This work is supported by the Department of Science and Technology - Philippine Textile Research Institute under the DOST Grants-in-Aid (DOST-GIA) Project entitled Covert Technology Towards Sustainability and Protection of the Philippine Textile Sectors under the Digitalization of the Philippine Handloom Weaving Industry Program.

1. Extraction of curcumin
<ol>
	<li>Weigh 3 g of C. longa powder in a 50 mL centrifuge tube. 
	NOTE: A 50 mL centrifuge tube was used to ease the centrifugation process and process the extraction on a single container.</li>
	<li>Add 38 mL of ethanol (AR, 99%) to the centrifuge tube. Shake the tube gently to ensure thorough mixing of ethanol with the C. longa powder.</li>
	<li>Sonicate the tube for 30 min at normal sonic mode and high intensity setting for extraction.</li>
	<li>To separate the solid materials, centrifuge the tube at 4430 x g for 10 min. Before using the centrifuge, open the tube and close it again to depressurize and prevent leakage.</li>
	<li>Decant to collect the supernatant and store it in dry, ambient conditions. The supernatant contains curcumin extract in ethanol solvent. It is important to keep the container closed to prevent solvent leakage.</li>
</ol>
2. Fourier transform infrared ( FTIR) characterization of C. longa extract
NOTE: Attenuated total reflectance- Fourier transform infrared (ATR-FTIR) spectrophotometer was operated following standard procedures found in the user manual.
<ol>
	<li>Before measuring the IR spectra, the measurement parameters must be set. Use the Measure option, click on the Advanced tab and set the parameters for the sample and background scan time to 40 scans, scan resolution to 4 cm1, and the range from 4000 - 400 cm-1.</li>
	<li>Clean the ATR crystal with Propan-2-ol (99.8%). After cleaning, switch to Basic. 
	NOTE: Background scans are necessary to eliminate environmental interference, ensuring that the IR spectra exclusively represent the sample being analyzed. Background measurements are only performed before starting the operation of the instrument. Cleaning the ATR crystal should always take place before every new measurement.</li>
	<li>Use a Pasteur pipette to apply 0.3 mL of crude C. longa extract into the ATR crystal and let it dry for 3 to 5 min to remove the interference of ethanol.As the ethanol dries, the extract consequently accumulates to the crystal which reduces the transmittance reading.</li>
	<li>On the software, click Measure &#62; Advanced to set the file name. After naming the sample, click on Basic tab and measure the IR transmittance of dried extract.</li>
	<li>Repeat steps 2.3 and 2.4 up to 3x or until the resolution of the spectra improves. 
	NOTE: An improved resolution is determined by a decrease in transmittance in the spectrum.</li>
	<li>After completing the reading, clean the ATR crystal using 99% ethanol and lint-free wipes. Subsequently, clean the ATR sample stage using Propan-2-ol.</li>
</ol>
3. UV-visible measurement of C. longa extract
NOTE: The UV-visible spectrophotometer was operated following standard procedures found in the user manual.
<ol>
	<li>Before measuring the samples, allow the instrument to warm up for 15 to 30 min. This will stabilize the light source and detector, thereby ensuring reproducible readings. Fill the reference cell with ethanol.</li>
	<li>Before measuring the absorption spectra, set the measurement parameters. Use the Setup option, click the Cary tab, and set the scan time to 0.1 s, data interval to 1 nm, and scan rate to 600 nm/min. Finally, set the range from 200 nm to 700 nm.</li>
	<li>Prepare 25 mL dilutions of C. longa extract ranging from 1:1000 to 1:100 with 1:100 increments using ethanol as a solvent.</li>
	<li>Transfer approximately 3.5 mL of diluted C. longa into a quartz cuvette using a Pasteur pipette. For easier cleaning after each sample measurement, begin with 1:1000 dilution and work up to 1:100.</li>
