Turning food waste into value-added carbon dots for sustainable food packaging application: A review

Carbon dots (CDs) are a recent addition to the nanocarbon family, encompassing both crystalline and amorphous phases. They have sparked significant research interest due to their unique electrical and optical properties, remarkable biocompatibility, outstanding mechanical characteristics, customizable surface chemistry, and negligible cytotoxicity. Their current applications are mainly limited to flexible photonic and biomedical devices, but they have also garnered attention for their potential use in intelligent packaging. The conversion of food waste into CDs further contributes to the concept of the circular economy. It provides a comprehensive overview of emerging green technologies, energy-saving reactions, and cost-effective starting materials involved in the synthesis of CDs. It also highlights the unique properties of biomass-derived CDs, focusing on their structural performance, cellular toxicity, and functional characteristics. The application of CDs in the food industry, including food packaging, is summarized in a concise manner. This paper sheds light on the current challenges and prospects of utilizing CDs in the packaging industry. It aims to provide researchers with a roadmap to tailor the properties of CDs to suit specific applications in the food industry, particularly in food packaging.

Comparison of Wavelength-Dependent Penetration Depth of 532 nm and 660 nm Lasers in Different Tissue Types

Introduction: The depth of laser light penetration into tissue is a critical factor in determining the effectiveness of photodynamic therapy (PDT). However, the optimal laser light penetration depth necessary for achieving maximum therapeutic outcomes in PDT remains unclear. This study aimed to assess the effectiveness of laser light penetration depth at two specific wavelengths, 532 nm and 660 mm. Methods: Chicken and beef of different thicknesses (1, 3, 5, 10, and 20 mm±0.2 mm) were used as in vitro tissue models. The samples were subjected to irradiation by a low-level laser diode of 532 and 660 nm in continuous mode for 10 minutes. with power densities of 167 and 142 J/cm2, respectively. Laser light transmission through the tissue was measured using a power meter. Results: For beef samples, the 660 nm wavelength achieved a maximum transmission intensity of 30.7% at 1 cm thickness, while the 532 nm laser had a transmission intensity of 6.5%. Similarly, in chicken breast samples, the maximum transmission occurred at 1 cm thickness with 68.1% for the 660 nm wavelength and 18.2% for the 532 nm laser. Conclusion: Results consistently demonstrated a significant correlation (P<0.05) between tissue thickness and laser light penetration. Thicker tissues exhibited faster declines in light transmission intensity compared to thinner tissues within 10 minutes. These findings highlight the importance of further research to enhance light delivery in thicker tissues and improve the efficacy of PDT in various medical conditions.

Comparative Analysis of Stable Gold Nanoparticles Synthesized Using Sonochemical and Reduction Methods for Antibacterial Activity

The increasing bacterial resistance and negative impacts of the present antibacterial agents have led to the search for novel antibacterial agents. This study focuses on the influence of synthetic methods on the aggregation stability and antibacterial activity of gold nanoparticles (NPs) prepared by using sodium citrate as a reducing and capping agent against Staphylococcus aureus (S. aureus). Gold NPs were synthesized using a simple and rapid sonochemical method and compared to gold NPs synthesized using a reduction method. The physicochemical features of gold NPs were characterized using UV-vis, XRD, TEM, and zeta potential, and the TEM results showed that the sonochemical method produced monodispersed spherical gold NPs with an average diameter of 18.5 nm, while the reduction method produced NPs with an average diameter of around 20 nm. The sonochemical method produced gold NPs with excellent stability (-48 mV) compared to the reduction method (-21 mV). The gold NPs with high stability also exhibited strong antibacterial activity against S. aureus present in water, indicating their potential use in water purification processes to limit bacterial growth. The outcomes of this research are expected to significantly contribute to the creation of new drugs by paving the way for the development of novel strategies to combat pathogens using highly stable gold nanoparticles. These gold NPs, produced via the sonochemical method, have the potential to be employed as beneficial nanocompounds in the medical industry.

