Focal Infection Treatment using Laser-Mediated Heating of Injectable Silk Hydrogels with Gold Nanoparticles

Application of Silicone in Ophthalmology: A Review

This paper reviews the latest trends and applications of silicone in ophthalmology, especially related to intraocular lenses (IOLs). Silicone, or siloxane elastomer, as a synthetic polymer, has excellent biocompatibility, high chemical inertness, and hydrophobicity, enabling wide biomedical applications. The physicochemical properties of silicone are reviewed. A review of methods for mechanical and in vivo characterization of IOLs is presented as a prospective research area, since there are only a few available technologies, even though these properties are vital to ensure medical safety and suitability for clinical use, especially if long-term function is considered. IOLs represent permanent implants to replace the natural lens or for correcting vision, with the first commercial foldable lens made of silicone. Biological aspects of posterior capsular opacification have been reviewed, including the effects of the implanted silicone IOL. However, certain issues with silicone IOLs are still challenging and some conditions can prevent its application in all patients. The latest trends in nanotechnology solutions have been reviewed. Surface modifications of silicone IOLs are an efficient approach to further improve biocompatibility or to enable drug-eluting function. Different surface modifications, including coatings, can provide long-term treatments for various medical conditions or medical diagnoses through the incorporation of sensory functions. It is essential that IOL optical characteristics remain unchanged in case of drug incorporation and the application of nanoparticles can enable it. However, clinical trials related to these advanced technologies are still missing, thus preventing their clinical applications at this moment.

Silk-based wearable devices for health monitoring and medical treatment

Previous works have focused on enhancing the tensile properties, mechanical flexibility, biocompatibility, and biodegradability of wearable devices for real-time and continuous health management. Silk proteins, including silk fibroin (SF) and sericin, show great advantages in wearable devices due to their natural biodegradability, excellent biocompatibility, and low fabrication cost. Moreover, these silk proteins possess great potential for functionalization and are being explored as promising candidates for multifunctional wearable devices with sensory capabilities and therapeutic purposes. This review introduces current advancements in silk-based constituents used in the assembly of wearable sensors and adhesives for detecting essential physiological indicators, including metabolites in body fluids, body temperature, electrocardiogram (ECG), electromyogram (EMG), pulse, and respiration. SF and sericin play vital roles in addressing issues related to discomfort reduction, signal fidelity improvement, as well as facilitating medical treatment. These developments signify a transition from hospital-centered healthcare toward individual-centered health monitoring and on-demand therapeutic interventions.

Chaotropic Effect-Induced Sol-Gel Transition and Radical Stabilization for Bacterially Sensitive Near-Infrared Photothermal Therapy

Deep-seated bacterial infections (DBIs) are stubborn and deeply penetrate tissues. Eliminating deep-seated bacteria and promoting tissue regeneration remain great challenges. Here, a novel radical-containing hydrogel (SFT-B Gel) cross-linked by a chaotropic effect was designed for the sensing of DBIs and near-infrared photothermal therapy (NIR-II PTT). A silk fibroin solution stained with 4,4',4″-(1,3,5-triazine-2,4,6-triyl)tris(1-methylpyridin-1-ium) (TPT3+) was employed as the backbone, which could be cross-linked by a closo-dodecaborate cluster (B12H122-) through a chaotropic effect to form the SFT-B Gel. More interestingly, the SFT-B Gel exhibited the ability to sense DBIs, which could generate a TPT2+• radical with obvious color changes in the presence of bacteria. The radical-containing SFT-B Gel (SFT-B★ Gel) possessed strong NIR-II absorption and a remarkable photothermal effect, thus demonstrating excellent NIR-II PTT antibacterial activity for the treatment of DBIs. This work provides a new approach for the construction of intelligent hydrogels with unique properties using a chaotropic effect.

Review of Spider Silk Applications in Biomedical and Tissue Engineering

This review will present the latest research related to the production and application of spider silk and silk-based materials in reconstructive and regenerative medicine and tissue engineering, with a focus on musculoskeletal tissues, and including skin regeneration and tissue repair of bone and cartilage, ligaments, muscle tissue, peripheral nerves, and artificial blood vessels. Natural spider silk synthesis is reviewed, and the further recombinant production of spider silk proteins. Research insights into possible spider silk structures, like fibers (1D), coatings (2D), and 3D constructs, including porous structures, hydrogels, and organ-on-chip designs, have been reviewed considering a design of bioactive materials for smart medical implants and drug delivery systems. Silk is one of the toughest natural materials, with high strain at failure and mechanical strength. Novel biomaterials with silk fibroin can mimic the tissue structure and promote regeneration and new tissue growth. Silk proteins are important in designing tissue-on-chip or organ-on-chip technologies and micro devices for the precise engineering of artificial tissues and organs, disease modeling, and the further selection of adequate medical treatments. Recent research indicates that silk (films, hydrogels, capsules, or liposomes coated with silk proteins) has the potential to provide controlled drug release at the target destination. However, even with clear advantages, there are still challenges that need further research, including clinical trials.

