Platform For Release Research Articles

Protein Release by Controlled Desorption from Transiently Cationic Nanoparticles.

Therapeutic release from hydrogels is traditionally controlled by encapsulation within nanoparticles; however, this strategy is limited for the release of proteins due to poor efficiency and denaturation. To overcome this problem, we designed an encapsulation-free release platform where negatively charged proteins are adsorbed to the exterior of transiently cationic nanoparticles, thus allowing the nanoparticles to be formulated separately from the proteins. Release is then governed by the change in nanoparticle surface charge from positive to neutral. To achieve this, we synthesized eight zwitterionic poly(lactide-block-carboxybetaine) copolymer derivatives and formulated them into nanoparticles with differing surface chemistry. The nanoparticles were colloidally stable and lost positive charge at rates dependent on the hydrolytic stability of their surface ester groups. The nanoparticles (NPs) were dispersed in a physically cross-linked hyaluronan-based hydrogel with one of three negatively charged proteins (transferrin, panitumumab, or granulocyte-macrophage colony-stimulating factor) to assess their ability to control release. For all three proteins, dispersing NPs within the gels resulted in significant attenuation of release, with the extent modulated by the hydrolytic stability of the surface groups. Release was rapid from fast-hydrolyzing ester groups, reduced with slow-hydrolyzing bulky ester groups, and very slow with nonhydrolyzing amide groups. When positively charged lysozyme was loaded into the nanocomposite gel, there was no significant attenuation of release compared to gel alone. These data demonstrate that electrostatic interactions between the protein and NP are the primary driver of protein release from the hydrogel. All released proteins retained bioactivity as determined with in vitro cell assays. This release strategy shows tremendous versatility and provides a promising new platform for controlled release of anionic protein therapeutics.

Novel carboxymethyl cellulose-halloysite-polyethylene glycol nanocomposite for improved 5-FU delivery

Drug nano-carriers are crucial for achieving targeted treatment against cancer disorders with minimal side effects. In this study, a pH-responsive nanocomposite based on halloysite nanotube (HNT) coated with carboxymethyl cellulose (CMC)/polyethylene glycol (PEG) hydrogel for controlled delivery of 5-Fluorouracil (5-FU), a hydrophobic chemotherapy drug prescribed for different types of cancers was synthesized for the first time using the water-in-oil-in-water (W/O/W) technique. The developed CMC/PEG/HNT/5-FU nanocomposite was characterized by dynamic light scattering (DLS), zeta potential, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Field emission scanning electron microscope (FE-SEM) to get information about the particle size, surface charge, interactions between functional groups, crystalline structure and morphology, respectively. High efficiencies in terms of drug entrapment and loading (46 % and 87 %, respectively) were attained. In-vitro drug release results revealed an improved and sustained 5-FU delivery in an acid environment compared to the physiological medium, corroborating the pH-sensitivity of the developed nano-carrier. Flow cytometry and MTT assays demonstrated that the 5-FU loaded nanocomposite had considerable cytotoxicity on MCF-7 breast cancer cells while it is not toxic against L929 fibroblast cells. The nanocomposite synthesized herein could serve as a platform for the pH-sensitive release of anti-cancer drugs.

High strength, controlled release of curcumin-loaded ZIF-8/chitosan/zein film with excellence gas barrier and antibacterial activity for litchi preservation

Polysaccharide films containing protein additives have good application prospects in agriculture and food field. However, interfacial incompatibility between hydrophobic proteins and hydrophilic polymers remains a major technical challenge. In this work, the interfacial compatibility between hydrophobic zein and hydrophilic chitosan (CS) is improved by the chemical crosslinking between zinc ions of curcumin-loaded zeolitic imidazolate framework-8 (Cur-ZIF-8) with CS and zein. With the improvement of interface compatibility, the results show that the elongation at break and O2 barrier property of synthesized Cur-ZIF-8/CS/Zein are 9.2 and 1.5 times higher than CS/Zein, respectively. And the Cur-ZIF-8/CS/Zein exhibits superior antibacterial and antioxidant properties as well. Importantly, Cur-ZIF-8/CS/Zein can also be used as an intelligent-responsive release platform for curcumin. As a result, Cur-ZIF-8/CS/Zein can keep the freshness and appearance of litchi at least 8 days longer than that of CS/Zein. Therefore, this study provides a novel method to improve the interfacial compatibility between hydrophobic proteins and hydrophilic polymers, and is expected to expand the application of protein/polymer composites in agriculture and food field.

