Drug-Porous Silicon Dual Luminescent System for Monitoring and Inhibition of Wound Infection

Sensing patches for biomarker identification in skin-derived biofluids

In conventional clinical disease diagnosis and screening based on biomarker detection, most analysis samples are collected from serum, blood. However, these invasive collection methods require specific instruments, professionals, and may lead to infection risks. Additionally, the diagnosis process suffers from untimely results. The identification of skin-related biomarkers plays an unprecedented role in early disease diagnosis. More importantly, these skin-mediated approaches for collecting biomarker-containing biofluid samples are noninvasive or minimally invasive, which is more preferable for point-of-care testing (POCT). Therefore, skin-based biomarker detection patches have been promoted, owing to their unique advantages, such as simple fabrication, desirable transdermal properties and no requirements for professional medical staff. Currently, the skin biomarkers extracted from sweat, interstitial fluid (ISF) and wound exudate, are achieved with wearable sweat patches, transdermal MN patches, and wound patches, respectively. In this review, we detail these three types of skin patches in biofluids collection and diseases-related biomarkers identification. Patch classification and the corresponding manufacturing as well as detection strategies are also summarized. The remaining challenges in clinical applications and current issues in accurate detection are discussed for further advancement of this technology (Scheme 1).

Smart theranostics for wound monitoring and therapy

To overcome the challenges of poor wound diagnosis and limited clinical efficacy of current wound management, wound dressing materials with the aim of monitoring various biomarkers vital to the wound healing process such as temperature, pH, glucose concentration, and reactive oxygen species (ROS) and improving the therapeutic outcomes have been developed. These innovative theranostic dressings are smartly engineered using stimuli-responsive biomaterials to monitor and regulate local microenvironments and deliver cargos to the wound sites in a timely and effective manner. This review provides an overview of recent advances in novel theranostics for wound monitoring and therapy as well as giving insights into the future treatment of wounds via smart design of theranostic materials.

Portable Photoacoustic Analytical System Combined with Wearable Hydrogel Patch for pH Monitoring in Chronic Wounds

Timely diagnosis, monitoring, and management of chronic wounds play crucial roles in improving patients' quality of life, but clinical evaluation of chronic wounds is still ambiguous and relies heavily on the experience of clinician, resulting in increased social and financial burden and delay of optimal treatment. During the different stages of the healing process, specific and dynamic changes of pH values in the wound exudate can be used as biomarkers to reflect the wound status. Herein, a pH-responsive agent with well-behaved photoacoustic (PA) properties, nitrazine yellow (NY), was incorporated in poly(vinyl alcohol)/sucrose (PVA/Suc) hydrogel to construct a wearable pH-sensing patch (PVA/Suc/NY hydrogel) for monitoring of pH values during chronic wound healing. According to Rosencwaig-Gersho theory and the combination of 3D printing technology, the PA chamber volume and chopping frequency were systematically optimized to improve the sensitivity of the PA analytical system. The prepared PVA/Suc/NY hydrogel patch had excellent mechanical properties and flexibility and could maintain conformal contact with skin. Moreover, combined with the miniaturized PA analytical device, it had the potential to detect pH values (5.0-9.0) free from the color interference of blood and therapeutic drugs, which provides a valuable strategy for wound pH value monitoring by PA quantitation. This strategy of combining the wearable hydrogel patch with portable PA analysis offers broad new prospects for the treatment and management of chronic wounds due to its features of simple operation, time savings, and anti-interference.

Porous silicon-based sensing and delivery platforms for wound management applications

Wound management remains a great challenge for clinicians due to the complex physiological process of wound healing. Porous silicon (PSi) with controlled pore morphology, abundant surface chemistry, unique photonic properties, good biocompatibility, easy biodegradation and potential bioactivity represent an exciting class of materials for various biomedical applications. In this review, we focus on the recent progress of PSi in the design of advanced sensing and delivery systems for wound management applications. Firstly, we comprehensively introduce the common type, normal healing process, delaying factors and therapeutic drugs of wound healing. Subsequently, the typical fabrication, functionalization and key characteristics of PSi have been summarized because they provide the basis for further use as biosensing and delivery materials in wound management. Depending on these properties, the rise of PSi materials is evidenced by the examples in literature in recent years, which has emphasized the robust potential of PSi for wound monitoring, treatment and theranostics. Finally, challenges and opportunities for the future development of PSi-based sensors and delivery systems for wound management applications are proposed and summarized. We hope that this review will help readers to better understand current achievements and future prospects on PSi-based sensing and delivery systems for advanced wound management.

Wound pH-Modulating Strategies for Diabetic Wound Healing

Significance: Chronic diabetic wounds on the lower extremities (diabetic foot ulcers, DFU) are one of the most prevalent and life-threatening complications of diabetes, responsible for significant loss of quality of life and cost to the health care system. Available pharmacologic treatments fail to achieve complete healing in many patients. Recent studies and investigational treatments have highlighted the potential of modulating wound pH in DFU. Recent Advances: Data from in vitro, preclinical, and clinical studies highlight the role of pH in the pathophysiology of DFU, and topical administration of pH-lowering agents have shown promise as a therapeutic strategy for diabetic wounds. In this critical review, we describe the role of pH in DFU pathophysiology and present selected low-molecular-weight and hydrogel-based pH-modulating systems for wound healing and infection control in diabetic wounds. Critical Issues: The molecular mechanisms leading to pH alterations in diabetic wounds are complex and may differ between in vitro models, animal models of diabetes, and the human pathophysiology. Wound pH-lowering bandages for DFU therapy must be tested in established animal models of diabetic wound healing and patients with diabetes to establish a comprehensive benefit-risk profile. Future Directions: As our understanding of the role of pH in the pathophysiology of diabetic wounds is deepening, new treatments for this therapeutic target are being developed and will be tested in preclinical and clinical studies. These therapeutic systems will establish a target product profile for pH-lowering treatments such as an optimal pH profile for each wound healing stage. Thus, controlling wound bed pH could become a powerful tool to accelerate chronic diabetic wound healing.

