ACS Applied Materials & Interfaces

Carbon quantum dots derived from mango leaves exhibited bright red fluorescence. These negatively charged particles underwent coating with the positively charged lipid molecule N-[1-(2,3-dioleyloxy) propyl]-N,N,N-trimethylammonium chloride (DOTMA). However, the bioconjugate displayed reduced uptake compared to the standalone mQDs in cancer cells (SUM 159A), and increased uptake in the case of epithelial (RPE-1) cells. Upon in vitro testing, the bioconjugate demonstrated a mitigating effect on the individual toxicity of both DOTMA and mQDs in SUM-159A (cancerous cells) and of DOTMA in RPE-1 cells. Conversely, it exhibited a proliferative effect on RPE-1 (epithelial cells). Surface modifications of QDs with lipids thus enhances their compatibility with biological systems, reducing systemic toxicity, minimizing off-site effects, sustaining drug release, and modulating cellular viability through various mechanisms (for example, apoptosis), which is, therefore, crucial for multiple applications such as targeted therapeutics. TOC O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=150 SRC="FIGDIR/small/587464v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1eca201org.highwire.dtl.DTLVardef@7ff0a3org.highwire.dtl.DTLVardef@18f89b2org.highwire.dtl.DTLVardef@993b42_HPS_FORMAT_FIGEXP M_FIG C_FIG Red emitting, fluorescent carbon quantum dots synthesized using mango leaves(mQDs) showed enhanced cellular uptake and reduced cell viability in the case of cancer cells when compared with lipid-coated mQDs. However, in the case of non-cancerous cells, the lipid-coated mQDs showed enhanced cellular uptake and cell viability when compared with mQDs alone.

Although electrostatic modification of bacterial surfaces using polyelectrolytes (PEs) is a convenient and versatile tool for biotechnological processes, the ambiguities in toxicity of PEs between various bacteria and the insufficient understanding of the mechanism of action of cationic PEs and their nano-thick shells formed around the bacteria create a bottleneck of the approach. Here, we show how the viability of two bacterial strains, Escherichia coli and Pseudomonas stutzeri, both from the Gram-negative group differs, when the cells are exposed to cationic PEs under different conditions. Although the cell wall architecture of the strains should be structurally similar, we found that the viability of E. coli was not affected by the electrostatic deposition of polyethyleneimine (PEI) or poly(allylamine) hydrochloride (PAH), whereas for P. stutzeri the deposition resulted in high death rates. The cells of E. coli proved to be suitable templates for Layer-by-Layer (LbL) modification, while in P. stutzeri a modified protocol with mild conditions had to be used to ensure the viability of the cells. Super resolution stimulated emission depletion (STED) microscopy allowed us to clearly visualize that after PE deposition onto the surface of the cells, the PEs could penetrate inside the cells of P. stutzeri, while forming a capsule around E. coli as expected. Therefore, this knowledge will help us select the most appropriate combinations of strains and PEs, for biotechnological processes or biomedical application, preventing unwanted toxicity.

Towards the goal of developing bio-chip / lab-on-a-chip substrates capable of performing highly specific bio-chemical reactions, Neutravidin binding to mixed Biotinylated Silane Self-Assembled Monolayers were studied using Confocal Fluorescence Light Microscopy. Non-specific bindings, specifically the formations of Neutravidin clusters, were quantified. Several experiments were conducted to determine the concentrations of Neutravidin necessary to not saturate surface binding to Biotinylated Self-Assembled Monolayers, determine the effectiveness of using FBS blocking buffers to reduce non-specific binding, optimize the repeatability of Neutravidin binding to Biotinlyated mixed Self-Assembled Monolayers with Silane-PEG-Biotin compositions ranging from 0 to 15%, and quantify background Neutravidin bindings and the corresponding formations of Neutravidin clusters to Self-Assembled Monolayers as Silane-PEG-Biotin percent compositions increase from 0 to 15%. The Neutravidin, Silane-PEG-Biotin, and Silane mPEG concentrations and ratios needed to develop homogeneous Neutravidin films, without the formations of clusters, on the Self-Assembled Monolayers have been determined.