A photothermal-response oxygen release platform based on a hydrogel for accelerating wound healing

During wound healing, oxygen availability and the anti-inflammatory microenvironment play an important role in the formation of new tissue. However, providing continuous and controllable oxygen around the injured tissue while inhibiting inflammation and realizing the synergistic effect of oxygen supply and anti-inflammation is still a major problem affecting the regeneration and repair of wound tissue. Inspired by skin wound pathology and the inflammatory microenvironment, a photothermal response-assisted strategy was developed in this study. We prepared a composite hydrogel system of polydopamine-hyaluronic acid (PDA-HA) hydrogel-loaded calcium peroxide-indocyanine green combined with lauric acid and manganese dioxide (CaO2-ICG@LA@MnO2) nanoparticles that showed excellent photothermal performance under near-infrared (NIR) irradiation and realized the on-off release of oxygen and reactive oxygen species (ROS). Controllable and sustainable oxygen release can promote the regeneration and repair of damaged tissue, and the generated ROS can effectively inhibit the outbreak of inflammation at the initial stage of wound healing. We believe that the system we have developed can be used in a new approach for treating chronic wounds.

Suspended bubble microcapsule delivery systems from droplet microfluidic technology for the local treatment of gastric cancer

Microcapsules are promising drug carriers for disease treatment. Specifically, for drug delivery in the stomach, a key point is to enable retention of the carriers regardless of gastric emptying and peristalsis. Here, we designed novel drug-loaded bubble microcapsules, which were prepared by microfluidic technology and used for oral drug delivery. The bubble microcapsules were composed of a PLGA shell and a bubble core, which was derived from osmotic-triggered cavitation. The PLGA shell ensured efficient drug encapsulation and sustained release; the bubble core enabled retention of the microcapsules in the stomach and thus facilitated long-term treatment. Based on this, we confirmed anti-tumor effects of drug-loaded bubble microcapsules in vivo and in vitro. The drug-loaded bubble microcapsules significantly inhibited the growth and metastasis of tumors. These results suggest that the suspended bubble microcapsules can be used as an ideal drug release platform for cancer therapy. It is foreseeable that the suspension bubble microcapsules prepared by this method would have broader application prospects as oral delivery vehicles for the treatment of gastrointestinal diseases.

Liposome-tethered supported lipid bilayer platform for capture and release of heterogeneous populations of circulating tumor cells.

Because of scarcity, vulnerability, and heterogeneity in the population of circulating tumor cells (CTCs), the CTC isolation system relying on immunoaffinity interaction exhibits inconsistent efficiencies for all types of cancers and even CTCs with different phenotypes in individuals. Moreover, releasing viable CTCs from an isolation system is of importance for molecular analysis and drug screening in precision medicine, which remains a challenge for current systems. In this work, a new CTC isolation microfluidic platform was developed and contains a coating of the antibody-conjugated liposome-tethered-supported lipid bilayer in a developed chaotic-mixing microfluidic system, referred to as the "LIPO-SLB" platform. The biocompatible, soft, laterally fluidic, and antifouling properties of the LIPO-SLB platform offer high CTC capture efficiency, viability, and selectivity. We successfully demonstrated the capability of the LIPO-SLB platform to recapitulate different cancer cell lines with different antigen expression levels. In addition, the captured CTCs in the LIPO-SLB platform can be detached by air foam to destabilize the physically assembled bilayer structures due to a large water/air interfacial area and strong surface tension. More importantly, the LIPO-SLB platform was constructed and used for the verification of clinical samples from 161 patients with different primary cancer types. The mean values of both single CTCs and CTC clusters correlated well with the cancer stages. Moreover, a considerable number of CTCs were isolated from patients' blood samples in the early/localized stages. The clinical validation demonstrated the enormous potential of the universal LIPO-SLB platform as a tool for prognostic and predictive purposes in precision medicine.