Optimization of ultrasonic-assisted approach for synthesizing a highly stable biocompatible bismuth-coated iron oxide nanoparticles using a face-centered central composite design

The incorporation of additional functional groups such as bismuth nanoparticles (Bi NPs) into magnetite nanoparticles (Fe3O4 NPs) is critical for their properties modification, stabilization, and multi-functionalization in biomedical applications. In this work, ultrasound has rapidly modified iron oxide (Fe3O4) NPs via incorporating their surface through coating with Bi NPs, creating unique Fe3O4@Bi composite NPs. The Fe3O4@Bi nanocomposites were synthesized and statistically optimized using an ultrasonic probe and response surface methodology (RSM). A face-centered central composite design (FCCD) investigated the effect of preparation settings on the stability, size, and size distribution of the nanocomposite. Based on the numerical desirability function, the optimized preparation parameters that influenced the responses were determined to be 40 ml, 5 ml, and 12 min for Bi concentration, sodium borohydride (SBH) concentration, and sonication time, respectively. It was found that the sonication time was the most influential factor in determining the responses. The predicted values for the zeta potential, hydrodynamic size, and polydispersity index (PDI) at the highest desirability solution (100%) were -45 mV, 122 nm, and 0.257, while their experimental values at the optimal preparation conditions were -47.1 mV, 125 nm, and 0.281, respectively. Dynamic light scattering (DLS) result shows that the ultrasound efficiently stabilized and functionalized Fe3O4NPs following modification to Fe3O4@Bi NPs, improved the zeta potential value from -33.5 to -47.1 mV, but increased the hydrodynamic size from 98 to 125 nm. Energy dispersive spectroscopy (EDX) validated the elemental compositions and Fourier transform infrared spectroscopy (FTIR) confirmed the presence of Sumac (Rhus coriaria) compounds in the composition of the nanocomposites. The stability and biocompatibility of Fe3O4@Bi NPs were improved by using the extract solution of the Sumacedible plant. Other physicochemical results revealed that Fe3O4NPs and Fe3O4@Bi NPs were crystalline, semi-spherical, and monodisperse with average particle sizes of 11.7 nm and 19.5 nm, while their saturation magnetization (Ms) values were found to be 132.33 emu/g and 92.192 emu/g, respectively. In vitro cytotoxicity of Fe3O4@Bi NPs on the HEK-293 cells was dose- and time-dependent. Based on our findings, the sonochemical approach efficiently produced (and RSM accurately optimized) an extremely stable, homogeneous, and biocompatible Fe3O4@Bi NPs with multifunctional potential for various biomedical applications.

Monte Carlo simulation of gold nanoparticles for X-ray enhancement application

BACKGROUND

Gold nanoparticles (Au NPs) are regarded as potential agents that enhance the radiosensitivity of tumor cells for theranostic applications. To elucidate the biological mechanisms of radiation dose enhancement effects of Au NPs as well as DNA damage attributable to the inclusion of Au NPs, Monte Carlo (MC) simulations have been deployed in a number of studies.

SCOPE OF REVIEW

This review paper concisely collates and reviews the information reported in the simulation research in terms of MC simulation of radiosensitization and dose enhancement effects caused by the inclusion of Au NPs in tumor cells, simulation mechanisms, benefits and limitations.

MAJOR CONCLUSIONS

In this review, we first explore the recent advances in MC simulation on Au NPs radiosensitization. The MC methods, physical dose enhancement and enhanced chemical and biological effects is discussed, followed by some results regarding the prediction of dose enhancement. We then review Multi-scale MC simulations of Au NP-induced DNA damages for X-ray irradiation. Moreover, we explain and look at Multi-scale MC simulations of Au NP-induced DNA damages for X-ray irradiation.

GENERAL SIGNIFICANCE

Using advanced chemical module-implemented MC simulations, there is a need to assess the radiation-induced chemical radicals that contribute to the dose-enhancing and biological effects of multiple Au NPs.

Recent advances in extraction, modification, and application of chitosan in packaging industry

Current environmental concerns fostered a strong interest in extracting polymers from renewable feedstocks. Chitosan, a second most abundant polysaccharide after cellulose, may prove to be a promising green material owing to its renewability, inherent biodegradablity, natural availability, non-toxicity, and ease of modification. This review is intended to comprehensively overview the recent developments on the isolation of chitosan from chitin, its modification and applications as a reinforcing candidate for food packaging materials, emphasizing the scientific underpinnings arising from its physicochemical properties, antimicrobial, antioxidant, and antifungal activities. We review various chitosan-reinforced composites reported in the literature and comprehensively present intriguing mechanical and other functional properties. We highlight the contribution of these mechanically robust and responsive materials to extend the shelf-life and maintain the qualities of a wide range of food commodities. Finally, we assess critical challenges and highlight future opportunities towards understanding the versatile applications of chitosan nanocomposites.