	<li>Measure absorbance of the extract as described below.
	<ol>
		<li>Clean the cuvette with ethanol and repeat the measurements for the other dilutions.</li>
		<li>To ensure the accuracy of absorption, rinse the cuvettes thoroughly with the diluted extract before transferring the test solution.</li>
	</ol>
	</li>
	<li>Repeat steps 3.4-3.5.2 for other concentrations.</li>
</ol>
4. Photoluminescence measurement of C. longa extract
NOTE: The operation of the fluorescence spectrometer followed standard procedures found in the user manual.
<ol>
	<li>Before measuring the samples, allow the instrument to warm up for 15 to 30 min. This will stabilize the light source and detector, thereby ensuring the reproducibility of each measurement.</li>
	<li>Before measuring the fluorescent spectra, first set the measurement parameters. Click the Measure button and set the integration time to 0.1 s, increments to 1 nm, and slit width to 1 nm. The measurement range may vary depending on the excitation or emission source.</li>
	<li>Using a Pasteur pipette, carefully transfer around 3.5 mL of diluted C. longa in the quartz cuvette. To facilitate easier cleaning after sample measurement, start the measurement from 1:1000 up to 1:100.</li>
	<li>Measure the emission of the extract using a 365 nm excitation source. Set the emission range from 380 nm to 625 nm.</li>
	<li>Using the wavelength with the highest emission from step 4.4, measure the excitation spectrum of the sample. Set the lower limit for the excitation range to 330 nm and calculate the upper limit using the monitored emission wavelength minus 15 nm. The allowance of 15 nm ensures that no first-order scattering will be observed on the spectra.</li>
	<li>Using the wavelength with the highest excitation from step 4.5, measure the emission spectrum of the sample again. Calculate the lower limit for emission range using the excitation wavelength plus 15 nm. Set the upper limit to 625 nm.</li>
	<li>Measure the emission-excitation matrix of C. longa extract as described below.
	<ol>
		<li>For consistency, set the measuring range for excitation from 330-435 nm and the emission to 450-650 nm. Maintain these parameters for all concentrations.</li>
		<li>Clean the cuvette with ethanol and repeat the measurements for other dilutions. To ensure the accuracy of fluorescence measurements, rinse the cuvettes with the diluted extract before transferring the test solution.</li>
	</ol>
	</li>
</ol>
5. Photoluminescence measurement of chitosan
<ol>
	<li>Prepare 300 mL of 1% w/v solution of Chitosan. Mix 3 g of chitosan to 1% v/v acetic acid (99.8%) solution until it reaches 300 mL. Stir the solution for 24 h or until it homogenizes.</li>
	<li>Measure the emission-excitation matrix of Chitosan as described below.
	<ol>
		<li>Use the following measuring parameters for chitosan: 
		Slit width: 1 nm (both emission and excitation) 
		Integration time: 0.1 s 
		Emission range: 300-370 nm 
		&#8203;Excitation range: 385-450 nm</li>
	</ol>
	</li>
	<li>Measure the IR spectra of fabrics as described below.
	<ol>
		<li>Place the multi-tester fabric (Fabric #1) above the ATR crystal. The multi-tester fabric contains six types of fabric shown in Figure 1A. When measuring using ATR-FTIR, make sure the whole ATR crystal is covered with the sample. The fabric should make full contact with the ATR crystal by pulling the lever of the sample presser. This will decrease the transmittance it collects.</li>
		<li>Measure the IR transmittance of the fabrics. Repeat the measurement on other fabrics.</li>
	</ol>
	</li>
</ol>
6. Dyeing of fabrics
<ol>
	<li>Weigh the fabrics to determine the amount of dye and chitosan finishing to be used.</li>
	<li>Prepare C. longa extract solutions at dilutions 1:1, 1:10, 1:50, 1:100, 1:500, and 1:1000 using 99% ethanol.</li>
	<li>Dye the fabrics with diluted C. longa extract at a 1:25 material-liquor ratio for 1 h by soaking the fabric in the solutions.</li>