Collection, nucleic acid release, amplification, and visualization platform for rapid field detection of rice false smut.

Rice false smut (RFS) has brought serious food safety problems to the world. Reliable diagnostic tools are needed for the field detection of RFS. Traditional polymerase chain reaction (PCR) is inefficient due to sample transport and preparation, which cannot adapt to the needs of field detection. Herein, we successfully developed a simple, portable microfluidic test platform to rapidly detect RFS. To simplify the operation, we integrated spore purification, nucleic acid release, and amplification into one chip. A micro air pump was used to separate the spores from the impurities and complete the collection of the spores through the airflow. We rapidly lysed spores and released nucleic acids by the benzyl chloride method. The loop-mediated isothermal amplification (LAMP) products could be combined with SYBR Green I to observe the results visually. On-chip sample tests showed that the spore collection efficiency was approximately 78%. By providing on-chip detection results, the chip had 100% specificity and a detection limit of 100 copies/reaction. At the same time, the stability (CV < 5%) and quantitative ability (R2 = 0.989) of the chip were also guaranteed. Through the visual detection of large samples, the on-chip detection results were highly concordant with the classical RT-PCR detection results, and the detection timeliness was greatly enhanced. Compared with RT-PCR, the single-sample detection time was shortened by about twenty minutes. The proposed micro-diagnostic tool did not require any large end-point detection instruments and avoided the complicated operation of nucleic acid extraction. As a result, in the future, our microfluidic chip could be used for rapid and real-time monitoring and early warning of rice false smut spores in rice paddies.

Hydrolyzable emulsions as a dual release platform for hydrophobic drugs and DNA.

Several challenges need to be overcome when applying nucleic acids as therapeutic agents. We developed a new way to control the onset of the release of cholesterol-conjugated oligonucleotides with a simple, versatile, and cheap platform. Moreover, we combine the platform into a dual-release system that can release a hydrophobic drug with zero-order kinetics, followed by a rapid release of cholesterol-conjugated DNA.

Localized Microsphere/Hydrogel for Tumor Immunotherapy of Cardiac Glycoside with Minimal Toxicity.

It has been reported that cardiac glycosides (CGs) commonly used in clinical practice can inhibit tumor growth by inducing immunogenic cell death (ICD), and their positive benefits have been documented in several clinical trials of drug combinations. However, the inherent cardiogenic side effects need to be addressed before CGs can be truly applied in clinical antitumor therapy. In this study, a dual controlled release microsphere/hydrogel platform (OL-M/Gel) was constructed to precisely control the output of oleandrin (OL, one of the representative CGs) in situ in tumors. With the help of this intelligent drug release platform, OL can be released in vitro and in vivo in a sustained and stable manner. The ability of OL to induce ICD and the subsequent antigen presentation and cytotoxic T-cell cascades was first stated, which resulted in potent tumor growth suppression without significant side effects. In addition, the inhibition of autologous tumor recurrence and metastasis by OL-M/Gel was also revealed. This study is expected to break through the inherent bottleneck of CGs and promote their clinical transformation in the field of antitumor treatment.

In vitro and in vivo evaluation of a pH-, microbiota- and time-based oral delivery platform for colonic release