One of the crucial requirements of quantum dots for biological applications is their surface modifications for very specific and enhanced biological recognition and uptake. Toward this, we present the green synthesis of bright, red-emitting carbon quantum dots derived from mango leaf extract (mQDs). These mQDs are conjugated electrostatically with dopamine to form mQDs-dopamine (mQDs: DOPA) bioconjugates. Bright red fluorescence of mQDs was used for bioimaging and uptake in multiple cell lines, tissues, and in vivo models like zebrafish. mQDs exhibited the highest uptake in brain tissue as compared to others. mQD:DOPA conjugate induced cellular toxicity only in cancer cells while showing increased uptake in epithelial cells and zebrafish. Additionally, the mQDs: DOPA promoted neuronal differentiation of SH-SY5Y cells to complete neurons. Both mQDs and mQDs: DOPA exhibited potential for higher collective cell migrations implicating their future potential as next-generation tools for advanced biological and biomedical applications. TOCmQDs were electrostatically conjugated with dopamine (DOPA) to form the mQDs: DOPA bioconjugate. mQDs are used to image cells, tissues, and zebrafish embryos. mQDs: DOPA kills cancer cells, differentiates neuronal cells, and increases the uptake of mQDs in zebrafish embryos. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/545347v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@f521a4org.highwire.dtl.DTLVardef@173a8f0org.highwire.dtl.DTLVardef@585271org.highwire.dtl.DTLVardef@8c959d_HPS_FORMAT_FIGEXP M_FIG C_FIG

This study had a two-fold objective: To utilize collagen hydrolysate for synthesizing a nanoscale Hydroxyapatite (HA) coating that would act as a superior osteoblast adhesion/proliferation agent compared to collagen-derived HA (C/HA) and to comprehend the significant role played by structural constraints on HA nucleation. Collagen was extracted from pacu skin with a high yield of 65.3% (w/w of tissue). It was digested by collagenase and the hydrolysate (CH) was purified with a high yield of 0.68g/g of collagen. The CH peptides had a mass of 6kDa, a predominant PP-II conformation and formed self-assembling hierarchical structures at physiological pH with dimensions of 842.2{+/-}229nm. The HA synthesized on CH (CH/HA) displayed higher yield when compared to C/HA. Structural analysis of CH/HA revealed that the PP-II peptides coiled to form mimic-helical moieties with reduced intermolecular packing distance of 0.9nm. The mimic helices cross-linked to form a vast quasi-fibrillar network that was comparatively smaller than collagen fibrils but exhibited enhanced stability and greater dynamicity. CH/HA displayed intense calcium-carboxyl interactions, sharper diffraction planes, smaller size of 48{+/-}6.2nm and a Ca/P ratio closer to 1.69 when compared to C/HA along with displaying serrated edge blooming crystals. Because of the small size, the CH/HA nanocrystals displayed significantly better osteoblast adhesion than C/HA and reduced the doubling time of cells. Overall, the results indicated that CH based nanocomposites displayed suitable morphological characteristics and cellular response for potential application as implant and bone graft coating material. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/431097v1_ufig1.gif" ALT="Figure 1"> View larger version (57K): org.highwire.dtl.DTLVardef@1b020c2org.highwire.dtl.DTLVardef@36a899org.highwire.dtl.DTLVardef@77106aorg.highwire.dtl.DTLVardef@d6b801_HPS_FORMAT_FIGEXP M_FIG C_FIG

