ACS Applied Bio Materials

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.

In this paper, we report for the first time, the synthesis of a semiconducting biofilm. Photosynthetic bacterial biofilm has been used to weave together MoS2 nanosheets into an adherent film grown on interdigitated electrodes. Liquid-phase exfoliation of bulk MoS2 powder was used to obtain MoS2 nanosheets. A synchronous-fluorescence scan revealed the presence of two emission maxima at 682nm and 715nm for the MoS2 suspension. Such maxima with bandgap energy 1.82 and 1.73 eV corresponded to the single and double layer of MoS2. The presence of such single and multi-layered structures was confirmed by Raman spectroscopy, FTIR studies, and electron microscopy. The current-voltage (I-V) studies of such a bio-nano hybrid revealed the emergence of the gated nature of the current flow. This Schottky diode like behavior, reported earlier for Graphene-biofilm junctions, is also observed in this case. Gating voltage depended on the composition of the biofilm. The semiconductor biofilms, when studied using electrochemical impedance spectroscopy, revealed characteristic Nyquist and Bode plots, suggesting special circuit-equivalence for each film. While Mos2 was marked with stability with respect to variations in RMS voltage and bias voltage, the graphene biofilm was unique by the absence of any Warburg element.

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.

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.

Microbial-mediated drug delivery systems have the potential to significantly enhance the efficacy of nanomedicine for cancer therapy through improved specificity and interstitial transport. The Nanoscale Bacteria-Enabled Autonomous Drug Delivery System (NanoBEADS) is a bacteria-based bio-hybrid drug delivery system designed to carry nanotherapeutics cargo deep into poorly vascularized cancerous tissue. The effect of bacteria-nanoparticle conjugation method and NanoBEADS assembly parameters (i.e., mixing method, volume, and duration) was investigated to maximize particle attachment density. The nanoparticle attachment capacity, viability, growth rate and motility of the original NanoBEADS and an antibody-free variant NanoBEADS were characterized and compared. It is found that the assembly parameters affect the attachment outcome and the binding mechanism impacts the attachment number, the growth rate and motility of NanoBEADS. The NanoBEADS platform provides an opportunity to load nanoparticles with different materials and sizes for applications beyond cancer therapy, such as imaging agents for high-resolution medical imaging.

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

There has been growing interest in optical coherence tomography (OCT) imaging at a wavelength of 1060 nm. However, potential contrast agents for OCT imaging at this specific wavelength has not been thoroughly investigated. In this study, we present the synthesis and optical characterization of gold nanocages with a small edge length ([~]65 nm) and a surface plasmon resonance peak around 1060 nm. These nanocages represent a class of potential contrast agents for OCT at 1060 nm. OCT imaging experiments were conducted on phantoms and in vivo mouse tissues using a 1060-nm swept-source OCT system, demonstrating significant enhancement in imaging contrast due to the presence of the gold nanocages. GRAPHICAL ABSTRACTGold nanocages with a long SPR peak wavelength as OCT imaging contrast agents at 1060 nm O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/642209v1_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@179a727org.highwire.dtl.DTLVardef@1cd1e4eorg.highwire.dtl.DTLVardef@180ce47org.highwire.dtl.DTLVardef@166a779_HPS_FORMAT_FIGEXP M_FIG C_FIG

Carbon-based fluorescent quantum dots are an emerging class of nanoparticles for targeted bioimaging and biomedical applications. We present a facile microwave-assisted approach for synthesizing carbon nanoparticles with bright red fluorescence using ethanolic extracts of Spinacia oleracea leaves, with a quantum yield of 94.67%. These nanoparticles, called CNPs, ranging from 15-50 nm, demonstrated fluorescence emission in the near-infrared (NIR) region between 650 and 700 nm, independent of excitation wavelength. Upon excitation at a wavelength of 410 nm, they exhibit an emission maxima peak at 672 nm. The significant uptake of CNPs in mammalian cells and zebrafish larvae highlights their potential as bioimaging agents in diverse biomedical applications in vivo. Further, these quantum dots enhance cellular proliferation and migration as observed by wound healing assay in mammalian cells, indicating their possible application in tissue engineering and regenerative medicine. These findings suggest that biosynthesized carbon nanoparticles possess significant potential for biomedical activities, which can serve as a robust benchmark for researchers towards promoting sustainability.

Respiratory infections pose a serious threat worldwide, and many new antiviral agents and coatings have been developed to reduce the overall risk of viral infection. Here, we evaluate the methodology used to test these antiviral coatings and developed a novel system that is more similar to "real-world" conditions. Contact infection is largely mediated via contact with saliva containing the active virus released as droplets by coughing or sneezing, with these droplets adhering to objects and surfaces and subsequently entering the human body via indirect contact with the mucous membranes. Here, we evaluated the antiviral effect of a known antiviral coating agent using an artificial saliva based system, where artificial saliva containing phages were sprayed onto the antiviral coating under various conditions associated with viral replication and infectious spread. We used a commercially available antiviral coating in this evaluation, and M13 bacteriophages as model viruses. This method enables simple biomimetic evaluations of any products antiviral effects.