Several formulation strategies have been proposed for oral colon delivery, particularly for the therapy of inflammatory bowel disease (IBD). However, targeting the large intestine remains a challenging goal. The aim of this study was to develop and evaluate a novel type of drug delivery system, which is based on multiple drug release triggers for reliable performance. The system consists of: (i) a drug core, (ii) an inner swellable low-viscosity hydroxypropyl methylcellulose (HPMC) layer, and (iii) an outer film coating based on a Eudragit® S:high-methoxyl (HM) pectin (7:3 w/w) blend, optionally containing chitosan. Convex immediate release tablets (2 or 4 mm in diameter) containing paracetamol or 5-aminosalicylic acid (5-ASA) were coated in a fluid bed. The double-coated tablets exhibited pulsatile release profiles when changing the release medium from 0.1 N HCl to phosphate buffer pH 7.4. Also, drug release was faster in simulated colonic fluid (SCF) in the presence of fecal bacteria from IBD patients compared to control culture medium from tablets with outer Eudragit® S: HM pectin: chitosan coatings. The latter systems showed promising results in the control of the progression of colitis and alteration of the microbiota in a preliminary rat study.

Redox-stimulated co-release of drug and nitric oxide from a dual-functional drug delivery carbohydrate platform

Redox-stimulated drug delivery is an effective method for achieving site-specific drug administration. Drug delivery strategies developed based on natural molecules are highly attractive due to the low biotoxicity and good biosafety. Here, a redox-stimulated platform for drug release was developed by green chemistry to use natural hyaluronic acid (HA) and β-cyclodextrins (β-CDs) bridged by disulfide bonds. The platform was stable in room temperature and allowed for controlled drug release in a simulated oxidation or reduction microenvironment. Interestingly, the platform also possessed glutathione peroxidase (GPx)-like enzymatic activity that can catalyze S-nitrosoglutathione (GSNO) to release nitric oxide (NO). In addition, the carrier material is demonstrated to be a good biosafety, which does not interfere with normal cell growth and cause inflammatory reactions. With the function of catalytic release of NO and extensive redox-stimulated drug release, this polysaccharide-based redox-stimulated drug delivery platform could have attractive potential applications in wound healing, cancer and cardiovascular disease treatment. • A redox-stimulated drug release platform （HCC） based on hyaluronic acid (HA) was successfully prepared. • HCC also had a function of catalytic release of nitric oxide. • HCC was capable of encapsulating therapeutic drugs in two forms - pitavastatin calcium (Pi). • HCC was heat stable, non-endothelial cytotoxicity and didn’t stimulate the production of inflammatory factors.

Incorporating self-healing capability in temperature-sensitive hydrogels by non-covalent chitosan crosslinkers

Through the use of non-covalent chitosan (CS) crosslinkers, reversible yet strong non-covalent interactions are introduced into the poly-N-isopropylacrylamide (PNIPAM) temperature-sensitive hydrogel, which renders desirable mechanical properties, biocompatibility, and most importantly high-level self-healing capability, in combination of facile temperature response near body temperature for drug loading/release. Best overall performance is then reached by optimizing the formulation of CS, N-isopropylacrylamide (NIPAM), acrylic acid (PAA), and acrylamide (AM) in the CS-g-P(NIPAM-AM-AA) graft copolymer system. By virtue of quantum chemical calculations, the nature of a variety of non-covalent interactions within the hydrogel framework is uncovered, those of which between CS and PAM units is found to be superiorly strong, being predominately responsible for the excellent self-healing capability. Synthesis of the hydrogel system simply requires a single-step one-pot procedure, where low cost of all components and the production process is guaranteed. After a series of synthetic optimizations, we notice that hydrogel with NIPAM/AM = 7/1 have the lower critical solution temperature (LCST, 37 °C) corresponding to human body temperature, elongation at break of more than 1500%, strain recovery ratio and stress recovery ratio of 92.89% and 96.15%, remarkable biocompatibility and can provide a good and stable drug loading and release platform. In a nutshell, this study provides a low-cost yet highly viable approach for self-healable thermosensitive hydrogels with biocompatibility, which is appropriate for commercial uses.