Next-generation of smart dressings: Integrating multiplexed sensors and theranostic functions

Non-healing wounds represent a significant burden for healthcare systems and society, giving rise to severe economic and human issues. Currently, the use of dressings and visual assessment represent the primary and standard care for wounds. Conventional dressings, like cotton gauze, provide only passive physical protection. Besides, they end up paradoxically hampering the wound-healing process by producing tissue damage and pain when removed during routine check-ups. In response to these limitations, researchers, engineers, and technologists are developing innovative dressings that incorporate advanced diagnostic and therapeutic functionalities, coined as "smart dressings". Now, the maturation of smart dressing is bringing them closer to real-life applications, leading to an exciting new generation of these devices. The next generation of smart dressings is capable of monitoring in real-time multiple biomarkers while including pro-healing capabilities in a single platform. Such multiplexed and theranostic smart dressings are expected to offer a timely biomarker-directed diagnosis of non-healing wounds while enabling rapid, automated, and personalized treatments of infection and chronicity. Herein, we provide an insightful overview of these advantageous devices, delving into the diverse spectrum of possible engineering strategies. This encompasses the use of electrochemical and optical platforms with diverse multiplexing architectures, such as multi-zone sensing arrays and multi-layered devices. Open or closed-loop theranostic mechanisms using various stimuli-responsive materials that could be internally or externally controlled are also included. Finally, a critical discussion on the main challenges and future directions of smart dressings is also offered.

Tailored biomedical materials for wound healing

Wound healing is a long-term, multi-stage biological process that mainly includes haemostatic, inflammatory, proliferative and tissue remodelling phases. Controlling infection and inflammation and promoting tissue regeneration can contribute well to wound healing. Smart biomaterials offer significant advantages in wound healing because of their ability to control wound healing in time and space. Understanding how biomaterials are designed for different stages of wound healing will facilitate future personalized material tailoring for different wounds, making them beneficial for wound therapy. This review summarizes the design approaches of biomaterials in the field of anti-inflammatory, antimicrobial and tissue regeneration, highlights the advanced precise control achieved by biomaterials in different stages of wound healing and outlines the clinical and practical applications of biomaterials in wound healing.

Construction of lncRNA- and circRNA-associated ceRNA networks in the prostatic urethra of rats after simulating transurethral laser prostatectomy (TULP)

Non-coding RNA appears to be involved in wound repair. Competing endogenous RNA (ceRNA) appears to be an important post-transcriptional mechanism, it means that long noncoding RNA (lncRNA) or circular RNA (circRNA) acts as a microRNA (miRNA) sponge to further regulate mRNA. However, ceRNA network related to wound repair after prostatectomy has yet been constructed. TULP is the main surgical method of prostatectomy, but there have been no reports of TULP rat models in the past. We simulated TULP on rats, and observed the whole process of wound injury and repair after operation through pathological examination of wound tissue. Next, we discovered 732 differentially expressed lncRNAs (DElncRNAs), 47 differentially expressed circRNAs (DEcircRNAs), 17 differentially expressed miRNAs (DEmiRNAs), and 1892 differentially expressed mRNAs (DEmRNAs) related to wound repair after TULP through full transcriptome microarray and bioinformatics methods, and confirmed the reliability of transcriptome data by quantitative Reverse Transcription PCR (qRT-PCR), and immunohistochemistry. Then, we constructed the lncRNA- and circRNA-associated ceRNA regulatory networks related to wound repair after TULP in rats. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed that molecules in these networks were mainly involved in inflammatory infiltration, cell differentiation, and intercellular interactions and involved signal pathways such as the PI3K-Akt signaling pathway. Thus, this study successfully established the TULP model in rats, revealed potentially important biomarkers and ceRNA networks after prostatectomy in rats, and provided theoretical support for the repair of post-prostatectomy wound.

Particles-based medicated wound dressings: a comprehensive review

Wound healing is a dynamic process that is controlled by many factors. The interest in developing wound dressings capable of providing the required environment for the proper wound healing process is ever expanding, and particles occupy a sizable share of the research area. This comprehensive review reports 10 years of research in terms of current advances, delivery system evaluation, outcomes and future directions. The review follows a clearly defined method of article search and screening. Retrieved papers are reviewed regarding the materials, formulation development, and in vitro/in vivo testing of particles-based wound dressings. The review summarized the current status of medicated wound dressing research, identifies gaps to be addressed, and represents a reference for researchers working on wound dressings.