Upconversion lanthanide nanomaterials: basics introduction, synthesis approaches, mechanism and application in photodetector and photovoltaic devices

Upconversion (UC) of lanthanide-doped nanostructure has the unique ability to convert low energy infrared (IR) light to high energy photons, which has significant potential for energy conversion applications. This review concisely discusses the basic concepts and fundamental theories of lanthanide nanostructures, synthesis techniques, and enhancement methods of upconversion for photovoltaic and for near-infrared (NIR) photodetector (PD) application. In addition, a few examples of lanthanide-doped nanostructures with improved performance were discussed, with particular emphasis on upconversion emission enhancement using coupling plasmon. The use of UC materials has been shown to significantly improve the NIR light-harvesting properties of photovoltaic devices and photocatalytic materials. However, the inefficiency of UC emission also prompted the need for additional modification of the optical properties of UC material. This improvement entailed the proper selection of the host matrix and optimization of the sensitizer and activator concentrations, followed by subjecting the UC material to surface-passivation, plasmonic enhancement, or doping. As expected, improving the optical properties of UC materials can lead to enhanced efficiency of PDs and photovoltaic devices.

Performance Evaluation of Ultrasonic Imaging System (Part I)

Background:

Diagnostic ultrasound or sonography is an image which can provide valuable information for diagnosing and treating a variety of diseases and conditions. This experiment was done to check the performance and evaluate the ultrasonic imaging system. There were three tests performed in this experiment: dead zone (transducer ring-down), vertical measurement calibration, and horizontal measurement calibration.

Methods:

The evaluation was made by performed all the tests with different depth on two different multipurpose phantom model #539. The tests were also performed by two different probes which were curved and flat (linear probe). The images were taken, and the measurements were made by electronic calipers on the ultrasound machine system. Observations and evaluations were done via all images and measurements taken.

Results:

The images formed by two various probes were different. The penetration settings were different since the depths were different. The depth influenced the penetrations to the formed image. From the comparison of all results and measurements recorded were all under the accepted value of the standard that was given by the manufacture of the phantom.

Conclusion:

Therefore, it can be concluded that the measurements were all not exceeding 2% of the standard value given based on the result that we get.

Recent Advances in Synthesis, Medical Applications and Challenges for Gold-Coated Iron Oxide: Comprehensive Study

Combining iron oxide nanoparticles (Fe3O4 NPs) and gold nanoparticles (Au NPs) in one nanostructure is a promising technique for various applications. Fe3O4 NPs have special supermagnetic attributes that allow them to be applied in different areas, and Au NPs stand out in biomaterials due to their oxidation resistance, chemical stability, and unique optical properties. Recent studies have generally defined the physicochemical properties of nanostructures without concentrating on a particular formation strategy. This detailed review provides a summary of the latest research on the formation strategy and applications of Fe3O4@Au. The diverse methods of synthesis of Fe3O4@Au NPs with different basic organic and inorganic improvements are introduced. The role and applicability of Au coating on the surface of Fe3O4 NPs schemes were explored. The 40 most relevant publications were identified and reviewed. The versatility of combining Fe3O4@Au NPs as an option for medical application is proven in catalysis, hyperthermia, biomedical imaging, drug delivery and protein separation.

Recent Advances in Inorganic Nanomaterials Synthesis Using Sonochemistry: A Comprehensive Review on Iron Oxide, Gold and Iron Oxide Coated Gold Nanoparticles

Sonochemistry uses ultrasound to improve or modify chemical reactions. Sonochemistry occurs when the ultrasound causes chemical effects on the reaction system, such as the formation of free radicals, that intensify the reaction. Many studies have investigated the synthesis of nanomaterials by the sonochemical method, but there is still very limited information on the detailed characterization of these physicochemical and morphological nanoparticles. In this comprehensive review, recent advances in the sonochemical synthesis of nanomaterials based on iron oxide nanoparticles (Fe3O4NP), gold nanoparticles (AuNP) and iron oxide-coated gold nanoparticles (Fe3O4@Au NP) are discussed. These materials are the most studied materials for various applications, such as medical and commercial uses. This review will: (1) address the simple processing and observations on the principles of sonochemistry as a starting point for understanding the fundamental mechanisms, (2) summarize and review the most relevant publications and (3) describe the typical shape of the products provided in sonochemistry. All in all, this review's main outcome will provide a comprehensive overview of the available literature knowledge that promotes and encourages future sonochemical work.