The morphological dynamics of microbial cell proliferation on an antimicrobial surface at an early growth stage was studied with Escherichia coli on the surface of a gel supplied with nanostructured AgNbO3 antimicrobial particles. We demonstrated an inhibitory surface concentration, analogous to minimum inhibitory concentration, beyond which the growth of colonies and formation of biofilm are inhibited. In contrast, at lower concentrations, colonies circumvent the antimicrobial activity of the particles and grow with a short lag time of a few hours. The applicability of these findings, in terms of estimating inhibitory surface concentration, was tested in the case of antimicrobial polymethyl methacrylate (PMMA) bone cement.

Gene therapy outperforms chemotherapy in limiting the harm to human body. A major impediment to the progress of gene therapy is a lack of proper carriers. Chitosan, derived from shellfish, is a desirable candidate for nucleic acid delivery because of its outstanding biodegradability and biocompatibility. However, previous works show that chitosan has poor cell membrane permeability. In this study, we synthesize a complex delivery system for gene therapy by compounding chitosan with L-arginine, and test the encapsulation, uptake, and cancer cell treatment power. Encapsulation efficiency of the chitosan/L-arginine complex (CA) can reach more than 90% in weight. Flow cytometry reveal that siRNA delivered by the complex can be taken in by cells 10 times better than free siRNA and 2 times better than chitosan alone. Confocal imaging confirmed the high cellular uptake, and siRNA tests in HeLa cells indicate the successful silencing of the target gene (RRM2). The complex serves as a gene delivery system that is capable of loading and delivering a variety of genetic materials in which the specific nucleic acid molecule to be delivered could be altered at will.

The remarkable biocompatibility and supreme physical properties of nanostructured TiO2 have promised itself a strong future for biomedical applications. The present study reported a theoretical study on the adsorption of rutile TiO2 (110) nanosheet for DNA nucleobases using first-principles calculations. The calculations of the binding energy and work function demonstrate that the TiO2 nanosheet has remarkable adsorption strength to the DNA nucleobases, being more than 20 times larger than that of graphene and its derivatives. Further electronic band structure and density of state calculations elucidate the interaction mechanisms, which originate from dramatically reduced energy levels and strong hybridization of the 2p orbital of C, N and/or O with 3d orbital of Ti atoms near the Fermi level. The study directs a promising material at applications in DNA sensors and sequencers.

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.

Tetrahedral DNA nanostructures (TDNs) are promising nanocarriers due to their structural precision, biocompatibility, and efficient cellular uptake. However, their stability under physiological conditions remains a key challenge. In this study, TDNs were synthesized via a one-pot thermal annealing method and characterized using native PAGE, dynamic light scattering (DLS), and zeta potential analysis, confirming uniform size ([~]13 nm) and negative surface charge. Their stability was systematically evaluated across different biological media (DMEM complete, serum-free DMEM, and E3), temperatures (4 {degrees}C, 25 {degrees}C, and 37 {degrees}C), and pH conditions (4.0, 7.0, and 8.5) over 24 h. Results revealed rapid degradation in serum-containing medium, increased instability at higher temperatures, and reduced stability under acidic conditions, while serum-free, lower-temperature, and neutral to mildly basic environments enhanced structural integrity. These findings highlight the strong environmental dependence of TDN stability and provide insights for optimizing their design for biomedical applications.

Small sized, carbon-based organic nanoparticles have recently gained attention due their advantage of biocompatibility, photostability and biological non-toxicity as compared to their inorganic counterparts. Herein, a new class of small (5-8 nm), green emitting fluorescent carbon quantum dots (GCQDs) were synthesized using organic substrates like citric acid and ascorbic acid in aqueous solvent containing water and ethanol. The very small size and bright green photoluminescence prompted their use for both in vitro and in vivo bioimaging. GCQDs were uptaken via clathrin mediated pathways in mouse kidney and liver primary cells. Similarly, they showed active uptake and distribution in the zebrafish embryo model system. The optical tunability and surface modification properties of these GCQDs provide a platform to be explored for them to emerge as a new class of targeted bioimaging entities, as well as tools for biomedical applications.

We report a simple, cost-effective, microwave-assisted green synthesis route of red-emitting fluorescence carbon nanoparticles (CNPs) using Psidium guajava (Guava leaves). The synthesis of CNPs is a simple, affordable, and rapid method of producing carbon nanoparticles. The CNPs were characterized by various spectroscopic and microscopic techniques. Atomic force microscopy studies showed that the average size of CNPs is approximately 50 nm. The CNPs exhibited excellent photoluminescence properties with a maximum emission at 677 nm, making them suitable for bioimaging applications. The Ionic, photostability, and thermal stability of CNPs were also checked to understand their robustness. Retinal pigment epithelium (RPE) cells were exposed to these nanoparticles and showed very efficient uptake, some fraction of it also getting targeted to the nucleus, indicating that CNPs are non-toxic and biocompatible for future biological experiments. The results indicate that guava leaves can be a promising source for the synthesis of red emissive CNPs through the very simple method of synthesis and with bioimaging applications.