Current Progress and Outlook of Nano-Based Hydrogel Dressings for Wound Healing

Wound dressing is an important tool for wound management. Designing wound dressings by combining various novel materials and drugs to optimize the peri-wound environment and promote wound healing is a novel concept. Hydrogels feature good ductility, high water content, and favorable oxygen transport, which makes them become some of the most promising materials for wound dressings. In addition, nanomaterials exhibit superior biodegradability, biocompatibility, and colloidal stability in wound healing and can play a role in promoting healing through their nanoscale properties or as carriers of other drugs. By combining the advantages of both technologies, several outstanding and efficient wound dressings have been developed. In this paper, we classify nano-based hydrogel dressings into four categories: hydrogel dressings loaded with a nanoantibacterial drug; hydrogel dressings loaded with oxygen-delivering nanomedicines; hydrogel dressings loaded with nanonucleic acid drugs; and hydrogel dressings loaded with other nanodelivered drugs. The design ideas, advantages, and challenges of these nano-based hydrogel wound dressings are reviewed and analyzed. Finally, we envisaged possible future directions for wound dressings in the context of relevant scientific and technological advances, which we hope will inform further research in wound management.

Porous Silicon Carrier Endowed with Photothermal and Therapeutic Effects for Synergistic Wound Disinfection

Drug carriers endowed with photothermal effects will allow the drug delivery system to release drugs in a thermal-stimuli manner. In addition, the photothermal therapy (PTT) will also interplay with therapeutic drugs loaded in the carrier to exhibit synergistic bioactivity for various disease treatment. However, endowing the drug carrier with photothermal and synergistic therapeutic effects still has challenge. Herein, we demonstrate that surface modification of porous silicon (PSi) with polydopamine (PDA) could endow the classical drug carrier with a significant photothermal effect for advanced antibacterial therapy and wound disinfection. Specifically, the PSi surface interacts with a Cu²⁺/PDA complex via a simple and fast surface reduction-induced deposition method, forming the unique CuPDA coated PSi microcarrier (CuPPSi) without blocking the mesoporous structure. The CuPPSi carrier generates a higher near-infrared (NIR) photothermal efficiency and improved drug loading capacity owing to the abundant functional groups of PDA. Stimuli-responsive release of antibacterial Cu²⁺ and loaded curcumin (Cur) from CuPPSi can be realized under multiple stimuli including pH, reactive oxygen species and NIR laser irradition. Benefited from the carrier's intrinsic multimodal therapy, the CuPPSi-Cur platform exhibits amplified, broad-spectrum, and synergistic antibacterial effect, killing more than 98% for both Staphylococcus aureus and Escherichia coli at a mild PTT temperature (∼45 °C). Notably, the combined therapy promotes migration of fibroblasts with no significant cytotoxicity as revealed through cell experiments in vitro. In bacteria-infected mice model, efficient bacterial ablation and wound healing are further demonstrated with negligible side effects in vivo. Overall, the rational design of a drug carrier with photothermal and therapeutic effects provides a novel intervention for amplifing wound disinfection clinically.

Next-Generation Diagnostic Wound Dressings for Diabetic Wounds

Chronic lower extremity wounds (diabetic foot ulcers) are a serious and prevalent complication of diabetes. These wounds exhibit low healing rates and present a high risk of amputation. Current diagnostic options for foot ulcers are limited to macroscopic wound analysis such as wound depth, implicated tissues, and infection. Molecular diagnostics promises to improve foot ulcer diagnosis, staging, and assessment of the treatment response. In this perspective, we report recent progress in understanding the pathophysiology of diabetic wound healing and point to recently emerged novel molecular targets for wound diagnostics. We discuss selected diagnostic wound dressings under preclinical development that detect one or several inflammatory markers, bacterial secretions, hyperglycemia, and mechanical stress. We also highlight key translational challenges of investigational diagnostic bandages for diabetic foot ulcers.

Enteric Polymer-Coated Porous Silicon Nanoparticles for Site-Specific Oral Delivery of IgA Antibody

Porous silicon (pSi) nanoparticles are loaded with Immunoglobulin A-2 (IgA2) antibodies, and the assembly is coated with pH-responsive polymers on the basis of the Eudragit family of enteric polymers (L100, S100, and L30-D55). The temporal release of the protein from the nanocomposite formulations is quantified following an in vitro protocol simulating oral delivery: incubation in simulated gastric fluid (SGF; at pH 1.2) for 2 h, followed by a fasting state simulated intestinal fluid (FasSIF; at pH 6.8) or phosphate buffer solution (PBS; at pH 7.4). The nanocomposite formulations display a negligible release in SGF, while more than 50% of the loaded IgA2 is released in solutions at a pH of 6.8 (FasSIF) or 7.4 (PBS). Between 21 and 44% of the released IgA2 retains its functional activity. A capsule-based system is also evaluated, where the IgA2-loaded particles are packed into a gelatin capsule and the capsule is coated with either EudragitL100 or EudragitS100 polymer for a targeted release in the small intestine or the colon, respectively. The capsule-based formulations outperform polymer-coated nanoparticles in vitro, preserving 45-54% of the activity of the released protein.

Silicon-Based Scaffold for Wound Healing Skin Regeneration Applications: A Concise Review

Silicon has made its breakthrough in various industries, including clinical and biomedical applications. Silicon-based biomaterials that were fabricated into various types of scaffolds may attract interest due to their highly favorable properties covering their excellent biocompatibility, high surface area, mechanical strength, and selectivity depending on their application including film, hydrogel, nanoparticles, and so on. Silicon-based materials have also shown exciting results involving cell culture, cell growth, as well as tissue engineering. In this article, a simple review compromising the evaluation of silicon's unique properties has been discussed and followed by the application of the silicone-based product in future perspectives in biomedical fields. The review goals are to widen and inspire broader interest in silicone-based materials in wound healing research.