	<li>Hang the fabrics to dry. Rinse the fabrics with tap water and hang to dry.</li>
	<li>Carry out fabric finishing as described below.
	<ol>
		<li>Soak the dyed fabrics with 1% w/v Chitosan solution at a 1:40 material to liquor ratio for 1 h by soaking the fabric in the solution.</li>
		<li>Hang the fabrics to dry. Rinse the fabrics with tap water and hang to dry.</li>
	</ol>
	</li>
</ol>
7. Photoluminescence measurements of dyed fabrics
<ol>
	<li>Place the fabric in the sample holder. When using AATCC multi-tester fabrics, ensure that the tested fabric is placed in the middle of the window and no other fabrics are within the measurement area. To fix the position of fabrics, use glass slides as support. An example of the positioning of fabric is shown in Figure 1.</li>
	<li>For measurement of fabric photoluminescence, set the integration time to 0.1 s, increments to 1 nm, and slit width to 0.6 nm. Measure the fluorescence of dyed fabrics at 365 nm excitation. Similar to measuring solutions, set the emission range to 380-625 nm.</li>
	<li>Using the wavelength with the highest emission from step 5.3, measure the excitation spectrum of the sample. Set the lower limit for the excitation range to 330 nm and calculate the upper limit for the excitation range using the monitored emission wavelength minus 15 nm. The allowance of 15 nm ensures that no first-order scattering will be observed on the spectra.</li>
	<li>Using the wavelength with the highest excitation from step 7.3, measure the emission spectrum of the sample. Calculate the lower limit for emission range using the excitation wavelength plus 15 nm. Set the upper limit to 625 nm.</li>
	<li>Repeat measurement step 7.1 to 7.4 for other types of sample fabrics and with different concentrations.</li>
	<li>Measure the emission spectra of 1:50 diluted Chitosan-finished C. longa extract-dyed fabrics using 365 nm excitation wavelength. 
	NOTE: The fabrics dyed with 1:50 dilution are used for the analysis of the effects of Chitosan finishing as it shows the highest photoluminescence. Similar to step 4.4, set the emission range from 380-625 nm.</li>
	<li>Collect the spectrochemical data for interpretation.</li>
</ol>
8. Morphological analysis of fabrics
NOTE: Morphological analysis of fabrics involves two types of lighting: white light and 365 nm UV light. The choice of light source can reveal how the dye and finishing adhere to the fabric.
<ol>
	<li>Since the microscope lacks a UV light source, use a handheld 365 nm UV light source. Fix the light source securely to maintain a consistent position without affecting the imaging process. Use a clamp attached to an iron stand to mount the 365 nm UV light, pointing it toward the stereo zoom microscope stage.</li>
	<li>Place the fabric on the stage and open the white light source. Use the coarse adjustment knob to set the zoom to its lowest magnification and locate the target imaging area. Gradually increase the magnification up to 4x and refine it using the fine adjustment knob.</li>
	<li>Utilize the built-in imaging software to insert a scale bar and capture the image.</li>
	<li>To ensure consistent imaging, configure the exposure parameters with the following values: set exposure compensation to 100, exposure time to 100 ms, and gain to 20. Additionally, adjust the hue values to red: 27, green: 32, and blue: 23. Other specified parameters requiring adjustment include sharpness: 75, denoise: 35, saturation: 50, gamma: 6, and contrast: 50.</li>
	<li>Turn OFF the white light source and switch on the 365 nm light source. Capture an image using the same imaging parameters.</li>
	<li>Repeat steps 8.3 to 8.6 for all types of fabrics and conditions (blank, dyed, finishing only, dyed and finished) until images of all the fabrics are captured. In total, there should be 48 images of fabrics.</li>
</ol>

