Hyper-Crosslinkers Lead to Temperature- and pH-Responsive Polymeric Nanogels with Unusual Volume Change

Facile Reactive Oxygen Species-Scavenging Supramolecular Hydrogel to Promote Diabetic Wound Healing

Chronic wound healing impairment is a significant complication in diabetes. Hydrogels that maintain wound moisture and enable sustained drug release have become prominent for enhancing chronic wound care. Particularly, hydrogels that respond to reactive oxygen species (ROS) are sought-after for their dual capacity to mitigate ROS and facilitate controlled drug delivery at the wound site. We have strategically designed an ROS-responsive and scavenging supramolecular hydrogel composed of the simple hexapeptide Glu-Phe-Met-Phe-Met-Glu (EFM). This hydrogelator, composed solely of canonical amino acids without additional ROS-sensitive motifs, forms a hydrogel rapidly upon sonication. Interaction with ROS leads to the oxidation of Met residues to methionine sulfoxide, triggering hydrogel disassembly and consequent payload release. Cellular assays have verified their biocompatibility and efficacy in promoting cell proliferation and migration. In vivo investigations underscore the potential of this straightforward hydrogel as an ROS-scavenger and drug delivery vehicle, enhancing wound healing in diabetic mice. The simplicity and effectiveness of this hydrogel suggest its broader biomedical applications in the future.

Dual Benefits of Hydrogel Remediation of Cadmium-Contaminated Water or Soil and Promotion of Vegetable Growth under Cadmium Stress

This study aims to solve the problem of cadmium heavy metal ion pollution caused by the abuse of chemical fertilizers and activities such as mining, which pose a serious threat to the plant growth environment. We successfully synthesized DMAPAA (N-(3-(Dimethyl amino) propyl) acrylamide)/DMAPAAQ (N, N-Dimethyl amino propyl acrylamide, methyl chloride quaternary) hydrogels via free radical polymerization. Subsequently, we conducted experiments on this hydrogel for growing vegetables under cadmium stress conditions in aqueous solutions and soil. The cadmium capture capacity of DMAPAA/DMAPAAQ hydrogels under different cadmium ion concentrations and pH values was evaluated by using inductively coupled plasma optical emission spectrometry (ICP). The research results show that under the condition of pH = 7.3, the cadmium capture capacity of DMAPAA/DMAPAAQ hydrogels is the greatest. We used the Langmuir model to fit the adsorption data, and the correlation coefficient was as high as 0.96, indicating that the model fits well. The application of the hydrogels promoted the growth of vegetables in soil under cadmium stress conditions. The results showed that when the added amount of hydrogel was 4%, the dry weight of the vegetables was the largest. In addition, when the added amount of cadmium was 500 mg/kg and the added amount of hydrogel was 4%, the absorption of cadmium by the vegetables decreased to an undetectable level. In summary, the hydrogel successfully synthesized in this study can be effectively used to immobilize cadmium ions in soil while positively promoting the growth and yield of vegetables. This achievement has practical significance for solving the problem of heavy metal ion pollution.

Semiquantitative Solid-State NMR Study of the Adsorption of Soybean Oils on Silica and Its Significance for Rubber Processing

Soybean oil (SBO) is a renewable material used as an alternative to conventional petroleum-derived oils in the processing of rubber composites. Upon chemical modifications, such as epoxidation, its performance in the processing of rubber can be significantly improved, as indicated by a considerable reduction of the mixing energy. Although it has been hypothesized that hydrogen bonding between functional groups (e.g., epoxy) of SBOs and silanols present on the silica surface plays a key role, there is still a lack of direct evidence supporting this hypothesis. In this work, it is demonstrated that there is an overall correlation between the epoxy concentration of SBOs and the mixing energy, consistent with the long-held hypothesis. In particular, a correlation between the SBO-silica adsorption affinity and the degree of epoxidation is revealed by a set of surface-selective solid-state nuclear magnetic resonance (ssNMR) experiments. In addition, the surface-selective ssNMR technique demonstrated in this work could also be used to evaluate the adsorption affinity of other oils and/or additives more broadly.

Novel Multifunctional Stimuli-Responsive Nanoparticles for Synergetic Chemo-Photothermal Therapy of Tumors

In this study, a novel class of multifunctional responsive nanoparticles is designed and fabricated as drug nanocarriers for synergetic chemo-photothermal therapy of tumors. The proposed nanoparticles are composed of a thermo-/pH-responsive poly(N-isopropylacrylamide-co-acrylic acid) (PNA) nanogel core, a polydopamine (PDA) layer for photothermal conversion, and an outer folic acid (FA) layer as a targeting agent for the folate receptors on tumor cells. The fabricated nanoparticles show good biocompatibility and outstanding photothermal conversion efficiency. The proposed nanoparticles loaded with doxorubicin (DOX) drug molecules are stable under physiological conditions with low leakage of drugs, while rapidly release drugs in environments with low pH conditions and at high temperature. The experimental results show that the drug release process is mainly governed by Fickian diffusion. In vitro cell experimental results demonstrate that the PNA-DOX@PDA-FA nanoparticles can be phagocytized by 4T1 tumor cells and release drugs in tumor cell acidic environments, and confirm that the combined chemo and photothermal therapeutic efficacy of PNA-DOX@PDA-FA nanoparticles is higher than the photothermal therapeutic efficacy or the chemotherapeutic efficacy alone. The proposed multifunctional responsive nanoparticles in this study provide a novel class of drug nanocarriers as a promising tool for synergetic chemo-photothermal therapy of tumors.

pH-Sensitive nanogels for drug delivery in cancer therapy

Compared to normal tissue, solid tumors exhibit a lower pH value. Such pH gradient can be used to design pH-sensitive nanogels for selective drug delivery. The acid-sensitive elements in the nanogel cause it to swell/degrade rapidly, followed by rapid drug release.