Scenario analysis of COVID-19 transmission dynamics in Malaysia with the possibility of reinfection and limited medical resources scenarios

COVID-19 is a major health threat across the globe, which causes severe acute respiratory syndrome (SARS), and it is highly contagious with significant mortality. In this study, we conduct a scenario analysis for COVID-19 in Malaysia using a simple universality class of the SIR system and extensions thereof (i.e., the inclusion of temporary immunity through the reinfection problems and limited medical resources scenarios leads to the SIRS-type model). This system has been employed in order to provide further insights on the long-term outcomes of COVID-19 pandemic. As a case study, the COVID-19 transmission dynamics are investigated using daily confirmed cases in Malaysia, where some of the epidemiological parameters of this system are estimated based on the fitting of the model to real COVID-19 data released by the Ministry of Health Malaysia (MOH). We observe that this model is able to mimic the trend of infection trajectories of COVID-19 pandemic in Malaysia and it is possible for transmission dynamics to be influenced by the reinfection force and limited medical resources problems. A rebound effect in transmission could occur after several years and this situation depends on the intensity of reinfection force. Our analysis also depicts the existence of a critical value in reinfection threshold beyond which the infection dynamics persist and the COVID-19 outbreaks are rather hard to eradicate. Therefore, understanding the interplay between distinct epidemiological factors using mathematical modelling approaches could help to support authorities in making informed decisions so as to control the spread of this pandemic effectively.

Focused role of nanoparticles against COVID-19: Diagnosis and treatment

The 2019 novel coronavirus (2019-nCoV; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)) has witnessed a rapid and global proliferation since its early identification in patients with severe pneumonia in Wuhan, China. As of 27th May 2020, 2019-nCoV cases have risen to >5 million, with confirmed deaths of 350,000. However, Coronavirus disease (COVID-19) diagnostic and treatment measures are yet to be fully unraveled, given the novelty of this particular coronavirus. Therefore, existing antiviral agents used for severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) were repurposed for COVID-19, taking their biological features into consideration. This study provides a concise review of the current and emerging detection and supervision technologies for SARS-CoV-2, which is the viral etiology of COVID19, and their performance characteristics, with emphasis on the novel Nano-based diagnostic tests (protein corona sensor array and magnetic levitation) and treatment measures (treatment protocols based on nano-silver colloids) for COVID-19.

Potential of a sonochemical approach to generate MRI-PPT theranostic agents for breast cancer

The production of nanomaterials integrating diagnostic and therapeutic roles within one nanoplatform is important for medical applications. Such theranostics nanoplatforms could provide information on imaging, accurate diagnosis and, at the same time, could eradicate cancer cells. Fe₃O₄@Au core@shell nanoparticles (Fe₃O₄@AuNPs) have gained broad attention due to their unique innovations in magnetic resonance imaging (MRI) and photothermal therapy (PTT). Seed-mediated growth procedures were used to produce the Fe₃O₄@AuNPs. In these processes, complicated surface modifications, resulted in unsatisfactory properties. This work used the ability of the sonochemical approach to synthesize highly efficient theranostics agent Fe₃O₄@AuNPs with a size of approximately 22 nm in 5 min. The inner core of Fe₃O₄ acts as an MRI agent, whereas the photothermal effect stands accomplished by near-infrared absorption of the gold shell (Au shell), which results in the eradication of cancer cells. We have shown that Fe₃O₄@AuNPs have great biocompatibility and no major cytotoxicity has been identified. Relaxivity value (r₂) of synthesized Fe₃O₄@Au NPs, measured at 233 mM^-1s^-1, is significantly higher than those reported previously. The as-synthesized NPs have shown substantial photothermal ablation ability on MCF-7 in vitro under near-infrared laser irradiation. Consequently, Fe₃O₄@AuNPs synthesized in this study have great potential as an ideal candidate for MR imaging and PTT.