Use of Chitosan to Enhance Photoluminescence of Curcumin for Textile Authentication

The authors have nothing to disclose.

Textile finishing is a common practice within the industry in order to incorporate additional functional properties onto the fabrics, making them more suitable for specific applications45,47,48. In this study, the extracted curcumin was utilized as a natural dye to serve as authentication mechanisms for textile applications. The protocols give emphasis not only to the extraction of curcumin from turmeric, but also to the differe...

Counterfeiting is considered a scourge in widespread industries across the globe. The rapid surge of counterfeit products in the market causes economic havoc, which impedes the livelihood of the primary inventor1,2,3,4,5,6. This was brought to the fore in 20207&#160;on the ongoing concern of emerging counterfeit products as evidenced by the increasing trend of publications consisting of the keyword anticounterfeiting or counterfeiting in their titles. A significant increase can be observed in counterfeit-related publications since last reported in 2019, suggesting that considerable efforts are being made to combat the production and distribution of fraudulent goods. On the other hand, it can also be quite alarming, given that it signifies the progression of the counterfeiting industry, which is expected to persist if not addressed effectively. The textile industry is not insulated from this problem, as the presence of counterfeit textile products has severely impacted the livelihood of genuine sellers, manufacturers and weavers, among others3,8. For instance, the textile industry in West Africa was long considered one of the leading export markets in the world. However, it was reported9&#160;that approximately 85% of the market share is held by smuggled textiles that infringe upon West African textile trademarks. The effects of counterfeiting have also been reported in other continents like Asia, America, and Europe, indicating that this crisis has reached an uncontrollable level and poses a significant threat to the already struggling textile industry2,3,4,10,11,12.
With the rapid advancements of science, technology, and innovation, researchers took upon the role of developing functional materials for the purpose of anti-counterfeiting applications. The use of covert technology is one of the most common and effective approaches to counteract the production of fraudulent goods. It involves utilizing photoluminescent materials as security dyes that exhibit a specific light emission when irradiated by different wavelengths13,14. However, some photoluminescent dyes available in the market may impose toxicity at high concentrations, thereby posing threats to human health and the environment15,16.
Turmeric (Curcuma longa) is an essential plant used in myriad applications such as paints, flavoring agents, medicine, cosmetics, and fabric dyes17. Present in the rhizomes are naturally occurring phenolic chemical compounds called curcuminoids. These curcuminoids include curcumin, demethoxycurcumin, and bisdemethoxycurcumin, among which curcumin is the main constituent responsible for the vibrant yellow to orange coloration and the properties of turmeric18. Curcumin, otherwise known as 1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione19,20&#160;with an empirical formula of C21H20O6, has attracted a significant amount of attention in the biomedical and pharmaceutical fields due to its antiseptic, anti-inflammatory, anti-bacterial, and antioxidant properties17,18,21,22,23. Interestingly, curcumin also possesses spectral and photochemical characteristics. Particularly noteworthy is its intense photoluminescent properties when subjected to ultraviolet (UV) excitations which have been explored only by a few studies19,24,25. Given these characteristics, in tandem with its hydrophobic nature and non-toxic properties, curcumin emerges as an ideal colorant for authentication markings.
The extraction of curcumin from turmeric was first reported in the early 1800s. Over the past centuries, numerous extraction methodologies and techniques have been devised and improved to achieve higher yield26,27,28,29,30,31,32,33. Conventional solvent extraction is a widely used approach as it employs organic solvents such as ethanol, methanol, acetone, and hexane among others, to isolate curcumin from turmeric34,35. This method has evolved through modifications, coupled with more advanced techniques such as microwave-assisted extraction (MAE)18,36,37, Soxhlet extraction38,39, enzyme-assisted extraction (EAE)39,40, and ultrasonic extraction36, among others to increase the yield. Generally, the solvent extraction method has been applied for natural dye extraction due to its versatility, low energy requirement, and cost-effectiveness making it ideal for scalable industries such as textiles.
Curcumin has been integrated as natural dyes for textiles due to its distinct yellow hue. However, the poor adsorption of natural dyes unto textile fibers pose as a challenge that hinders its commercial viability41. Mordants, such as metals, polysaccharides, and other organic compounds, serve as common binders to strengthen the affinity of natural dyes unto the fabric. Chitosan, a polysaccharide derived from crustaceans, has been widely utilized as an alternative mordanting agent due to its abundance in nature, biocompatibility, and wash durability42. This study reports a facile and straight forward approach in preparing curcumin-based authentication marking. Crude curcumin extracts were obtained via sonication-assisted solvent extraction method. The photoluminescent properties of the extracted curcumin were comprehensively investigated on textile substrates and further enhanced with the introduction of chitosan as a mordanting agent. This demonstrates the significant potential as a naturally derived photoluminescent dye for authentication applications.