Photodynamic Lignin Hydrogels: A Versatile Self-Healing Platform for Sustained Release of Photosensitizer Nanoconjugates

A multifunctional hydrogel that combines the properties of pH-responsiveness as well as controlled release holds enormous potential for antimicrobial photodynamic therapy through the development of wound dressings and coatings. Utilization of lignin (a biodegradable and cost-effective biopolymer) could be advantageous as a sustainable alternative over the conventional hydrogels for photodynamic therapy, which is an underexplored area. In this work, the lignin-based hydrogel was developed, which was found to have remarkable self-healing properties. Moreover, the lignin-based photodynamic hydrogels designed via in situ and ex situ methods were found to be transparent enough (through the variation of lignin concentration) to be utilized for photodynamic therapy applications. The in situ method is an example of lignin hydrogel synthesis which is advantageous as it saves multiple reaction steps of nanoparticle synthesis and incorporation into the hydrogel. However, for the demonstration of photodynamic effect, the lignin-based hydrogels were doped with a photosensitizer (Rose Bengal, RB) and also with RB-conjugated lignin-derived silver nanocomplexes (RB@L-AgNCs). The developed lignin-based nanocomposite hydrogels were characterized through various methods including UV–vis spectroscopy, HRTEM, BET, XRD, FESEM, rheology, and FTIR to determine their material properties. Interestingly, the lignin hydrogels were found to possess pH-responsive properties for controlled release of the incorporated nanoagents. Antimicrobial photodynamic therapy studies were performed using lignin-based nanocomposite hydrogels as well as bare lignin hydrogels through utilization of a green laser for a short time (3 min). Mechanistically, it was observed that the nanocomposite-doped hydrogel worked much better as compared to the native lignin hydrogel due to higher reactive oxygen species (ROS) generation. Furthermore, the antimicrobial photodynamic activity of the developed lignin-based nanocomposite hydrogels was validated through fluorescence microscopy studies (live–dead cell imaging). These developed biodegradable lignin-based nanocomposite hydrogels can be efficiently used for the development of wound dressings and nanocoatings over various surfaces for stimuli responsive antimicrobial effect.

Microencapsulation of the Enzyme Breaker by Double-Layer Embedding Method

SummaryAn effective fracturing fluid should have sufficient viscosity to fracture the oil-bearing layer at the initial stage and should be removed smoothly at a later stage by controlling the release rate of the enzyme. Therefore, the gel-breaking speed of an enzyme breaker in the fracturing fluid is an important factor in enhancing the production of tight formations. Microencapsulation is an efficient technology to improve the embedding rate and stability of the core material. In this study, double-layer microcapsules were successfully prepared by spray drying; porous starch (PS) was used as the core material carrier to adsorb the enzyme; and gum arabic was used as the wall material. The morphology of the microcapsules was detected via fluorescence microscopy and scanning electron microscopy. Furthermore, application testing of the double-layer microcapsules showed that the prepared microcapsules can protect the activity of the enzyme breaker, provide a certain sustained-release performance, and increase the gel-breaking time to 40 minutes. The double-layer microcapsule breaker can be further applied to field activities involving fracturing technology. Therefore, this method can be used to develop a platform for the slow release of various enzymes in industries.

A reconstituted depolarization-induced Ca2+ release platform for validation of skeletal muscle disease mutations and drug discovery.

In skeletal muscle excitation-contraction (E-C) coupling, depolarization of the plasma membrane triggers Ca2+ release from the sarcoplasmic reticulum (SR), referred to as depolarization-induced Ca2+ release (DICR). DICR occurs through the type 1 ryanodine receptor (RyR1), which physically interacts with the dihydropyridine receptor Cav1.1 subunit in specific machinery formed with additional essential components including β1a, Stac3 adaptor protein, and junctophilins. Exome sequencing has accelerated the discovery of many novel mutations in genes encoding DICR machinery in various skeletal muscle diseases. However, functional validation is time-consuming because it must be performed in a skeletal muscle environment. In this study, we established a platform of the reconstituted DICR in HEK293 cells. The essential components were effectively transduced into HEK293 cells expressing RyR1 using baculovirus vectors, and Ca2+ release was quantitatively measured with R-CEPIA1er, a fluorescent ER Ca2+ indicator, without contaminant of extracellular Ca2+ influx. In these cells, [K+]-dependent Ca2+ release was triggered by chemical depolarization with the aid of inward rectifying potassium channel, indicating a successful reconstitution of DICR. Using the platform, we evaluated several Cav1.1 mutations that are implicated in malignant hyperthermia and myopathy. We also tested several RyR1 inhibitors; whereas dantrolene and Cpd1 inhibited DICR, procaine had no effect. Furthermore, twitch potentiators such as perchlorate and thiocyanate shifted the voltage dependence of DICR to more negative potentials without affecting Ca2+-induced Ca2+ release. These results well reproduced the findings with the muscle fibers and the cultured myotubes. Since the procedure is simple and reproducible, the reconstituted DICR platform will be highly useful for the validation of mutations and drug discovery for skeletal muscle diseases.