The rapid emergence of drug-resistant bacteria and fungi poses a threat for healthcare worldwide. The development of novel effective small molecule therapeutic strategies in this space has remained challenging. An orthogonal approach, therefore, is to explore biomaterials with physical modes of action which have the potential to generate antimicrobial activity and in some cases even prevent antimicrobial resistance. Here, to this effect, we describe an approach for forming silk-based films that contain embedded selenium nanoparticles. We show that these materials exhibit both antibacterial and antifungal properties while crucially also remaining highly biocompatible and non-cytotoxic towards mammalian cells. By incorporating the nanoparticles into silk films, the protein scaffold acts in a two-fold manner; it protects the mammalian cells from the cytotoxic effects of the bare nanoparticles, while also providing a template for bacterial and fungal eradication. A range of hybrid inorganic/organic films were produced and an optimum concentration was found, which allowed for both high bacterial and fungal death while also exhibiting low mammalian cell cytotoxicity. Such films can thus pave the way for next generation antimicrobial materials for applications such as wound healing and as agents against topical infections, with the added benefit that bacteria and fungi are unlikely to develop antimicrobial resistance to these hybrid materials.

We successfully harnessed the potential of Artemisia pallens extracts for the eco-friendly biosynthesis of silver, gold, and silver-gold bimetallic nanoparticles, employing aqueous silver nitrate and chloroauric acid solutions. This innovative approach departs from traditional methods, often involving toxic chemical agents like hydrazine hydrate and sodium borohydride. In the quest for greener protocols, the biological route emerges as a non-toxic, straight-forward, and environmentally sound alternative, opening new avenues for translational research. This article discusses the production of silver, gold, and silver-gold nanoparticles using different species of Artemisia plants. Nanoparticle characterization was carried out using UV-visible spectrophotometry, TEM, XRD, and FTIR techniques. Microwave-assisted synthesis resulted in well-dispersed nanoparticles. In the case of silver nanoparticles, a spherical shape with a size of 6 nm was achieved using the microwave radiation-assisted method, while a size of 20 nm was obtained with UV-assisted synthesis. Gold nanoparticles exhibited diverse shapes, including spherical, triangular, prisms, trapezoids, and hexagonal, with a predominant size of 10 nm. The size range for gold nanoparticles varied from 10 nm to 400 nm.

We report the controlled release of an antimicrobial peptide using enzyme-activatable prodrugs to treat and detect Candida albicans and Porphyromonas gingivalis. Our motivation lies in the prevalence of these microorganisms in the subgingival area where the frequency of fungal colonization increases with periodontal disease. This work is based on an antimicrobial peptide that is both therapeutic and induces a color change in a nanoparticle reporter. This antimicrobial peptide was then built into a zwitterionic prodrug that quenches its activity until activation by a protease inherent to these pathogens of interest: SAP9 or RgpB for C. albicans and P. gingivalis, respectively. We first confirmed that the intact zwitterionic prodrug has negligible toxicity to fungal, bacterial, and mammalian cells absent a protease trigger. Next, the therapeutic impact was assessed via disk diffusion and viability assays and showed a minimum inhibitory concentration of 3.1 - 16 {micro}g/mL, which is comparable to the antimicrobial peptide alone (absent integration into prodrug). Finally, the zwitterionic design was exploited for colorimetric detection of C. albicans and P. gingivalis proteases. When the prodrugs were cleaved, the plasmonic nanoparticles aggregated causing a color change with a limit of detection of 10 nM with gold nanoparticles and 3 nM with silver nanoparticles. This approach has value as a convenient and selective protease sensing and protease-induced treatment mechanism based on bioinspired antimicrobial peptides. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=78 SRC="FIGDIR/small/568833v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@1e9cf5corg.highwire.dtl.DTLVardef@12cb36forg.highwire.dtl.DTLVardef@1b862f7org.highwire.dtl.DTLVardef@697946_HPS_FORMAT_FIGEXP M_FIG C_FIG