Overcoming Methicillin-Resistance Staphylococcus aureus (MRSA) Using Antimicrobial Peptides-Silver Nanoparticles

Antibiotics are regarded as a miracle in the medical field as it prevents disease caused by pathogenic bacteria. Since the discovery of penicillin, antibiotics have become the foundation for modern medical discoveries. However, bacteria soon became resistant to antibiotics, which puts a burden on the healthcare system. Methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most prominent antibiotic-resistant bacteria in the world since 1961. MRSA primarily developed resistance to beta-lactamases antibiotics and can be easily spread in the healthcare system. Thus, alternatives to combat MRSA are urgently required. Antimicrobial peptides (AMPs), an innate host immune agent and silver nanoparticles (AgNPs), are gaining interest as alternative treatments against MRSA. Both agents have broad-spectrum properties which are suitable candidates for controlling MRSA. Although both agents can exhibit antimicrobial effects independently, the combination of both can be synergistic and complementary to each other to exhibit stronger antimicrobial activity. The combination of AMPs and AgNPs also reduces their own weaknesses as their own, which can be developed as a potential agent to combat antibiotic resistance especially towards MRSA. Thus, this review aims to discuss the potential of antimicrobial peptides and silver nanoparticles towards controlling MRSA pathogen growth.

Wound Dressing: From Nanomaterials to Diagnostic Dressings and Healing Evaluations

Wound dressings based on nanomaterials play a crucial role in wound treatment and are widely used in a whole range of medical settings, from minor to life-threatening tissue injuries. This article presents an educational review on the accumulating knowledge in this multidisciplinary area to lay out the challenges and opportunities that lie ahead and ignite the further and faster development of clinically valuable technologies. The review analyzes the functional advantages of nanomaterial-based gauzes and hydrogels as well as hybrid structures thereof. On this basis, the review presents state-of-the-art advances to transfer the (semi)blind approaches to the evaluation of a wound state to smart wound dressings that enable real-time monitoring and diagnostic functions that could help in wound evaluation during healing. This review explores the translation of nanomaterial-based wound dressings and related medical aspects into real-world use. The ongoing challenges and future opportunities associated with nanomaterial-based wound dressings and related clinical decisions are presented and reviewed.

Degradable and self-luminescence porous silicon particles as tissue adhesive for wound closure, monitoring and accelerating wound healing

Tissue adhesives have received much attention for their effectiveness in sealing wounds or incisions in clinical surgery, especially in minimally invasive surgery. To meet the safe and smart wound management requirements, ideal tissue adhesives are expected to have high biocompatibility, and be able to accelerate wound closing and healing, and monitor wound healing process. However, few adhesives fit all of the above descriptions. It has been demonstrated that inorganic nanoparticles can directly glue biological tissue based on nano-bridging effect. In this study, self-luminescence porous silicon (LPSi) particles were prepared with degradable and biocompatible properties. In addition, the self-luminescence property of LPSi particles was discovered by In Vivo Imaging System (IVIS) for the first time, which can avoid the limitations of photoluminescence imaging. Due to the oxidation and degradation reaction, LPSi particles not only can be degraded completely in several days, but also showed satisfactory biocompatibility. And their degradation product could promote tube formation of HUVECs. Moreover, owing to the high specific surface area and the outer oxide layer of LPSi particles, LPSi tissue adhesive exhibited strong adhesive strength to pig livers. Furthermore, this adhesive closed wound rapidly, promoted angiogenesis and epidermal regeneration, and facilitated wound healing in a mouse skin incision model. Importantly, the wound healing ratio can be monitored by measuring the self-luminescence intensity of LPSi particles in the wound site. This study reveals that LPSi particles could be employed as a safe and smart wound management tissue adhesive for wound closure, as well as accelerating and monitoring wound healing.

Graphene quantum dot-decorated luminescent porous silicon dressing for theranostics of diabetic wounds

Diabetic wound healing is highly desirable but remains a great challenge owing to the continuous damage of excess reactive oxygen species (ROS) and degradation of therapeutic peptide drugs by over-expressed matrix metalloproteinase (MMP). Herein, we developed a stimuli-responsive smart dressing for theranostics of diabetic wounds using graphene quantum dots-decorated luminescent porous silicon (GQDs@PSi), which was further loaded with peptide and embedded in chitosan (CS) film. The confinement of GQDs in nanochannels of PSi endowed GQDs@PSi with efficient fluorescence resonance energy transfer (FRET) effect, leading to initial red fluorescence of PSi with complete quench of GQD's blue fluorescence. Furthermore, the decoration of GQDs on PSi surface significantly enhanced the loading capacity for peptide drugs including epidermal growth factor (EGF) and insulin (Ins) which can promote diabetic wounds healing. The peptides coloaded in GQDs@PSi exhibited sustained release behavior and could be protected in presence of MMP owing to size exclusion of PSi's nanochannels. As H₂O₂-triggered oxidation of PSi lead to weakened FRET effect and degradation of PSi, GQDs@PSi demonstrated H₂O₂-responsive ratiometric fluorescence change (from red PSi to blue GQDs) and drug release behavior. In combination with CS's degradation in the acidic and oxidation microenvironment, the smart dressing also showed stimuli-responsive drug release toward slightly acid and highly oxidative conditions in diabetic wounds. In vitro and in vivo results demonstrated the smart dressing enhanced the proliferation and migration of cells as well as significantly healed diabetic wounds. Real-time indicating of the exacerbation or healing of diabetic wounds was also realized using the rate of fluorescent discoloration of the dressing. STATEMENT OF SIGNIFICANCE: In this work, a dual luminescent nanomaterial was created by hosting graphene quantum dots (GQDs) in the nanochannel of porous silicon (PSi), which was further applied for theranostics of diabetic wound. The synergistic effect of the host-guest nanohybrid is significant. The GQDs can significantly improve the capacity for peptide drug loading and form a stimuli-response visual ratiometric sensor with luminescent PSi, which can also protect and sustain release of peptide drugs for effective diabetic wounds treatment. After embedded in a chitosan film, the smart dressing displayed H₂O₂-responsive visual ratiometric fluorescence change and drug release behavior. In vitro and in vivo results demonstrated the smart dressing enhanced the proliferation and migration of cells as well as significantly healed diabetic wounds.