Simple rapid stabilization method through citric acid modification for magnetite nanoparticles

A highly stable and magnetized citric acid (CA)-functionalized iron oxide aqueous colloidal solution (Fe3O4@CA) was synthesized by using a simple and rapid method of one-step co-participation via a chemical reaction between Fe3+ and Fe2+ in a NaOH solution at 65 °C, followed by CA addition to functionalize the Fe3O4 surface in 25 min. The NPs were synthesized at lower temperatures and shortened time compared with conventional methods. Surface functionalization is highly suggested because bare Fe3O4 nanoparticles (Fe3O4 NPs) are frequently deficient due to their low stability and hydrophilicity. Hence, 19 nm-sized Fe3O4 NPs coated with CA (Fe3O4@CA) were synthesized, and their microstructure, morphology, and magnetic properties were characterized using X-ray diffraction, transmission electron microscopy, Zeta potential, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. CA successfully modified the Fe3O4 surface to obtain a stabilized (homogeneous and well dispersed) aqueous colloidal solution. The Zeta potential value of the as-prepared Fe3O4@CA increases from - 31 to - 45 mV. These CA-functionalized NPs with high magnetic saturation (54.8 emu/g) show promising biomedical applications.

Trastuzumab conjugated porphyrin-superparamagnetic iron oxide nanoparticle: A potential PTT-MRI bimodal agent for herceptin positive breast cancer

BACKGROUND

Theranostic agents can combine photosensitizers and contrast agents into a single unit for photothermal therapy (PTT) and magnetic resonance imaging (MRI). The possibility of treating and diagnosing malignant cancers without any ionizing radiation could become an option. This study investigates the theranostic potential of Fe₃O₄ nanoparticles (IONs) for the diagnosis and treatment of cancer by developing a single integrated nanoprobe.

METHODS

Oleylamin-coated IONs (ION-Ol) were synthesized and surface of the IONs was modified using protoporphyrin (PP) and trastuzumab (TZ) to develop the TZ-conjugated SPION-porphyrin [ION-PP-TZ]. The structure, morphology, size, and cytotoxicity of all samples were investigated using Fourier-transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), X-ray powder diffraction (XRD), WST-1 assay, respectively. In addition to MRI and in vitro laser irradiation (808 nm, 200 mW) to determine the r₂ values and photothermal ablation.

RESULTS

The sizes of monodispersed nanoparticles were measured in rang 5.74-7.17 nm. No cytotoxicity was observed after incubating MCF 7 cells under various Fe concentrations of nanoparticles and theranostic agents. The transverse relaxation time of the protoporphyrin conjugated to IONs (52.32 mM^-1s^-1) exceeded that of ION-Ol and TZ-conjugated ION-PP. In addition, the in vitro photothermal ablation of ION-PP-TZ revealed a 74 % MCF 7 cell reduction after 10 min of at the highest Fe concentration (1.00 mg Fe/mL).

CONCLUSIONS

In summary, the water-soluble ION-PP-TZ is a promising bimodal agent for the diagnosis and treatment of human epidermal growth factor receptor 2-positive breast cancer cells using a T₂ MRI contrast agent and photothermal therapy.

Mechanisms of effective gold shell on Fe3O4 core nanoparticles formation using sonochemistry method

Sonochemical synthesis (sonochemistry) is one of the most effective techniques of breaking down large clusters of nanoparticles (NPs) into smaller clusters or even individual NPs, which ensures their dispersibility (stability) in a solution over a long duration. This paper demonstrates the potential of sonochemistry becoming a valuable tool for the deposition of gold (Au) shell on iron oxide nanoparticles (Fe₃O₄ NPs) by explaining the underlying complex processes that control the deposition mechanism. This review summarizes the principles of the sonochemistry method and highlights the resulting phenomenon of acoustic cavitation and its associated physical, chemical and thermal effects. The effect of sonochemistry on the deposition of Au NPs on the Fe₃O₄ surface of various sizes is presented and discussed. A Vibra-Cell ultrasonic solid horn with tip size, frequency, power output of ½ inch, 20 kHz and 750 W respectively was used in core@shell synthesis. The sonochemical process was shown to affect the surface and structure of Fe₃O₄ NPs via acoustic cavitation, which prevents the agglomeration of clusters in a solution, resulting in a more stable dispersion. Deciphering the mechanism that governs the formation of Au shell on Fe₃O₄ core NPs has emphasized the potential of sonication in enhancing the chemical activity in solutions.