Photo-crosslinkable hydrogels are widely employed in biofabrication and tissue engineering as they provide spatiotemporal control over gelation. Most conventional photo-curing hydrogel systems rely upon small-molecule photoinitiators which, upon activation by (ultra)violet irradiation, generate free radicals to initiate polymerization. Such an approach can induce oxidative stress and DNA damage, significantly limiting their use in sensitive biological applications. Here, we present a photoinitiator-free, gelatin-based hydrogel system functionalized with acrylamidylpyrene groups (Gel-Pyr), which undergoes photocrosslinking via a visible-light-induced [2+2] cycloaddition reaction. Gel-Pyr exhibits rapid gelation kinetics, tuneable mechanical properties, facile temporal control over photocrosslinking, and long-term structural stability (>30 days) in cell culture conditions. Rheological analyses reveal pronounced shear-thinning behaviour at room temperature, enabling extrusion-based 3D bioprinting of multilayered constructs with high structural fidelity. Fine strand resolution (<400 {micro}m) is achieved in bioprinted crosshatch structures, enabling sufficient nutrient diffusion for cell support. Encapsulation of human mesenchymal stem cells (hMSCs) within both bulk and printed constructs maintains >80% viability over 7 days, demonstrating robust cytocompatibility. By eliminating UV exposure and free radicals, this visible-light-responsive hydrogel platform offers a facile and cytoprotective alternative to other hydrogel systems. Table of ContentA visible light-crosslinkable, initiator-free gelatin-based hydrogel (Gel-Pyr) is developed using acrylamidylpyrene functionalization. This radical-free system enables rapid crosslinking under cytocompatible reaction conditions and offers excellent printability, tuneable mechanics, and long-term stability. Gel-Pyr supports high cell viability and precision bioprinting, positioning it as a promising platform for tissue engineering and in vitro biofabrication. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=181 SRC="FIGDIR/small/691472v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@168fbd5org.highwire.dtl.DTLVardef@16d7e7forg.highwire.dtl.DTLVardef@18beea3org.highwire.dtl.DTLVardef@1e02cd9_HPS_FORMAT_FIGEXP M_FIG C_FIG

"Green nanotechnologies have emerged as environmentally friendly alternatives against microbial multidrug-resistant biofilms. In this study, bactericidal "green" nanolayers (NL) were developed on Ti surfaces using two isomeric phytocompounds, carvacrol (Carv-Ti-NL) and thymol (TOH-Ti-NL). These NLs were fabricated using a one-step immersion treatment method based on a simple and spontaneous self-assembly process. Both NLs revealed strong antimicrobial activity, displaying anti-biofilm and biocidal effects. Notably, TOH-Ti-NL exhibited superior osteogenic performance compared to Carv-Ti-NL, as evidenced by enhanced pre-osteoblast cell attachment and growth, and the production of ALP, collagen type I and Ca2+ deposition. In contrast, fibroblastic cells exhibited reduced attachment on TOH-Ti-NL and enhanced proliferation on Carv-Ti-NL. Considering the biological differential effects, the physicochemical properties of these conformational isomers NLs were studied to elucidate potential differences that could impact on cell response. Although the ATR-FTIR spectra of the NLs were similar and indicated the spontaneous oxidation of Carv and TOH leading to ketonic structures, distinct contributions were observed after the electrooxidation of each NL. Slight differences in hydrophilicity were found for both nanostructures, but higher roughness was found for TOH-Ti-NL. Furthermore, the release curves of Carv and TOH from the NLs revealed distinct profiles over time. Overall, Carv and TOH formed self-assembled layers on Ti able to eradicate Staphylococcus aureus biofilms. Their different physical and chemical characteristics induced distinct responses from eukaryotic cells attached to the NLs. Given these characteristics one might envisage the use of either Carv-Ti-NL or TOH-Ti-NL in order to fine-tune specific chemical physical properties of Ti-based implants. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=132 SRC="FIGDIR/small/610464v1_ufig1.gif" ALT="Figure 1"> View larger version (66K): org.highwire.dtl.DTLVardef@1c288f5org.highwire.dtl.DTLVardef@adc72corg.highwire.dtl.DTLVardef@ef2763org.highwire.dtl.DTLVardef@102d823_HPS_FORMAT_FIGEXP M_FIG C_FIG