Anti-Sandwich Structured Photo-Electronic Wound Dressing for Highly Efficient Bacterial Infection Therapy

Photo-electronic devices based on reactive oxygen species (ROS) generation suffer a crucial limitation in wound treatment due to their sandwich structure, which prevents the contact of ROS with wound tissue. In this work, the first anti-sandwich structured visible-light/electricity dual-responsive wound dressing is constructed for treatment of methicillin-resistant Staphylococcus aureus (MRSA), based on selenoviologen-appendant polythiophene (SeV²⁺ -PT)-containing polyacrylamide hydrogels. The new wound dressing is named an anti-sandwich structured photo-electronic wound dressing (PEWD). The unique structure of PEWD enables its use in synergistic electrodynamic and photodynamic therapy (EDT and PDT), providing rapid, on-demand, and sustained generation of ROS in situ via short-time light irradiation and/or wireless-controlled electrification. The PEWD possesses good flexibility, excellent biocompatibility, and fast response, as well as sustained ROS generation in a physiological environment. Animal experiments demonstrate effective ROS generation in 6 s under irradiation and electrification, inhibiting infection at an early stage, and substantially shortening the healing time of bacterial infection (to within 7 days). This proof-of-concept research holds great promise in developing new flexible PEWD, and novel strategies to improve wound treatment.

Small-volume detection: platform developments for clinically-relevant applications

Biochemical analysis of human body fluids is a frequent and fruitful strategy for disease diagnosis. Point-of-care (POC) diagnostics offers the tantalizing possibility of providing rapid diagnostic results in non-laboratory settings. Successful diagnostic testing using body fluids has been reported on in the literature; however, small-volume detection devices, which offer remarkable advantages such as portability, inexpensiveness, capacity for mass production, and tiny sample volume requirements have not been thoroughly discussed. Here, we review progress in this research field, with a focus on developments since 2015. In this review article, we provide a summary of articles that have detailed the development of small-volume detection strategies using clinical samples over the course of the last 5 years. Topics covered include small-volume detection strategies in ophthalmology, dermatology or plastic surgery, otolaryngology, and cerebrospinal fluid analysis. In ophthalmology, advances in technology could be applied to examine tear or anterior chamber (AC) fluid for glucose, lactoferrin, interferon, or VEGF. These approaches could impact detection and care for diseases including diabetic mellitus, dry-eye disease, and age-related maculopathy. Early detection and easy monitoring are critical approaches for improving overall care and outcome. In dermatology or plastic surgery, small-volume detection strategies have been applied for passive or interactive wound dressing, wound healing monitoring, and blister fluid analysis for autoimmune disease diagnosis. In otolaryngology, the analysis of nasal secretions and mucosa could be used to differentiate between allergic responses and infectious diseases. Cerebrospinal fluid analysis could be applied in neurodegenerative diseases, central neural system infection and tumor diagnosis. Other small-volume fluids that have been analyzed for diagnostic and monitoring purposes include semen and cervico-vaginal fluids. We include more details regarding each of these fluids, associated collection and detection devices, and approaches in our review.

Synergistic and On-Demand Release of Ag-AMPs Loaded on Porous Silicon Nanocarriers for Antibacteria and Wound Healing

Due to the abuse of antibiotics, antimicrobial resistance is rapidly emerging and becoming a major global risk for public health. Thus, there is an urgent need for reducing the use of antibiotics, finding novel treatment approaches, and developing controllable release systems. In this work, a dual synergistic antibacterial platform with on-demand release ability based on silver nanoparticles (AgNPs) and antimicrobial peptide (AMP) coloaded porous silicon (PSi) was developed. The combination of AgNPs and AMPs (Tet-213, KRWWKWWRRC) exhibited an excellent synergistic antibacterial effect. As a carrier, porous silicon can efficiently load AgNPs and AMP under mild conditions and give the platform an on-demand release ability and a synergistic release effect. The AgNPs and AMP coloaded porous silicon microparticles (AgNPs-AMP@PSiMPs) exhibited an acid pH and reactive oxygen species (ROS)-stimulated release of silver ions (Ag⁺) and AMPs under bacterial infection conditions because of oxidation and desorption effects. Moreover, the release of the bactericide could be promoted by each other due to the interplay between AgNPs and Tet-213. In vitro antibacterial tests demonstrated that AgNPs-AMP@PSiMPs inherited the intrinsic properties and synergistic antibacterial efficiency of both bactericides. In addition, wound dressing loaded with AgNPs-AMP@PSiMPs showed outstanding in vivo bacteria-killing activity, accelerating wound-healing, and low biotoxicity in aStaphylococcus aureus-infected rat wound model. The present work demonstrated that PSiMPS might be an efficient platform for loading the antibiotic-free bactericide, which could synergistically and on-demand release to fight wound infection and promote wound healing.