Application of Silk-Fibroin-Based Hydrogels in Tissue Engineering

Silk fibroin (SF) is an excellent protein-based biomaterial produced by the degumming and purification of silk from cocoons of the Bombyx mori through alkali or enzymatic treatments. SF exhibits excellent biological properties, such as mechanical properties, biocompatibility, biodegradability, bioabsorbability, low immunogenicity, and tunability, making it a versatile material widely applied in biological fields, particularly in tissue engineering. In tissue engineering, SF is often fabricated into hydrogel form, with the advantages of added materials. SF hydrogels have mostly been studied for their use in tissue regeneration by enhancing cell activity at the tissue defect site or counteracting tissue-damage-related factors. This review focuses on SF hydrogels, firstly summarizing the fabrication and properties of SF and SF hydrogels and then detailing the regenerative effects of SF hydrogels as scaffolds in cartilage, bone, skin, cornea, teeth, and eardrum in recent years.

Advanced Hydrogels Combined with Silver and Gold Nanoparticles against Antimicrobial Resistance

The development of multidrug-resistant (MDR) microorganisms has increased dramatically in the last decade as a natural consequence of the misuse and overuse of antimicrobials. The World Health Organization (WHO) recognizes that this is one of the top ten global public health threats facing humanity today, demanding urgent multisectoral action. The UK government foresees that bacterial antimicrobial resistance (AMR) could kill 10 million people per year by 2050 worldwide. In this sense, metallic nanoparticles (NPs) have emerged as promising alternatives due to their outstanding antibacterial and antibiofilm properties. The efficient delivery of the NPs is also a matter of concern, and recent studies have demonstrated that hydrogels present an excellent ability to perform this task. The porous hydrogel structure with a high-water retention capability is a convenient host for the incorporation of the metallic nanoparticles, providing an efficient path to deliver the NPs properly reducing bacterial infections caused by MDR pathogenic microorganisms. This article reviews the most recent investigations on the characteristics, applications, advantages, and limitations of hydrogels combined with metallic NPs for treating MDR bacteria. The mechanisms of action and the antibiofilm activity of the NPs incorporated into hydrogels are also described. Finally, this contribution intends to fill some gaps in nanomedicine and serve as a guide for the development of advanced medical products.

Silk fibroin hydrogels for biomedical applications

Silk fibroin hydrogels occupy an essential position in the biomedical field due to their remarkable biological properties, excellent mechanical properties, flexible processing properties, as well as abundant sources and low cost. Herein, we introduce the unique structures and physicochemical characteristics of silk fibroin, including mechanical properties, biocompatibility, and biodegradability. Then, various preparation strategies of silk fibroin hydrogels are summarized, which can be divided into physical cross-linking and chemical cross-linking. Emphatically, the applications of silk fibroin hydrogel biomaterials in various biomedical fields, including tissue engineering, drug delivery, and wearable sensors, are systematically summarized. At last, the challenges and future prospects of silk fibroin hydrogels in biomedical applications are discussed.

Harvesting Light To Produce Heat: Photothermal Nanoparticles for Technological Applications and Biomedical Devices

The photothermal properties of nanoparticles (NPs), that is, their ability to convert absorbed light into heat, have been studied since the end of the last century, mainly on gold NPs. In the new millennium, these studies have developed into a burst of research dedicated to the photothermal ablation of tumors. However, beside this strictly medical theme, research has also flourished in the connected areas of photothermal antibacterial surface coatings, gels and polymers, of photothermal surfaces for cell stimulation, as well as in purely technological areas that do not involve medical biotechnology. These include the direct conversion of solar light into heat, a more efficient sun-powered generation of steam and the use of inkjet-printed patterns of photothermal NPs for anticounterfeit printing based on temperature reading, to cite but a few. After an analysis of the photothermal effect (PTE) and its mechanism, this minireview briefly considers the antitumor-therapy theme and takes an in-depth look at all the other technological and biomedical applications of the PTE, paying particular attention to photothermal materials whose NPs have joined those based on Au.