Red-emitting carbon nanoparticles (CNPs) were synthesized by the refluxed green synthesis method using ethanolic extract of neem leaves (Azadirachta indica). These nanoparticles were called as nQDs (neem quantum dots). The nQDs exhibited excellent photoluminescence properties with a maximum emission at 672nm, and the average size of nQDs was around 47nm. In the in-vitro study, Retinal Pigment epithelial (RPE1) cells and SUM159A cells showed enhanced cellular uptake. In RPE1 cells, the cellular uptake was higher than in SUM159A cells. In the biocompatibility assay, SUM159A cell viability declined with the increasing nQDs concentration. The results show that red-emissive CNPs can be synthesized from Azadirachta indica (neem) leaves using a simple method with a possible application in bioimaging and therapeutics. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=148 SRC="FIGDIR/small/582094v1_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@30da5aorg.highwire.dtl.DTLVardef@14f6fbcorg.highwire.dtl.DTLVardef@30e0f0org.highwire.dtl.DTLVardef@ffc962_HPS_FORMAT_FIGEXP M_FIG C_FIG

This study investigates the synthesis of pH-responsive, reversible nanocomposites comprising polystyrene sulfonate (PSS)-coated gold nanorods and poly(allylamine hydrochloride) (PAH)-coated gold nanorods, along with their optical properties. We observed a pH-dependent swelling/shrinking of the nanocomposites and a dramatic red-shift ([~] 60 nm) of the surface plasmon resonance (SPR) peaks as the pH changed from around 5.4 to 7.2 due to the increased side-by-side interactions of adjacent gold nanorods. These pH-responsive nanocomposites, with tunable SPR peaks, hold potential for use as contrast agents in optical molecular imaging. GRAPHICAL ABSTRACTpH-Sensitive Polymer-Coated Gold Nanorods for Reversible SPR Shifts and Applications in pH Sensing as Optical Materials. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=145 SRC="FIGDIR/small/646487v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@1bb05bforg.highwire.dtl.DTLVardef@1767c02org.highwire.dtl.DTLVardef@1c77356org.highwire.dtl.DTLVardef@1654647_HPS_FORMAT_FIGEXP M_FIG C_FIG

The biosynthesis of silver nanoparticles has recently emerged as a promising approach in nanomedicine, particularly for targeted therapeutic applications. Green synthesized (plant-based) nanoparticles have been shown to offer enhanced reduction efficiency, greater bioavailability, and improved stability compared to synthetic nanoparticles. Here, we report the green synthesis of silver nanoparticles (AgNPs) using Magnolia alba leaf extract. The formation of these Magnolia-derived silver nanoparticles (MAgNPs) was verified through UV-Vis spectroscopy and further characterized by scanning electron microscopy (SEM) which showed that the MAgNPs have a mean diameter of 40 nm and a spherical morphology. The antibacterial efficacy of MAgNPs, evaluated by the well diffusion method, showed significant activity against E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterococcus faecalis, and strains of methicillin-resistant and -sensitive Staphylococcus aureus. Disc diffusion and plaque assays demonstrated notable antifungal activity against Candida albicans and antiviral activity against bacteriophage T7. In vitro studies with HCT-116 human colon cancer cells, MAgNPs exhibited significant bi-phasic inhibition of cancer cell growth. These effects were greater than that of the magnolia leaf extracts alone, confirming the green synthesized nanoparticles bioactive efficacy. These findings suggest that MAgNPs possess significant antimicrobial and anticancer activities, indicating their potential as therapeutic agents for certain infections and cancers. Antioxidant assays indicated that MAgNPs exhibit greater antioxidant activity than magnolia leaf extract alone. Results suggest that MAgNPs may have promise as antioxidants for treating free radical-induced disorders. Additionally, MAgNPs showed efficient photocatalytic degradation of the azo bond in methyl orange within 30 minutes, suggesting they may provide a sustainable approach to certain types of environmental pollution. To our knowledge, this is the first report of the biosynthesis of silver nanoparticles using Magnolia alba and examination of their antioxidant and photocatalytic properties, their killing and inhibitory effects on various bacteria, fungi, bacteriophages, and colon cancer.