Electrochemical Recovery and Concentration of Noble Metals

Noble metals are integral materials to chemical and electronics industries for their unmatched chemical inertness, electrical conductivity, and catalytic activity. However, the growing demand for noble metals such as Pt, Pd, and Au is outpacing the dwindling supply, and without new recycle strategies these critical noble metal resources will run out. Therefore, energy and resource efficient noble metal recycling technologies are critical to develop sustainable use of these scarce and valuable resources. Recently, electrification of chemical process units has been receiving justifiable attention as an easily scalable means of increasing energy and material sustainability in industry, particularly for chemical separations. In particular, the incorporation of redox-active materials has been met with great success for chemical energy storage and chemical separations due to enhanced charge transfer and easily tunable target ion interactions. Here, we introduce an electrochemically mediated platform for capture, release, and up-concentration of noble metal complexes from mining ore, electronic waste, and valuable elements in industrial manufacturing, where favorable charge transfer binding of noble metals to electrode bound redox sites enables selective capture of target noble metals over other common competitors – all with the flick of a switch. Highlights of our system are its high uptake (>200 mg/g), selectivity (>5 vs competing ions), energy efficiency (<5 kJ/g-PGM), cyclability (>5000 reuse cycles), and scalability to flow system. Technoeconomic analysis of our system compared to current industrial separation technologies indicates economically significant improvements in capital and operating costs with our electrochemical noble metal recycling platform. By lowering the economic barrier of noble metal recycling, these critical materials can be sustainably used and reused for years to come.

Development of Surface Chemical Strategies for Synthesizing Redox-Responsive Diatomite Nanoparticles as a Green Platform for On-Demand Intracellular Release of an Antisense Peptide Nucleic Acid Anticancer Agent.

Redox-responsive silica drug delivery systems are synthesized by aeco-friendly diatomite source to achieve on-demand release of peptide nucleic acid (PNA) in tumor reducing microenvironment, aiming to inhibit the immune checkpoint programmed cell death 1 receptor/programmed cell death receptor ligand 1 (PD-1/PD-L1) in cancer cells. The nanoparticles (NPs) are coated with polyethylene glycol chains as gatekeepers to improve their physicochemical properties and control drug release through the cleavable disulfide bonds (S-S) in a reductive environment. This study describes different chemical conditions to achieve the highest NPs' surface functionalization yield, exploring both multistep and one-pot chemical functionalization strategies. The best formulation is used for covalent PNA conjugation via the S-S bond reaching a loading degree of 306 ± 25µg PNA mg-1 DNPs . These systems are used for in vitro studies to evaluate the kinetic release, biocompatibility, cellular uptake, and activity on different cancer cells expressing high levels of PD-L1. The obtained results prove the safety of the NPs up to 200µg mL-1 and their advantage for controlling and enhancing the PNA intracellular release as well as antitumor activity. Moreover, the downregulation of PD-L1 observed only with MDA-MB-231 cancer cells paves the way for targeted immunotherapy.

De novo synthesis of a MIL-125(Ti) carrier for thermal- and pH-responsive drug release.