Transdermal Photothermal Sterilization and Abscess Elimination Research of BSA-CuS Nanoparticles in vivo

The treatment of subcutaneous abscess caused by drug-resistant bacteria is facing great difficulties and receiving more attention. In this work, we employed BSA-CuS nanoparticles as a photothermal reagent to apply photothermal therapy (PTT) to combat drug-resistant bacteria in vitro and subcutaneous abscess in vivo. The BSA-CuS nanoparticles were found to be stable and biocompatible without cytotoxicity toward NIH3T3 and 4T1 cells. In vitro experiments showed that three species of drug-resistant pathogens, including Escherichia coli, Staphylococcus aureus, and Candida albicans, could be effectively sterilized under co-incubation with BSA-CuS nanoparticles and then irradiation with 1064 nm NIR laser via tissue penetration. BSA-CuS nanoparticles together with 1064 nm NIR laser irradiation could also effectively diminish subcutaneous abscesses caused by drug-resistant bacteria on mice under PTT and depth PTT without causing any serious side effects and organic damage in vivo.That is OK, thank you!

L-Arg-Rich Amphiphilic Dendritic Peptide as a Versatile NO Donor for NO/Photodynamic Synergistic Treatment of Bacterial Infections and Promoting Wound Healing

The development of alternative strategies for the efficient treatment of subcutaneous abscesses that do not require the massive use of antibiotics and surgical intervention is urgently needed. Herein, a novel synergistic antibacterial strategy based on photodynamic (PDT) and NO gas therapy is reported, in which, a PDT-driven NO controllable generation system (Ce6@Arg-ADP) is developed with l-Arg-rich amphiphilic dendritic peptide (Arg-ADP) as a carrier. This carrier not only displays superior bacterial association and biofilm penetration performance, but also acts as a versatile NO donor. Following efficient penetration into the interior of the biofilms, Ce6@Arg-ADP can rapidly produce massive NO via utilizing the H₂ O₂ generated during PDT to oxidize Arg-ADP to NO and l-citrulline, without affecting singlet oxygen (¹ O₂ ) production. The combination of ¹ O₂ and the reactive by-products of NO offers notable synergistic antibacterial and biofilm eradication effects. Importantly, following efficient elimination of all bacteria from the abscess site, Arg-ADP can further generate trace quantities of NO to facilitate the angiogenesis and epithelialization of the wound tissues, thereby notably promotes wound healing. Together, this study clearly suggests that Arg-ADP is a versatile NO donor, and the combination of PDT and NO represents a promising strategy for the efficient treatment of subcutaneous abscesses.

Gold, Silver, and Iron Oxide Nanoparticle Incorporation into Silk Hydrogels for Biomedical Applications: Elaboration, Structure, and Properties

Silk fibroin (SF) is a versatile material with biodegradable and biocompatible properties, which make it fit for broad biomedical applications. In this context, the incorporation of nanosized objects into SF allows the development of a variety of bionanocomposites with tailored properties and functions. Herein, we report a thorough investigation on the design, characterization, and biological evaluation of SF hydrogels incorporating gold, silver, or iron oxide nanoparticles. The latter are synthesized in aqueous media using a biocompatible ligand allowing their utilization in various biomedical applications. This ligand seems to play a pivotal role in nanoparticle dispersion within the hydrogel. Results show that the incorporation of nanoparticles does not greatly influence the mechanism of SF gelation and has a minor impact on the mechanical properties of the so-obtained bionanocomposites. By contrast, significant changes are observed in the swelling behavior of these materials, depending on the nanoparticle used. Interestingly, the main characteristics of these bionanocomposites, related to their potential use for biomedical purposes, show the successful input of nanoparticles, including antibacterial properties for gold and silver nanoparticles and magnetic properties for iron oxide ones.