A co-delivery platform for synergistic promotion of angiogenesis based on biodegradable, therapeutic and self-reporting luminescent porous silicon microparticles

Insufficient angiogenesis happened in body defects such as ulceration, coronary heart disease, and chronic wounds constitutes a major challenge in tissue regeneration engineering. Owing to the poor bioactivity and maintenance of pro-angiogenic cells and factors during transplantation, new bioactive materials to tackle the barrier are highly desirable. Herein, we demonstrate a co-delivery platform for synergistic promotion of angiogenesis based on biodegradable, therapeutic, and self-reporting luminescent porous silicon (PSi) microparticles. The biodegradable and biocompatible PSi microparticles could quickly release therapeutic Si ions, which is bioactive to promote cell migration, tube formation, and angiogenic gene expression in vitro. To construct a highly efficient angiogenesis treatment platform, vascular endothelial growth factor (VEGF) was electrostatically adsorbed by PSi microparticles for effective drug loading and delivery. The dual therapeutic components (Si ions and VEGF) could release with the dissolution of Si skeleton, accompanying by the decay of photoluminescence (PL) intensity and blue shift of the maximum PL wavelength. Therefore, real-time drug release could be self-reported and assessed with the two-dimensional PL signal. The co-delivery of Si ions and VEGF displayed synergistic effect and highly efficient angiogenesis, which was evidenced by the enhancement of endothelial cell migration and tube formation in vitro with approximately 1.5-5 times higher than control. The blood vessel formation in vivo was also significantly improved as shown by the chick chorioallantoic membrane (CAM) model, in which the total length, size and junctions exhibited 2.1 ± 0.4, 4 ± 0.4, and 3.9 ± 0.3 times in comparison to control, respectively. The PSi and VEGF co-delivery system display great potential in tissue engineering as a biodegradable and self-reporting theranostic platform to promote angiogenesis.

A visible-light-excitable mitochondria-targeted europium complex probe for hypochlorous acid and its application to time-gated luminescence bioimaging

Development of fluorescent/luminescent probes for rapid, selective and sensitive detection of reactive oxygen species (ROS) is of great significance for understanding the roles of ROS in pathophysiological processes. In the present research, a visible-light-excitable Eu³⁺ complex-based probe, Eu(L)₃(DPBT), is designed and synthesized for the time-gated luminescence (TGL) determination of hypochlorous acid (HClO) in vitro and in vivo. The proposed probe exhibits a rapid, selective and sensitive TGL response to HClO, and excellent localization of mitochondria in living cells with low cytotoxicity. These features allow the probe to be used for the TGL sensing and imaging of HClO formation in mimic inflammatory cells at a subcellular level, as well as in endotoxin-induced liver injury and rheumatoid arthritis in live mice. In addition, by immobilizing the probe in the PEG hydrogel, the smart sensor films with rapid response to HClO were prepared, and successfully used for the real-time monitoring of HClO generation in mouse wounds, in order to distinguish the infected wounds from acute ones. Overall, this study provides a useful tool for the clinical monitoring and treatment of wound diseases.

Materiales sensibles a biomarcadores y apósitos inteligentes: revisión sistemática

OBJECTIVE

Evaluate a number of biomarkers that can objectively measure the wound healing process, and identify the materials that could replicate this in smart wound dressings.

METHOD

A systematic review was conducted to establish the use of materials sensitive to biomarkers. Publications in English were included. Review articles and abstracts presented at conferences were excluded.

RESULTS

A total of 296 studies were identified, of which 19 were included. All of these were experimental studies. The articles evaluated pH, temperature, blood pressure, uric acid, and glucose. The materials used were hydrogels, fibres and conductive inks.

CONCLUSION

The most cited biomarker was pH. Materials that evaluate biomarkers via colorimetric methods could be the most suitable to incorporate into smart wound dressings.

A smart and active film with tunable drug release and color change abilities for detection and inhibition of bacterial growth

Antimicrobial resistance has become a global issue and thus the development of natural products/biomedical materials composites with antibacterial activities is urgently needed. When acute wounds develop into chronic wounds, the wound environments become alkaline. As long as infections occur, the wound pH further increases, making the wounds difficult to heal. Besides, bacterial growth in poultry, meat, fish and seafood products is usually reflected in a marked increase of pH values. Herein, smart, stimuli responsive self-assembled multilayer and complex film were constructed through the formation of hydrogen bonds and hydrophobic interactions between hydroxypropyl methylcellulose (HPMC) and epigallocatechin-3-gallate (EGCG), thereby greatly reducing the hydrophilicity of HPMC and offering enhanced mechanical strength, superior free radical scavenging capability, and improved water vapor and light barrier properties. The EGCG/HPMC complex film was able to control EGCG release by tuning pH or temperature of the release medium. Furthermore, incorporation of CuS nanoparticles into the film allowed it to triggers EGCG release in an on-demand fashion under near-infrared (NIR) exposure. Bacterial growth in glucose-free nutrient broth medium caused pH to rise (near pH 8.0), leading to transformation of EGCG from phenol type to phenolate ion and then quinone, allowing for spontaneous generation of H₂O₂ to kill bacteria. The complex films changed their color in response to bacterial growth because EGCG transformed from phenol type to quinone type under alkaline condition. The green synthesized EGCG/HPMC complex films can be used as a colorimetric pH indicator and an antibacterial material for wound dressing and food packaging applications.

Honokiol-mesoporous Silica Nanoparticles Inhibit Vascular Restenosis via the Suppression of TGF-β Signaling Pathway

Introduction

The main pathological mechanism of restenosis after percutaneous coronary intervention (PCI) is intimal hyperplasia, which is mainly caused by proliferation and migration of vascular smooth muscle cells (VSMCs). Our previous study found that honokiol (HNK), a small-molecule polyphenol, can inhibit neointimal hyperplasia after balloon injury, but its specific mechanism is still unclear. Moreover, poor water solubility as well as low bioavailability of honokiol has limited its practical use.