We present a new class of nitrogen-doped yellow fluorescent carbon dots, synthesized using a one-step hydrothermal method. These bright fluorescent nanoparticles have excitation and emission spectra near the red region of the visible light spectrum that are quite useful for bioimaging applications. Using organic molecules like ortho- phenylenediamine (OPDA), L-ascorbic acid and urea, yellow fluorescent carbon dots (CDs) were synthesized. We obtained a scalable number of CDs having an average size of 3 nm. The CDs show significant emission spectra in the yellow fluorescence region ({lambda}em= 557 nm). The CDs show remarkable stability in their fluorescence in different pH conditions, ionic stability, photostability as well as thermal stability. These CDs are efficiently uptaken by mammalian cells through clathrin-mediated pathway. Apart from in vitro studies we have also used zebrafish larvae as a 3D in vivo model, and showed that CDs were uptaken efficiently by larvae showing maximum accumulation and fluorescence in the yolk sac region and the notochord region. The CDs also offer enhancement in cell proliferation, hence showing the application in wound healing. The fluorescence of CDs is quite robust and is not affected by most external stimuli, hence can be explored as a promising bioimaging tool for targeted bioimaging and biomedical applications.

As the world recovers from the lockdown imposed by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic, returning to shared indoor spaces is considered a formidable risk. It is now clear that transmission of SARS-CoV-2 is driven by respiratory microdroplets expelled by infected persons, which can become suspended in the air. Several layering technologies are being explored to mitigate indoor transmission in the hopes of re-opening business, schools and transportation systems. Here we coupled the water adsorptive and photocatalytic capacity of novel Metal Organic Frameworks (MOFs) to demonstrate the capture and inactivation of SARS-CoV-2. Discussion is given on the methods of analysis and the differences between the photocatalytic activity of several MOFs, and the difference between MOF induced photocatalysis and ultra violet photolysis of SARS-CoV-2. Our results are intended to provide support to industry looking for alternative methods secure indoor spaces.

1Self-assembled monolayers (SAMs) have been widely utilized as a way of tailoring surface chemistry through the adsorption of organic molecules to different materials. SAMs are easy to prepare and offer a wide variety of organic molecules that afford additional or improved properties to the coated material. Spatial control of SAM placement has been achieved over many length-scales, even at the nanoscale. However, nanopatterned SAMs are usually prepared through serial processes utilizing atomic scanning probes or soft-lithography utilizing elastomeric masters. These techniques are expensive or not repeatable. Here we present the use of nanospheres for the creation of nanopatterned Au:Cu films which spatially control the grafting of a thermoresponsive SAM made from poly(N-isopropyl acrylamide) (PNIPAM). Chemical characterization validates the presence of PNIPAM and environmental atomic force microscopy showed its response to temperature which was evidenced by a change in stiffness. Our approach represents an affordable large area methodology for repeatable spatial control of SAMs at the nanoscale.

Copper is involved in the biosynthesis of collagen, however soluble copper salts dissipate quickly and copper nanoparticles are cytotoxic. Here we added a novel copper-containing nanomaterial (CuHARS) to assess human chondrocyte function in the presence of copper. Human dermal fibroblasts (HDFs) were also treated as a control. Chondrocyte response to CuHARS was assessed by chronic nanomaterial treatment (30 {micro}g/ml) followed by digital microscopy and image analysis of cellular features compared to normal chondrocytes. Unexpectedly, chronic CuHARS treatment of human chondrocytes transformed cells over time to cells with extremely elongated and variegated processes and lower proliferation rates compared to normal chondrocytes. In these transformed cells, which we named 3G, shedding of fine processes was observed over time and collected supernatants demonstrated elevated collagen levels compared to normal cell culture media. In contrast to chondrocytes, HDFs treated with CuHARS showed attenuated changes in morphology, and notably retained a prominent ability for continued proliferation. These results demonstrate that a copper-containing biohybrid material (CuHARS) can stably transform human chondrocytes with highly altered morphology, lower proliferation rates, and altered membrane dynamics compared to normal chondrocytes. In contrast, human dermal fibroblasts demonstrated attenuated changes in morphology, and retained an enhanced ability for proliferation.