Crosslinking strategies for silk fibroin hydrogels: promising biomedical materials

Due to their strong biomimetic potential, silk fibroin (SF) hydrogels are impressive candidates for tissue engineering, due to their tunable mechanical properties, biocompatibility, low immunotoxicity, controllable biodegradability, and a remarkable capacity for biomaterial modification and the realization of a specific molecular structure. The fundamental chemical and physical structure of SF allows its structure to be altered using various crosslinking strategies. The established crosslinking methods enable the formation of three-dimensional (3D) networks under physiological conditions. There are different chemical and physical crosslinking mechanisms available for the generation of SF hydrogels (SFHs). These methods, either chemical or physical, change the structure of SF and improve its mechanical stability, although each method has its advantages and disadvantages. While chemical crosslinking agents guarantee the mechanical strength of SFH through the generation of covalent bonds, they could cause some toxicity, and their usage is not compatible with a cell-friendly technology. On the other hand, physical crosslinking approaches have been implemented in the absence of chemical solvents by the induction of β-sheet conformation in the SF structure. Unfortunately, it is not easy to control the shape and properties of SFHs when using this method. The current review discusses the different crosslinking mechanisms of SFH in detail, in order to support the development of engineered SFHs for biomedical applications.

Silk Polymers and Nanoparticles: A Powerful Combination for the Design of Versatile Biomaterials

Silk fibroin (SF) is a natural protein largely used in the textile industry but also in biomedicine, catalysis, and other materials applications. SF is biocompatible, biodegradable, and possesses high tensile strength. Moreover, it is a versatile compound that can be formed into different materials at the macro, micro- and nano-scales, such as nanofibers, nanoparticles, hydrogels, microspheres, and other formats. Silk can be further integrated into emerging and promising additive manufacturing techniques like bioprinting, stereolithography or digital light processing 3D printing. As such, the development of methodologies for the functionalization of silk materials provide added value. Inorganic nanoparticles (INPs) have interesting and unexpected properties differing from bulk materials. These properties include better catalysis efficiency (better surface/volume ratio and consequently decreased quantify of catalyst), antibacterial activity, fluorescence properties, and UV-radiation protection or superparamagnetic behavior depending on the metal used. Given the promising results and performance of INPs, their use in many different procedures has been growing. Therefore, combining the useful properties of silk fibroin materials with those from INPs is increasingly relevant in many applications. Two main methodologies have been used in the literature to form silk-based bionanocomposites: in situ synthesis of INPs in silk materials, or the addition of preformed INPs to silk materials. This work presents an overview of current silk nanocomposites developed by these two main methodologies. An evaluation of overall INP characteristics and their distribution within the material is presented for each approach. Finally, an outlook is provided about the potential applications of these resultant nanocomposite materials.

Body-Integrated, Enzyme-Triggered Degradable, Silk-Based Mechanical Sensors for Customized Health/Fitness Monitoring and In Situ Treatment

Mechanical signals such as pressure and strain reflect important psychological and physiological states of the human body. Body-integrated sensors, including skin-mounted and surgically implanted ones, allow personalized health monitoring for the general population as well as patients. However, the development of such measuring devices has been hindered by the strict requirements for human-biocompatible materials and the need for high performance sensors; most existing devices or sensors do not meet all the desired specifications. Here, a set of flexible, stretchable, wearable, implantable, and degradable mechanical sensors is reported with excellent mechanical robustness and compliance, outstanding biocompatibility, remotely-triggered degradation, and excellent sensing performance, using a conductive silk fibroin hydrogel (CSFH). They can detect multiple mechanical signals such as pressure, strain, and bending angles. Moreover, combined with a drug-loaded silk-based microneedle array, sensor-equipped devices are shown to be effective for real-time monitoring and in situ treatment of epilepsy in a rodent model. These sensors offer potential applications in custom health monitoring wearables, and in situ treatment of chronic clinical disorders.

Interplay between Light and Functionalized Silk Fibroin and Applications

Silkworm silk has been considered to be a luxurious textile for more than five thousand years. Native silk fibroin (SF) films have excellent (ca. 90%) optical transparency and exhibit fluorescence under UV light. The silk dyeing process is very important and difficult, and methods such as pigmentary coloration and structural coloration have been tested for coloring silk fabrics. To functionalize silk that exhibits fluorescence, the in vivo and in vitro assembly of functional compounds with SF and the resulting amplification of fluorescence emission are examined. Finally, we discuss the applications of SF materials in basic optical elements, light energy conversion devices, photochemical reactions, sensing, and imaging. This review is expected to provide insight into the interaction between light and silk and to inspire researchers to develop silk materials with a consideration of history, material properties, and future prospects.