Methods

We used mesoporous silica nanoparticles (MSNPs) as a standard substance to encapsulate HNK and then assemble into honokiol-mesoporous silica nanoparticles, and we investigated the effect of these nanoparticles on the process of restenosis after common carotid artery injury in rats.

Results

We report a promising delivery system that loads HNK into MSNPs and finally assembles it into a nanocomposite particle. These HNK-MSNPs not merely inhibited proliferation and migration of VSMCs by reducing phosphorylation of Smad3, but also showed a higher suppression of intimal thickening than the free-honokiol-treated group in a rat model of balloon injury.

Conclusion

To sum up, this drug delivery system supplies a potent nano-platform for improving the biological effects of HNK and provides a promising strategy for preventing vascular restenosis.

Ratiometric Fluorescent Nanohybrid for Noninvasive and Visual Monitoring of Sweat Glucose

Noninvasive and visual monitoring of glucose is highly desirable for diabetes diagnostics and long-term home-based health management. Owing to the correlation of the glucose level between blood and sweat, on-body sweat glucose detection provides potential for noninvasive healthcare but is highly challenging. Herein, we for the first time demonstrate a wearable skin pad based on the ratiometric fluorescent nanohybrid, which can realize noninvasive and visual monitoring of sweat glucose. Luminescent porous silicon (PSi) particles, which have a porous structure and oxidation-responsive photoluminescence decay, are chosen to load (adsorb or entrap) carbon quantum dots (CQDs) for the construction of the dual fluorescence nanohybrid. Bimetallic (Au and Ag) nanoparticles (BiM) are also co-decorated on the PSi particle to improve detection sensitivity by enhancing PSi's initial fluorescence and oxidation kinetics. Owing to the efficient fluorescence resonance energy transfer effect, BiM-CQDs@PSi initially exhibits PSi's red fluorescence with complete quenching of CQDs's blue fluorescence. The oxidation of PSi triggered by hydrogen peroxide (H₂O₂) weakens the FRET effect and decays PSi's fluorescence, causing ratiometric fluorescence to change from red (PSi) to blue (CQDs). A wearable skin pad is easily fabricated by co-immobilization of BiM-CQDs@PSi and glucose oxidase (GOX) in a transparent and biocompatible chitosan film supported by an adhesive polyurethane membrane. When the skin pad is attached on the body, the same ratiometric fluorescence transition (red → blue) is observed upon the stimulation of H₂O₂ generated in GOX-catalyzed oxidation of sweat glucose. Based on the strong correlation between the ratio of the fluorescence change and sweat glucose level, clinical tests toward diabetics and healthy volunteers can clearly indicate hyperglycemia.

Nanoparticle-Based Wound Dressing: Recent Progress in the Detection and Therapy of Bacterial Infections

Bacterial infections in wounds often delay the healing process, and may seriously threaten human life. It is urgent to develop wound dressings to effectively detect and treat bacterial infections. Nanoparticles have been extensively used in wound dressings because of their specific properties. This review highlights the recent progress on nanoparticle-based wound dressings for bacterial detection and therapy. Specifically, nanoparticles have been applied as intrinsic antibacterial agents or drug delivery vehicles to treat bacteria in wounds. Moreover, nanoparticles with photothermal or photodynamic property have also been explored to endow wound dressings with significant optical properties to further enhance their bactericidal effect. More interestingly, nanoparticle-based smart dressings have been recently explored for bacteria detection and treatment, which enables an accurate assessment of bacterial infection and a more precise control of on-demand therapy.

Nanomaterials for Nanotheranostics: Tuning Their Properties According to Disease Needs

Nanotheranostics is one of the biggest scientific breakthroughs in nanomedicine. Most of the currently available diagnosis and therapies are invasive, time-consuming, and associated with severe toxic side effects. Nanotheranostics, on the other hand, has the potential to bridge this gap by harnessing the capabilities of nanotechnology and nanomaterials for combined therapeutics and diagnostics with markedly enhanced efficacy. However, nanomaterial applications in nanotheranostics are still in its infancy. This is due to the fact that each disease has a particular microenvironment with well-defined characteristics, which promotes deeper selection criteria of nanomaterials to meet the disease needs. In this review, we have outlined how nanomaterials are designed and tailored for nanotheranostics of cancer and other diseases such as neurodegenerative, autoimmune (particularly on rheumatoid arthritis), and cardiovascular diseases. The penetrability and retention of a nanomaterial in the biological system, the therapeutic strategy used, and the imaging mode selected are some of the aspects discussed for each disease. The specific properties of the nanomaterials in terms of feasibility, physicochemical challenges, progress in clinical trials, its toxicity, and their future application on translational medicine are addressed. Our review meticulously and critically examines the applications of nanotheranostics with various nanomaterials, including graphene, across several diseases, offering a broader perspective of this emerging field.

Smart wound dressing for infection monitoring and NIR-triggered antibacterial treatment

Hydrogel-based wound dressings can monitor infection via pH-responsive FRET changes and provide on-demand antibacterial treatment via NIR-triggered antibiotic release.