AbstractBiofilms are structured communities of microbial cells embedded in a self-produced matrix of extracellular polymeric substances. Biofilms are associated with many health issues in humans, including chronic wound infections and tooth decay. Current antimicrobials are often incapable of disrupting the polymeric biofilm matrix and reaching the bacteria within. Alternative approaches are needed. Here, we describe a unique structure of dextran coated gold in a gold cage nanoparticle that enables photoacoustic and photothermal properties for biofilm detection and treatment. Activation of these nanoparticles with a near infrared laser can selectively detect and kill biofilm bacteria with precise spatial control and in a short timeframe. We observe a strong biocidal effect against both Streptococcus mutans and Staphylococcus aureus biofilms in mouse models of oral plaque and wound infections respectively. These effects were over 100 times greater than that seen with chlorhexidine, a conventional antimicrobial agent. Moreover, this approach did not adversely affect surrounding tissues. We conclude that photothermal ablation using theranostic nanoparticles is a rapid, precise, and non-toxic method to detect and treat biofilm-associated infections.

Cancer remains one of the most critical global health challenges, with early detection being essential for effective treatment and improved survival rates. However, conventional diagnostic tools often fail to detect cancer at early stages due to limitations such as low sensitivity, high cost, and dependence on large tumour presence. Commercial dyes used for imaging are frequently hindered by poor water solubility, toxicity, instability, and high expense. In recent years, CDs have emerged as promising fluorescent probes due to their nanoscale size, tenable surface properties, strong fluorescence, and excellent biocompatibility. make them applicable to various biological applications such as bioimaging, drug delivery, and tissue engineering. In this study, CDs were synthesized using citric acid and ascorbic acid as carbon sources via a reflux method at 130 {degrees}C for 12 hours in a water-ethanol medium. The resulting CDs exhibited high water solubility, strong photostability, and low toxicity. Notably, they effectively distinguished cancerous cells from normal cells. And showing higher uptake in cancer cells due to increased membrane permeability and metabolic activity. Higher uptake means more accumulation within cells that leads to an increment in fluorescence intensity, based on the fluorescent intensity distinguishing the cancer cells and normal cells. These findings highlight the potential of CDs as cost-effective, biocompatible imaging agents for cancer diagnosis and cellular studies.

SU-8 polymer is an excellent platform for diverse applications due to its high aspect ratio of micro/nanostructures fabrication and exceptional optical, chemical, and biocompatible properties. Although SU-8 has been often investigated for a variety of biological applications, how its surface properties influence both the interaction of bacterial cells with the substrate and its colonization is poorly understood. In this work, we tailor SU-8 nanoscale surface properties to investigate single cell motility, adhesion and successive colonization of a phytopathogenic bacteria, Xylella fastidiosa. Different surface properties of SU-8 thin films have been prepared using photolithography processing and oxygen plasma treatment. We found a significant difference in bacterial cell behavior and subsequent colonization on SU-8 as surface property changes. A larger density of carboxyl groups in hydrophilic plasma-treated SU-8 surfaces promotes faster cell motility in the earlier stage of the growth. The hydrophobic nature of pristine SU-8 surfaces has no trackable bacterial motility with 5 to 10 times more single cells adhered to surface than its plasma-treated counterpart. In fact, plasma-treated SU-8 samples suppressed bacterial adhesion, with surfaces showing less than 5% coverage. These results not only showcase that SU-8 surface properties can impact the bacterial behavior in a spatiotemporal manner, but also provide insights on the prominent ability of pathogens to evolve and adapt to different surface properties.