Photothermally active nanoparticles as a promising tool for eliminating bacteria and biofilms

Bacterial contamination is a severe issue that affects medical devices, hospital tools and surfaces. When microorganisms adhere to a surface (e.g., medical devices or implants) they can develop into a biofilm, thereby becoming more resistant to conventional biocides and disinfectants. Nanoparticles can be used as an antibacterial agent in medical instruments or as a protective coating in implantable devices. In particular, attention is being drawn to photothermally active nanoparticles that are capable of converting absorbed light into heat. These nanoparticles can efficiently eradicate bacteria and biofilms upon light activation (predominantly near the infrared to near-infrared spectral region) due a rapid and pronounced local temperature increase. By using this approach new, protective, antibacterial surfaces and materials can be developed that can be remotely activated on demand. In this review, we summarize the state-of-the art regarding the application of various photothermally active nanoparticles and their corresponding nanocomposites for the light-triggered eradication of bacteria and biofilms.

The antifungal agent of silver nanoparticles activated by diode laser as light source to reduce C. albicans biofilms: an in vitro study

Candida albicans is a normal flora caused fungal infections and has the ability to form biofilms. The aim of this study was to improve the antifungal effect of silver nanoparticles (AgNPs) and the light source for reducing the biofilm survival of C. albicans. AgNPs were prepared by silver nitrate (AgNO₃) and trisodium citrate (Na₃C₆H₅O₇). To determine the antifungal effect of treatments on C. albicans biofilm, samples were distributed into four groups; L + P+ was treatment with laser irradiation and AgNPs; L + P- was treatment with laser irradiation only; L - P+ was treatment with AgNPs only (control positive); L - P- was no treatment with laser irradiation or AgNPs (control negative). The growth of fungi had been monitored by measuring the optical density at 405 nm with ELISA reader. The particle size of AgNPs was measured by using (particle size analyzer) and the zeta potential of AgNPs was measured by using Malvern zetasizer. The PSA test showed that the particle size of AgNPs was distributed between 7.531-5559.644 nm. The zeta potentials were found lower than - 30 mV with pH of 7, 9 or 11. The reduction percentage was analyzed by ANOVA test. The highest reduction difference was given at a lower level irradiation because irradiation with a density energy of 6.13 ± 0.002 J/cm² resulted in the biofilm reduction of 7.07 ± 0.23% for the sample without AgNPs compared to the sample with AgNPs that increased the biofilm reduction of 64.48 ± 0.07%. The irradiation with a 450-nm light source had a significant fungicidal effect on C. albicans biofilm. The combination of light source and AgNPs provides an increase of biofilm reduction compared to the light source itself.

Antibacterial gold nanoparticle-based photothermal killing of vancomycin-resistant bacteria

Aim: The extensive use of vancomycin has given rise to vancomycin-resistant bacterial strains, such as vancomycin-resistant Enterococci (VRE). We aim to explore potent medical treatments that can inhibit the growth of VRE. Materials & methods: Vancomycin-immobilized gold nanoparticles (Au@Van NPs) with polygonal shapes from one-pot reactions were generated within approximately 7 min. Results & discussion: The as-prepared Au NPs exhibit not only antibacterial capability but also photothermal competence. The temperature of the sample solution containing the as-prepared Au@Van NPs can be raised by approximately 15°C under irradiation by a near-infrared laser (λ = 808 nm) within 5 min. Conclusion: The required amount of vancomycin on the as-prepared Au@Van NPs combined with near-infrared irradiation for inhibiting VRE is approximately 16-fold lower than that of free-form vancomycin.

Recent Progress in Polymer Research to Tackle Infections and Antimicrobial Resistance

Global health is increasingly being threatened by the rapid emergence of drug-resistant microbes. The ability of these microbes to form biofilms has further exacerbated the scenario leading to notorious infections that are almost impossible to treat. For addressing this clinical threat, various antimicrobial polymers, polymer-based antimicrobial hydrogels and polymer-coated antimicrobial surfaces have been developed in the recent past. This review aims to discuss such polymer-based antimicrobial strategies with a focus on their current advancement in the field. Antimicrobial polymers, whose designs are inspired from antimicrobial peptides (AMPs), are described with an emphasis on structure-activity analysis. Additionally, antibiofilm activity and in vivo efficacy are delineated to elucidate the real potential of these antimicrobial polymers as possible therapeutics. Antimicrobial hydrogels, prepared from either inherently antimicrobial polymers or biocide-loaded into polymer-derived hydrogel matrix, are elaborated followed by various strategies to engineer polymer-coated antimicrobial surfaces. In the end, the current challenges are accentuated along with future directions for further expansion of the field toward tackling infections and antimicrobial resistance.