Hierarchical Nanostructuring of Porous Silicon with Electrochemical and Regenerative Electroless Etching

Hierarchically nanostructured silicon was produced by regenerative electroless etching (ReEtching) of Si powder made from pulverized anodized porous silicon. This material is characterized by ∼15 nm mesopores, into the walls of which tortuous 2-4 nm pores have been introduced. The walls are sufficiently narrow that they support quantum-confined crystallites that are photoluminescent. With suitable parameters, the ReEtching process also provides control over the emission color of the photoluminescence. Ball milling and hydrosilylation of this powder with undecylenic acid produces nanoparticles with hydrodynamic diameter of ∼220 nm that exhibit robust and bright luminescence that can be excited with either one ultraviolet/visible photon or two near-infrared photons. The long-lived, robust visible photoluminescence of these chemically passivated porous silicon nanoparticles is well-suited for bioimaging and theranostic applications.

Quantum Ensembles of Silicon Nanoparticles: Discrimination of Static and Dynamic Photoluminescence Quenching Processes

Porous silicon photoluminescence is characterized by a broad emission band that displays unusually long (tens to hundreds of micro-seconds), wavelength-dependent emissive lifetimes. The photoluminescence is associated with quantum confinement of excitons in silicon nanocrystallites contained within the porous matrix, and the broad emission spectrum derives from the wide distribution of nanocrystallite sizes in the material. The longer emissive lifetimes in the ensemble of quantum-confined emitters correspond to the larger nanocrystallites, with their longer wavelengths of emission. The quenching of this photoluminescence by aromatic, redox-active molecules aminochrome (AMC), dopamine, adrenochrome, sodium anthraquinone-2-sulfonate, benzyl viologen dichloride, methyl viologen dichloride hydrate, and ethyl viologen dibromide is studied, and dynamic and static quenching mechanisms are distinguished by the emission lifetime analysis. Because of the dependence of the emission lifetime on emission wavelength from the silicon nanocrystallite ensemble, a pronounced blue shift is observed in the steady-state emission spectrum upon exposure to dynamic-type quenchers. Conversely, static-type quenching systems show uniform quenching across all emission wavelengths. Thus, the difference between static and dynamic quenching mechanisms is readily distinguished by ratiometric photoluminescence spectroscopy. The application of this concept to imaging of AMC, the oxidized form of the neurotransmitter dopamine that is of interest for its role in neurodegenerative diseases, is demonstrated. It is found that static electron acceptors result in no ratiometric contrast, while AMC shows a strong contrast, allowing ready visualization in a 2-D imaging experiment.

Emerging vistas in theranostic medicine

Recent years have witnessed a paradigm shift in the focus of healthcare towards development of customized therapies which cater to the unmet needs in a myriad of disease areas such as cancer, infections, cardiovascular diseases, neurodegenerative disorders and inflammatory disorders. The term 'theranostic' refers to such multifunctional systems which combine the features of diagnosis and treatment in a single platform for superior control of the disease. Theranostic systems enable detection of disease, treatment and real time monitoring of the diseased tissue. Theranostic nanocarriers endowed with multiple features of imaging, targeting, and providing on-demand delivery of therapeutic agents have been designed for enhancement of therapeutic outcomes. Fabrication of theranostics involves utilization of materials having distinct properties for imaging, targeting, and programming drug release spatially and temporally. Although the field of theranostics has been widely researched and explored so far for treatment of different types of cancer, there have been considerable efforts in the past few years to extend its scope to other areas such as infections, neurodegenerative disorders and cardiovascular diseases. This review showcases the potential applications of theranostics in disease areas other than cancer. It also highlights the cardinal issues which need to be addressed for successful clinical translation of these theranostic tools.

A Gold/Silver Hybrid Nanoparticle for Treatment and Photoacoustic Imaging of Bacterial Infection

Ag+ ions are a well-known antibacterial agent, and Ag nanoparticles act as a reservoir of these Ag+ ions for targeted therapy of bacterial infections. However, there are no tools to effectively trigger and monitor the release of Ag+ ions from Ag nanoparticles. Photoacoustic (PA) imaging is an emerging noninvasive imaging tool, and gold nanorods (AuNRs) are an excellent contrast agent for PA imaging. In this work, we developed Au/Ag hybrid nanoparticles by coating AuNRs with silver (Ag), which decreased their photoacoustic signal. The as-prepared, Ag-coated Au nanorods (Au/AgNRs) are stable under ambient conditions, but the addition of ferricyanide solution (1 mM) results in oxidative etching of the silver shell. The PA contrast is simultaneously recovered as the silver is released, and this PA signal offers noninvasive monitoring of localized release of Ag+ ions. The released Ag+ ions exhibit a strong bactericidal efficacy similar to equivalent free Ag+ ions (AgNO3), and the nanoparticles killed >99.99% of both (Gram-positive) methicillin-resistant Staphylococcus aureus (MRSA, 32 μM Ag+ equivalent) and (Gram-negative) Escherichia coli (8 μM Ag+ equivalent). The theranostic potential of these nanoparticles was demonstrated in a pilot in vivo study. Mice were inoculated with MRSA and Au/AgNRs were subcutaneously implanted followed by silver etching. There was a 730% increase in the PA signal ( p < 0.01) pre- and post-etching, and the bacterial counts in infected tissues of the treated group were reduced by 1000-fold (log CFU/g = 4.15 vs 7.75) versus the untreated control; this treatment efficacy was confirmed with histology. We further showed that these hybrid nanoparticles could release Ag+ after stimulation by reactive oxygen species including hydrogen peroxide and peroxynitrite. These hybrid Au/Ag nanoparticles are a useful theranostic agent for the photoacoustic imaging and treatment of bacterial infections.