<table><tbody><tr><td>(Curcumin) &lt;em&gt;C. longa&lt;/em&gt;, spray dried&amp;nbsp;</td><td>N/A</td><td>N/A</td><td>Naturally Sourced</td></tr><tr><td>100 mL Graduated Cylinder</td><td>n/a</td><td></td><td></td></tr><tr><td>10 mL Serological Pipette</td><td>n/a</td><td></td><td></td></tr><tr><td>200 mL Beaker</td><td>n/a</td><td></td><td></td></tr><tr><td>365 nm UV Light</td><td>AloneFire</td><td></td><td>SV004 LG</td></tr><tr><td>50 mL Centeifuge Tube</td><td>n/a</td><td></td><td></td></tr><tr><td>AATCC Multitester Fabric</td><td>Testfabrics, Inc.</td><td>401002</td><td>AATCC Multifiber test fabric # 1 precut pieces of 2 X 2 inches, Heat Sealed</td></tr><tr><td>Analytical Balance</td><td>Satorius</td><td></td><td>BSA 224S-CW</td></tr><tr><td>Aspirator</td><td>n/a</td><td></td><td></td></tr><tr><td>ATR- FTIR</td><td>Bruker</td><td></td><td>Bruker Tensor II</td></tr><tr><td>Centrifuge</td><td>Hermle Labortechnik GmbH</td><td></td><td>Z 206 A</td></tr><tr><td>Chitosan</td><td>Tokyo Chemical Industries</td><td>9012-76-4</td><td></td></tr><tr><td>Digital&amp;nbsp; Camera</td><td>ToupTek</td><td></td><td>XCAM1080PHB</td></tr><tr><td>Drying Rack</td><td>n/a</td><td></td><td></td></tr><tr><td>Ethanol</td><td>Chem-Supply</td><td>64-17-5</td><td>Undenatured, 99.9% purity</td></tr><tr><td>Glacial Acetic Acid</td><td>RCI-Labscan</td><td>64-19-7</td><td>AR Grade, 99.8% purity</td></tr><tr><td>Glass Slide</td><td>n/a</td><td></td><td></td></tr><tr><td>Iron Clamp</td><td>n/a</td><td></td><td></td></tr><tr><td>Iron Stand</td><td>n/a</td><td></td><td></td></tr><tr><td>Magnetic Stirrer</td><td>Corning</td><td></td><td>PC-620D</td></tr><tr><td>Pasteur Pipette</td><td>n/a</td><td></td><td></td></tr><tr><td>Propan-2-ol</td><td>RCI-Labscan</td><td>67-63-0</td><td>AR Grade, 99.8% purity</td></tr><tr><td>Sonicator</td><td>Jeio Tech Inc.</td><td></td><td>UCS-20</td></tr><tr><td>Spectrofluorometer&amp;nbsp;</td><td>Horiba (Jovin Yvon)</td><td></td><td>Horiba Fluoromax Plus</td></tr><tr><td>Stirring Bar</td><td>n/a</td><td></td><td></td></tr><tr><td>UV-Vis Spectrophotometer</td><td>Agilent</td><td></td><td>Cary UV 100</td></tr><tr><td>Wash bottle</td><td>n/a</td><td></td><td></td></tr><tr><td>Zoom Stereo Microscope</td><td>Olympus</td><td></td><td>SZ61</td></tr></tbody></table>

enhanced photoluminescence of curcuma longa extracts via chitosan-mediated energy transfer for textile authentication applications