pH-triggered charge-reversible of glycol chitosan conjugated carboxyl graphene for enhancing photothermal ablation of focal infection

Subcutaneous abscesses infected by multidrug-resistant bacteria are becoming an increasing challenge to human health. To address this challenge, a surface-adaptive and biocompatible glycol chitosan conjugated carboxyl graphene (GCS-CG) is developed, which exhibits unique self-adaptive target to the acidic microenvironment of abscess (∼pH 6.3) and no damage to the healthy tissue (pH 7.4) around the abscess. Originally, following conjugated with GCS, the absorbance of CG obviously increases in the near-infrared (NIR) region, enabling GCS-CG to generate an increment amount of heat. GCS-CG shows fast pH-responsive surface charge transition from negative to positive, which presents strong adherence to negatively charged bacteria surface in abscess, while exhibits poor affinity to host cells in healthy tissues. The local temperature of NIR-irradiated GCS-CG is estimated to be higher than their ambient temperature, ensuring targeted heating and eradicating the bacteria to reduce the damage to tissue; hence, wound healing is accelerated. Moreover, the in vitro and in vivo biosafety results demonstrate that GCS-CG presents greatly biocompatible even at a high concentration of 1 mg·mL^-1. Given the above advantages as well as the simple preparation, graphene developed here may provide a new potential application as a useful antibacterial agent in the areas of healthcare.

STATEMENT OF SIGNIFICANCE

A surface-adaptive nanomaterial, glycol chitosan conjugated carboxyl graphene (GCS-CG) is developed, which realizes the acidity-triggered bacteria targeting. GCS-CG can result in direct thermal ablation of bacteria and enhancement of the infected wound healing, but exhibit no damage to healthy tissues. The pH-responsive GCS-CG described here, containing no antibiotics, has great potentials in treating bacterial infection and even multidrug-resistant bacteria.

Degradable NIR-PTT Nanoagents with a Potential Cu@Cu2O@Polymer Structure

Cu@Cu₂O@PSMA polymer nanoparticles (Cu@Cu₂O@polymer NPs) with near-infrared (NIR) absorption were successfully synthesized in a single-step oxidation reaction of Cu@PSMA polymer NPs at 100 °C for 20 min. The shape, structure, and optical properties of the Cu@Cu₂O@polymer NPs were tailorable by controlling the reaction parameters, for example, using the initial Cu@PSMA polymer NP as a template and varying the halide ion content, heating temperature, and reaction time. The Cu@Cu₂O@polymer NPs exhibited robust NIR absorption between 650 and 710 nm and possessed superior oxidation resistance in water and culture media. In vitro assays demonstrated the low cytotoxicity of the Cu@Cu₂O@PSMA polymer NPs to HeLa cells through an improved cell viability, high IC₅₀, low injury incidence from the supernatant of the partly dissociated Cu@Cu₂O@PSMA polymer NPs, and minor generation of reactive oxygen species. More importantly, we demonstrated that the inorganic Cu-based nanocomposite [+0.34 V vs normal hydrogen electrode (NHE)] was degradable in an endogenous H₂O₂ (+1.78 V vs NHE) environment. Cu ions were detected in the urine of mice, which illustrates the possibility of extraction after the degradation of the Cu-based particles. 'After an treatment of the HeLa cells with the Cu@Cu₂O@polymer NPs and a 660 nm light-emitting diode, the photoablation of 50 and 90% cells was observed at NP doses of 20 and 50 ppm, respectively. These results demonstrate that NIR-functional and moderate redox-active Cu@Cu₂O@polymer NPs are potential next-generation photothermal therapy (PTT) nanoagents because of combined features of degradation resistance in the physiological environment, enabling the delivery of efficient PTT, a possibly improved ability to selectively harm cancer cells by releasing Cu ions under high-H₂O₂ and/or low-pH conditions, and ability to be extracted from the body after biodegradation.

Membrane interactions and antimicrobial effects of inorganic nanoparticles

Interactions between nanoparticles and biological membranes are attracting increasing attention in current nanomedicine, and play a key role both for nanotoxicology and for utilizing nanomaterials in diagnostics, drug delivery, functional biomaterials, as well as combinations of these, e.g., in theranostics. In addition, there is considerable current interest in the use of nanomaterials as antimicrobial agents, motivated by increasing resistance development against conventional antibiotics. Here, various nanomaterials offer opportunities for triggered functionalites to combat challenging infections. Although the performance in these diverse applications is governed by a complex interplay between the nanomaterial, the properties of included drugs (if any), and the biological system, nanoparticle-membrane interactions constitute a key initial step and play a key role for the subsequent biological response. In the present overview, the current understanding of inorganic nanomaterials as antimicrobial agents is outlined, with special focus on the interplay between antimicrobial effects and membrane interactions, and how membrane interactions and antimicrobial effects of such materials depend on nanoparticle properties, membrane composition, and external (e.g., light and magnetic) fields.