Size-Transformable Nanostructures: From Design to Biomedical Applications

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, as they can be manipulated to possess the merits of both types of NSs. Herein, various strategies to construct size-transformable NSs are summarized, and the recent research progress regarding their biomedical applications, particularly within the fields of cancer and bacterial theranostics, is highlighted. This review will inspire researchers to further develop various methods that can be used to construct size-transformable NSs for use in novel applications within different fields.

Peptide-Induced Self-Assembly of Therapeutics into a Well-Defined Nanoshell with Tumor-Triggered Shape and Charge Switch

Peptide-tuned self-assembly of macromolecular agents (>500 Da) such as therapeutic peptides offers a strategy to improve the properties and biofunctions of degradable nanomaterials, but the tough requirement of macromolecular therapeutics delivery and a lack of understanding of peptide-based self-assembly design present high barriers for their applications. Herein, we developed a new strategy for nanoengineering macromolecular drugs by an elaborate peptide, termed PSP (VVVVVHHRGDC), capable of directly conjugating with cargo to be a PSP-cargo monomer as building block tending to self-assemble into a well-defined nanoshell with tumor-triggered shape and charge switch. As a proof of concept, conjugation PSP to a D-peptide activator of tumor suppressor p53 termed DPMI (1492.5 Da) generated hollow spheres ~80 nm in diameter named PSP-DPMI that disintegrated only in the acidic microenvironment of tumor tissues, followed by integrin-mediated cellular uptake of PSP-DPMI monomers. Importantly, PSP-based self-assembly successfully endowed the DPMI with long circulation time and high cancer-cell-specific intracellular accumulation. PSP-DPMI nanoshells potently inhibited tumor growth in vitro and in vivo by the p53 restoration, while maintaining a highly favorable in vivo safety profile. Out of conventional encapsulation and conjugation, our study showcases a clinically viable novel method to nanoengineer macromolecular agents such as peptide for anticancer therapy and provides a hazard-free alternative strategy for the theranostics delivery.

Enhanced Cellular Ablation by Attenuating Hypoxia Status and Reprogramming Tumor-Associated Macrophages via NIR Light-Responsive Upconversion Nanocrystals

Near-infrared (NIR) light-mediated photodynamic therapy (PDT), especially based on lanthanide-doped upconversion nanocrystals (UCNs), have been extensively investigated as a promising strategy for effective cellular ablation owing to their unique optical properties to convert NIR light excitation into multiple short-wavelength emissions. Despite the deep tissue penetration of NIR light in living systems, the therapeutic efficiency is greatly restricted by insufficient oxygen supply in hypoxic tumor microenvironment. Moreover, the coexistent tumor-associated macrophages (TAMs) play critical roles in tumor recurrence during the post-PDT period. Herein, we developed a unique photosensitizer-loaded UCNs nanoconjugate (PUN) by integrating manganese dioxide (MnO₂) nanosheets and hyaluronic acid (HA) biopolymer to improve NIR light-mediated PDT efficacy through attenuating hypoxia status and synergistically reprogramming TAMs populations. After the reaction with overproduced H₂O₂ in acidic tumor microenvironment, the MnO₂ nanosheets were degraded for the production of massive oxygen to greatly enhance the oxygen-dependent PDT efficiency upon 808 nm NIR light irradiation. More importantly, the bioinspired polymer HA could effectively reprogram the polarization of pro-tumor M2-type TAMs to anti-tumor M1-type macrophages to prevent tumor relapse after PDT treatment. Such promising results provided the great opportunities to achieve enhanced cellular ablation upon NIR light-mediated PDT treatment by attenuating hypoxic tumor microenvironment, and thus facilitated the rational design of new generations of nanoplatforms toward immunotherapy to inhibit tumor recurrence during post-PDT period.

Functional Hyper-Crosslinkers

Crosslinking is an essential architecture for polymers to improve mechanical and thermal properties and to form three-dimensional (3D) structures. Although conventional synthetic crosslinkers usually only serve as bridges between different polymeric chains, biological crosslinkers are multifunctional. Recently, crosslinkers with active functionality after polymerization are promising a new dimension of molecular design for generating smart materials as they may exhibit dramatic changes in structures and properties in response to external stimuli. This concept article introduces several different designs of hyper-crosslinkers (i.e., multifunctional crosslinkers that provide three or more sites for generating networks) and their applications in tailoring stimuli-responsive and self-healing soft materials. Particularly, the polymeric materials that contain functional hyper-crosslinkers are exhibiting anti-intuitive redox or thermal-pH responses. The goal of this article is to illustrate the concept that functional hyper-crosslinkers not only improve the physical and chemical performance of the polymers, but more importantly, may introduce new architectures and functionalities for soft materials.

A tripeptide-based self-shrinking hydrogel for waste-water treatment: removal of toxic organic dyes and lead (Pb2+) ions

A tripeptide-based supramolecular automatically self-shrinking superhydrogel has been discovered for the efficient removal of toxic organic dyes and Pb²⁺ ions from waste-water.

Revealing the distinct thermal transition behavior between PEGA-based linear polymers and their disulfide cross-linked nanogels

Description of the distinct thermal transition behavior between PEGA-based linear polymers and their disulfide cross-linked nanogels at a molecular level.