Dyes for security markings play a pivotal role in safeguarding the integrity of products across various fields, such as textiles, pharmaceuticals, food, and manufacturing among others. However, most commercial dyes used as security markings are costly and may contain toxic and harmful substances that pose a risk to human health. Curcumin, a natural phenolic compound found in turmeric, possesses distinct photoluminescent properties alongside its vibrant yellow color, making it a potential candidate material for authentication applications. This study demonstrates a cost-effective and eco-friendly approach to develop enhanced photoluminescent emissions from curcumin dyes for textile authentication. Curcumin was extracted from C. longa using sonication-assisted-solvent extraction method. The extract was dip-coated and dyed into the textile substrates. Chitosan was introduced as a post-mordanting agent to stabilize the curcumin and as a co-sensitizer. Co-sensitization of curcumin with chitosan triggers energy transfer to enhance its luminescent intensity. The UV-visible absorption peak at 424 nm is associated with the characteristic absorption of curcumin. The photoluminescence measurements showed a broad emission peaking at 545 nm with significant enhancement attributed to the energy transfer induced by chitosan, thus showing great potential as a naturally derived photoluminescent dye for authentication applications.

FTIR analyses of fibers determine the chemical structure of each fiber represented in the multi-tester fabrics #1. FTIR spectroscopy was utilized in order to characterize the functional groups present in each component of the multi-test fabrics. As shown in Supplementary Figure 1, the distinction occurs due to the presence of N-H functional groups, which leads to the fabric being subcategorized into nitrogenous (Supplementary Figure 1A) ...

Watch this Scientific Journal Video about Enhanced Photoluminescence of Curcuma longa Extracts via Chitosan-Mediated Energy Transfer for Textile Authentication Applications at JoVE.com

Author Spotlight: Eco-friendly Photoluminescent Textile Authentication with Curcumin

Photoluminescence is one of the most effective authentication mechanisms being used today. Utilizing and enhancing naturally sourced materials with inherent photoluminescent properties and incorporating them into fabric substrates can lead to development of green, sustainable, and functional textiles for smart applications.

Enhanced Photoluminescence of Curcuma longa Extracts via Chitosan-Mediated Energy Transfer for Textile Authentication Applications

Dyes for security markings play a pivotal role in safeguarding the integrity of products across various fields, such as textiles, pharmaceuticals, food, ...

enhanced-photoluminescence-curcuma-longa-extracts-via-chitosan

Research

Education

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JoVE Journal

Analytical Chemistry

Chemistry

Unit 1

Introduction to Molecular Spectroscopy

SCIENTISTS IN ACTION

1.5K Views.  Smart Colorants R&D Program, Philippine Textile Research Institute. Photoluminescence is one of the most effective authentication mechanisms being used today. Utilizing and enhancing naturally sourced materials with inherent photoluminescent properties and incorporating them into fabric substrates can lead to development of green, sustainable, and functional textiles for smart applications. 

Video: Author Spotlight: Eco-friendly Photoluminescent Textile Authentication with Curcumin

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, 'SurgiLux': Preparation and Demonstration

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures can act as a nidus for infection and in many procedures are unable to effect wound repair or interfere with functional tissue regeneration.1 Surgical glues and adhesives, such as those based on fibrin and cyanoacrylates, have been developed as alternatives to sutures for the repair of such wounds. However, current commercial adhesives also have significant disadvantages, ranging from viral and prion transfer and a lack of repair strength as with the fibrin glues, to tissue toxicity and a lack of biocompatibility for the cyanoacrylate based adhesives. Furthermore, currently available surgical adhesives tend to be gel-based and can have extended curing times which limit their application.2 Similarly, the use of UV lasers to facilitate cross-linking mechanisms in protein-based or albumin 'solders' can lead to DNA damage while laser tissue welding (LTW) predisposes thermal damage to tissues.3 Despite their disadvantages, adhesives and LTW have captured approximately 30% of the wound closure market reported to be in excess of US $5 billion per annum, a significant testament to the need for sutureless technology.4
In the pursuit of sutureless technology we have utilized chitosan as a biomaterial for the development of a flexible, thin film, laser-activated surgical adhesive termed 'SurgiLux'. This novel bioadhesive uses a unique combination of biomaterials and photonics that are FDA approved and successfully used in a variety of biomedical applications and products. SurgiLux overcomes all the disadvantages associated with sutures and current surgical adhesives (see Table 1).
In this presentation we report the relatively simple protocol for the fabrication of SurgiLux and demonstrate its laser activation and tissue weld strength. SurgiLux films adhere to collagenous tissue without chemical modification such as cross-linking and through irradiation using a comparatively low-powered (120 mW) infrared laser instead of UV light. Chitosan films have a natural but weak adhesive attraction to collagen (~3 KPa), laser activation of the chitosan based SurgiLux films emphasizes the strength of this adhesion through polymer chain interactions as a consequence of transient thermal expansion.5 Without this 'activation' process, SurgiLux films are readily removed.6-9 SurgiLux has been tested both in vitro and in vivo on a variety of tissues including nerve, intestine, dura mater and cornea. In all cases it demonstrated good biocompatibility and negligible thermal damage as a consequence of irradiation.6-10