Microporous round cake-like (diameter: 900±100nm) MIL-125(Ti) carrier with a central metal (Ti) exhibiting bio-affinity and possessing a great potential to be used as drug release platform, has been synthesized in the present study. The thermal and pH responsiveness of drug delivery systems (DDS) are the most important parameters for drug release and can be provided through polymer coating techniques. The Pluronic F127 (F127) and chitosan (CH) monomers were inserted into the crystal lattice of MIL-125(Ti) carrier during the de novo synthesis process, which were subsequently loaded with doxorubicin (DOX). The results reveal particle size changes (ranged between 30 and 50%) from the original size of the MIL-125(Ti) carrier in response to temperature and pH when the carrier reaches acid environment. The drug release profiles have been completed through self-design device, which provides for the real-time release in the DOX amounts via UV-Vis spectra. The kinetics analysis was used to evaluate the R2 values of first order, Higuchi, Korsmeyer-peppas, and Weibull fitting equations, where the Weibull fitting indicated the best R2. An increase by 59.3% of DOX released under the acid status (pH=5.4) was observed, indicating that the CH-MIL-125(Ti) carrier is temperature and pH responsive. Moreover, the lattice explosion resulting from the temperature increase in the range of 25-42°C caused an increase in F127-MIL-125(Ti) by 30.8-38.3%. The simulated SAXS/WAXS studies for the microstructures of MIL-125(Ti) based DDS at different temperatures after polymer coating (F127-MIL-125(Ti)) provide the possible mechanism of lattice explosion. As such, the responsive Ti-MOF has a highly potential for use in the applications of cancer treatment.

RuNO-Thnl-loaded nanoplatform excited by 808 nm near-infrared light for gas release

Förster energy resonance transfer (FRET) refers to a type of non-radiative energy transfer between two chromophores. In addition to the distance between the donor and acceptor, it depends on the extent of overlap between the fluorescence spectrum of the donor and the absorption spectrum of the acceptor. Based on the principle of FRET, in this study, NIR-responsive nanoplatforms comprising up-conversion nanoparticles (UCNPs)@mSiO2&RuNO-Thnl were designed for the targeted and controllable release of NO. First, core–shell UCNPs were prepared by the thermal decomposition method and then coated with a mesoporous silica layer by surface modification. The prepared UCNPs@mSiO2 was excited by NIR at 808 nm, which avoided the overheating of Yb3+ and increased the penetration depth; in addition, it imparted drug-loading capability and biocompatibility to the UCNPs. Subsequently, RuNO-Thnl and UCNP@mSiO2 were combined using van der Waals forces. Furthermore, UCNPs@mSiO2 converted 808 nm NIR laser irradiation into ultraviolet light or visible light, thereby exciting RuNO-Thnl for the effective local release of NO. The results showed that this NO release platform can release 0.0012–0.0037 μmol/mL of NO gas when the concentration of the solution containing the nanoplatform is in the range of 0.15–0.8 mg/mL, allowing for concentration-controlled NO release on demand. Importantly, the temperature changes generated during the conversion process were not harmful to cells and tissues. This targeted and controlled release approach has broad application prospects in NO-based medical therapy.

Green and multifunctional chitosan-based conformal coating as a controlled release platform for fruit preservation

Food waste caused by the decay of perishable foods is a serious global issue. However, traditional preservative materials don't perform well in preventing food decay. Here, a green and multifunctional conformal coating is prepared by the hydrogen-bonding interactions among chitosan, nano-humic acid and curcumin, which is different from traditional preservative films obtained by solution blending. Thanks to the formation of hydrogen-bonding network, the surface roughness of the coating increased from 9.43 nm to 33.3 nm, which makes it more matches with the micro/nano structure of the fruit surface and obtains a good coating effect for various fruits. Furthermore, this coating shows distinctive mechanical properties (the tensile strength of 31.4 MPa), antioxidant and antibacterial activities (the inhibition zone ≥5 mm), and can be used to control the long-term release (up to 38 days) of natural preservative onto fruit surfaces. Through the demonstration of four perishable fruits, the coating can keep freshness and appearance at least 9 days longer than the uncoated samples, confirming the universal effectiveness of the coating in preventing fruit decay. This coating is easy to produce and use, washable, degradable, and makes from cheap or waste renewable biomaterials, which does not cause additional health and environmental concerns.