self-assembled, pH-responsive nanoparticles of mPEGylated peptide dendron-doxorubicin conjugates for cancer therapy.

New technology for thermal processing of poly(vinyl alcohol)

Evaporation behaviour of water and its plasticizing effect in modified poly(vinyl alcohol) systems

Enhancing mechanical properties of poly(vinyl alcohol) blown films by drawing and surface crosslinking

Ionic Liquid Modified Poly(vinyl alcohol) with Improved Thermal Processability and Excellent Electrical Conductivity