Antibiotic-loaded MoS2 nanosheets to combat bacterial resistance via biofilm inhibition

The emergence of antibiotic resistance has resulted in increasing difficulty in treating clinical infections associated with biofilm formation, one of the key processes in turn contributing to enhanced antibiotic resistance. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance has opened up. Based on the many and diverse properties of MoS2 nanosheets that have attracted wide attention, in particular their antibacterial potential, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of the CM-TH nanocomposites showed the synergetic effect that the combination of nanomaterials and antibiotics was more efficient than either working alone. In particularly, the minimum inhibitory concentration values generally decreased by a factor of dozens, suggesting that CM-TH may become a possible alternative to traditional antibiotics in disrupting biofilms and overcoming antibiotic resistance in treating medical diseases.

White-Light-Induced Collective Heating of Gold Nanocomposite/Bombyx mori Silk Thin Films with Ultrahigh Broadband Absorbance

This paper describes a systematic investigation of the phenomenon of white-light-induced heating in silk fibroin films embedded with gold nanoparticles (Au NPs). The Au NPs functioned to develop an ultrahigh broadband absorber, allowing white light to be used as a source for photothermal generation. With an increase of the Au content in the composite films, the absorbance was enhanced significantly around the localized surface plasmon resonance (LSPR) wavelength, while non-LSPR wavelengths were also increased dramatically. The greater amount of absorbed light increased the rate of photoheating. The optimized composite film exhibited ultrahigh absorbances of approximately 95% over the spectral range from 350 to 750 nm, with moderate absorbances (>60%) at longer wavelengths (750-1000 nm). As a result, the composite film absorbed almost all of the incident light and, accordingly, converted this optical energy to local heat. Therefore, significant temperature increases (ca. 100 °C) were readily obtained when we irradiated the composite film under a light-emitting diode or halogen lamp. Moreover, such composite films displayed linear light-to-heat responses with respect to the light intensity, as well as great photothermal stability. A broadband absorptive film coated on a simple Al/Si Schottky diode displayed a linear, significant, stable photo-thermo-electronic effect in response to varying the light intensity.

Antibacterial and conductive injectable hydrogels based on quaternized chitosan-graft-polyaniline/oxidized dextran for tissue engineering

Biomaterials with injectability, conductivity and antibacterial effect simultaneously have been rarely reported. Herein, we developed a new series of in situ forming antibacterial conductive degradable hydrogels using quaternized chitosan (QCS) grafted polyaniline with oxidized dextran as crosslinker. The chemical structures, morphologies, electrochemical property, conductivity, swelling ratio, rheological property, in vitro biodegradation and gelation time of hydrogels were characterized. Injectability was verified by in vivo subcutaneous injection on a Sprague Dawley rat. The antibacterial activity of the hydrogels was firstly evaluated employing antibacterial assay using Escherichia coli and Staphylococcus aureus in vitro. The hydrogels containing polyaniline showed enhanced antibacterial activity compared to QCS hydrogel, especially for hydrogels with 3 wt% polyaniline showing 95 kill% and 90kill% for E. coli and S. aureus, respectively. Compared with QCS hydrogel, the hydrogels with 3 wt% polyaniline still showed enhanced antibacterial activity for E. coli in vivo. The adipose-derived mesenchymal stem cells (ADMSCs) were used to evaluate the cytotoxicity of the hydrogels and hydrogels with polyaniline showed better cytocompatibility than QCS hydrogel. The electroactive hydrogels could significantly enhance the proliferation of C2C12 myoblasts compared to QCS hydrogel. This work opens the way to fabricate in situ forming antibacterial and electroactive degradable hydrogels as a new class of bioactive scaffolds for tissue regeneration applications.