The aggregation state and endosomal trapping of engineered nanocarriers once internalized into cells remain poorly characterized. Here, we visualized the membrane penetrating dynamics of semiconductor quantum dots (QDs) into the cytosol of T cells on a single-cell and single-nanoparticle basis. We water solubilized CdSe/CdZnS QDs with polymer encapsulants functionalized with a cell-penetrating peptide composed of an Asp-Ser-Ser (DSS) repeat sequence. T cells tolerated the 24-h incubation with QDs at concentrations of 5 nM or lower. Single-particle imaging demonstrated that the number of internalized nanoparticles was dependent upon the concentration of the probes for both control (peptide-free) and DSS-QDs. DSS-QDs were mostly distributed as monomers, whereas the control QDs were aggregated into clusters. Single-particle tracking using total internal reflection and highly inclined illumination showed that DSS-QDs were stationary near the activating surface and mobile within the cytosol of the T cell. A correlation exhibited between the mobility and aggregation state of individual QD clusters, with monomeric DSS-QDs showing the highest mobility. In addition, monomeric DSS-QDs displayed much faster diffusion than the endosomes. A small-molecule endosome marker confirmed the absence of colocalization between endosomes and DSS-QDs, indicating their endosomal escape. The ability to deliver and track individual QDs in the cytosol of live T cells creates inroads for the optimization of drug delivery and gene therapy through the use of nanoparticles.

Triplet-triplet annihilation upconversion (TTA-UC) nanoparticles (NPs) have emerged as imaging probes and therapeutic probes in recent years due to their excellent optical properties. In contrast to lanthanide ions-doped inorganic materials, highly efficient TTA-UC can be generated by low excitation power density, which makes it suitable for clinical applications. In the present study, we used biodegradable poly(lactic-co-glycolic acid) (PLGA)-NPs as delivery vehicle for TTA-UC based on the heavy metal porphyrin Platinum(II) octaethylporphyrin (PtOEP) and the polycyclic aromatic hydrocarbon 9,10-diphenylanthracene (DPA) as photosensitizer/emitter pair. TTA-UC-PLGA-NPs were successfully synthesized according to an oil-in-water emulsion and solvent evaporation method. After physicochemical characterization, UC-efficacy of TTA-UC-PLGA-NPs was assessed in vitro and ex vivo. TTA-UC could be detected in the tumor area 96 hours after in vivo administration of TTA-UC-PLGA-NPs, confirming the integrity and suitability of PLGA-NPs as TTA-UC in vivo delivery system. Thus, this study provides proof-of-concept that the advantageous properties of PLGA can be combined with the unique optical properties of TTA-UC for the development of advanced nanocarriers for simultaneous in vivo molecular imaging and drug delivery.

The excised animal cornea is the gold standard for testing and evaluating drug permeability through a cornea. However, it has a concise shelf life and encounters ethical concerns. Also, ex-vivo models, which are incomplete replicas of the human cornea, may provide faulty results in the pre-clinical studies. To circumvent these problems, we have proposed an in-vitro biomimetic lipid-polymer composite membrane (BLCM) model as an artificial cornea to study drug permeability. We designed and fabricated a free-standing, electro-spun polystyrene (PS) nanofibrous membrane and impregnated its pores with phosphatidylcholine (PC). SEM, FTIR, and goniometer characterized the BLCM. Permeation data of the drug ganciclovir through the BLCM model in a Franz-diffusion cell corroborates with the excised goat corneal system. Also, owing to the simple and scalable fabrication method, BLCM can be used as an alternative to animal models for initial drug permeability screening and studies and accelerate drug development.

The extraordinary self-assembling nature of DNA nanostructures and high functionality enables the formulation of DNA nanostructures with multiple chemical and biological molecules. How the whole organisms in native as well as modified; and how stable they are inside take up exactly these modified DNA nanostructures the organisms still remains to be explored. Here we report the fabrication and evaluation of a new conjugate of a cationic lipid, N-[one-(two, 3-dioleyloxy) propyl]-N, N, N-trimethylammonium chloride (DOTMA) and DNA tetrahedron nanostructure (TdN) for the enhanced uptake, stability, bioimaging, and biotherapeutics in cells and zebrafish (Danio rerio) eleuthero embryos as a model organism. We summarise the enhanced uptake potential of TdN-DOTMA conjugate for futuristic biomedical applications such as drug delivery, bioimaging, biosensing, and therapeutics.