Development of therapeutic Au-methylene blue nanoparticles for targeted photodynamic therapy of cervical cancer cells

Photodynamic therapy (PDT) involves the cellular uptake of a photosensitizer (PS) combined with oxygen molecules and light at a specific wavelength to be able to trigger cancer cell death via the apoptosis pathway, which is less harmful and has less inflammatory side effect than necrosis. However, the traditional PDT treatment has two main deficiencies: the dark toxicity of the PS and the poor selectivity of the cellular uptake of PS between the target cells and normal tissues. In this work, methylene blue (MB), a known effective PS, combined with Au nanoparticles (NPs) was prepared using an intermolecular interaction between a polystyrene-alt-maleic acid (PSMA) layer on the Au NPs and MB. The Au@polymer/MB NPs produced a high quantum yield of singlet oxygen molecules, over 50% as much as that of free MB, when they were excited by a dark red light source at 660 nm, but without significant dark toxicity. Furthermore, transferrin (Tf) was conjugated on the Au@polymer/MB NPs via an EDC/NHS reaction to enhance the selectivity to HeLa cells compared to 3T3 fibroblasts. With a hand-held single laser treatment (32 mW/cm) for 4 min, the new Au@polymer/MB-Tf NPs showed a 2-fold enhancement of PDT efficiency toward HeLa cells over the use of free MB at 4 times dosage. Cellular staining examinations showed that the HeLa cells reacted with Au@polymer/MB-Tf NPs and the 660 nm light excitation triggered PDT, which caused the cells to undergo apoptosis ("programmed" cell death). We propose that applying this therapeutic Au@polymer/MB-Tf nanoagent is facile and safe for delivery and cancer cell targeting to simultaneously minimize side effects and accomplish a significant enhancement in photodynamic therapeutic efficiency toward next-generation nanomedicine development.

Injectable microbeads with a thermo-responsive shell and a pH-responsive core as a dual-switch-controlled release system

Treating inflammation with a dual-switch-controlled release system: The release of a drug from the developed microbead system occurs only in response to both an increase in local temperature and an acidic environmental pH. This dual-switch-controlled release system has the advantages of distinguishing between inflamed and healthy tissues to improve treatment efficacy.

Surface-modified silk hydrogel containing hydroxyapatite nanoparticle with hyaluronic acid-dopamine conjugate

Silk fibroin/hydroxyapatite (SF/HAp) composite hydrogels were fabricated in this study, having different HAp contents (0-33 wt%) in SF matrix hydrogel. Surface modification of HAp nanoparticle with hyaluronic acid (HA)-dopamine (DA) conjugate improved a dispersibility of HAp in aqueous SF solution due to its negatively charged surface and therefore, fabrication of the SF composite hydrogel having HAp nanoparticles inside could be possible. Zeta potential of surface-modified HAP was examined by ELS. It demonstrates that surface of HAp was well modified to a negative charge with HA-DA. Morphological structure of SF hydrogel containing surface-modified HAp was examined by FE-SEM for analyzing pore structure of hydrogel and deposition of HAp nanoparticle in SF hydrogel. It was found that HAp nanoparticles were uniformly deposited on the pore wall of SF hydrogel. Structural characteristics of SF/HAp composite hydrogel was performed using X-ray diffraction and FT-IR analysis. It was found that β-sheet crystal conformation of SF was significantly influenced by the HAp content during gelation of a mixture of SF and HAp. As a result of MTT assay, the SF/HAp composite hydrogel showed excellent cell proliferation ability. Therefore, it is expected that SF hydrogel containing HAp nanoparticles has a high potential as bone regeneration scaffold.

Multiple strategies to activate gold nanoparticles as antibiotics

Widespread antibiotic resistance calls for new strategies. Nanotechnology provides a chance to overcome antibiotic resistance by multiple antibiotic mechanisms. This paper reviews the progress in activating gold nanoparticles with nonantibiotic or antibiotic molecules to combat bacterial resistance, analyzes the gap between experimental achievements and real clinical application, and suggests some potential directions in developing antibacterial nanodrugs.

Polymeric Hydrogels and Nanoparticles: A Merging and Emerging Field

Hydrogels have had extensive applications in scientific and industrial applications since their invention over 50 years ago. Responsive hydrogels based on temperature, light, and pH stimuli have been developed by changing the chemical components of the matrix structure. On the other hand, metallic nanoparticles of different shapes and sizes have been prepared by physical as well as chemical methods. These inorganic assemblies are currently widely used in the biomedical sciences and engineering fields. Recently, the combined use of hydrogels and nanoparticles in a single entity has gained enormous attention in areas such as catalysts, surface-enhanced Raman scattering, biosensors, and drug delivery. In this review, recent literature describing these technologies is summarized and an outlook on the promising future of this emerging field is provided.