The fabrication of a novel, flexible thin film surgical adhesive from FDA approved ingredients, chitosan and indocyanine green is described. Bonding of this adhesive to collagenous tissue through a simple activation process with a low-powered infra-red laser is demonstrated.

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures ...

Bioengineering

Integrating a Triplet-triplet Annihilation Up-conversion System to Enhance Dye-sensitized Solar Cell Response to Sub-bandgap Light

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents and hence higher efficiencies. Photon up-conversion by way of triplet-triplet annihilation (TTA-UC) is an attractive technique for using these otherwise wasted low energy photons to produce photocurrent, while not interfering with the photoanodic performance in a deleterious manner. Further to this, TTA-UC has a number of features, distinct from other reported photon up-conversion technologies, which renders it particularly suitable for coupling with DSC technology. In this work, a proven high performance TTA-UC system, comprising a palladium porphyrin sensitizer and rubrene emitter, is combined with a high performance DSC (utilizing the organic dye D149) in an integrated device. The device shows an enhanced response to sub-bandgap light over the absorption range of the TTA-UC sub-unit resulting in the highest figure of merit for up-conversion assisted DSC performance to date.

An integrated device, incorporating a dye-sensitized solar cell and triplet-triplet annihilation up-conversion unit was produced, affording enhanced light harvesting, from a wider section of the solar spectrum. Under modest irradiation levels a significantly enhanced response to low energy photons was demonstrated, yielding a record figure of merit for dye-sensitized solar cells.

The poor response of dye-sensitized solar cells (DSCs) to red and infrared light is a significant impediment to the realization of higher photocurrents ...

Engineering

Bridging the Bio-Electronic Interface with Biofabrication

Advancements in lab-on-a-chip technology promise to revolutionize both research and medicine through lower costs, better sensitivity, portability, and higher throughput. The incorporation of biological components onto biological microelectromechanical systems (bioMEMS) has shown great potential for achieving these goals. Microfabricated electronic chips allow for micrometer-scale features as well as an electrical connection for sensing and actuation. Functional biological components give the system the capacity for specific detection of analytes, enzymatic functions, and whole-cell capabilities. Standard microfabrication processes and bio-analytical techniques have been successfully utilized for decades in the computer and biological industries, respectively. Their combination and interfacing in a lab-on-a-chip environment, however, brings forth new challenges. There is a call for techniques that can build an interface between the electrode and biological component that is mild and is easy to fabricate and pattern.
Biofabrication, described here, is one such approach that has shown great promise for its easy-to-assemble incorporation of biological components with versatility in the on-chip functions that are enabled. Biofabrication uses biological materials and biological mechanisms (self-assembly, enzymatic assembly) for bottom-up hierarchical assembly. While our labs have demonstrated these concepts in many formats 1,2,3, here we demonstrate the assembly process based on electrodeposition followed by multiple applications of signal-based interactions. The assembly process consists of the electrodeposition of biocompatible stimuli-responsive polymer films on electrodes and their subsequent functionalization with biological components such as DNA, enzymes, or live cells 4,5. Electrodeposition takes advantage of the pH gradient created at the surface of a biased electrode from the electrolysis of water 6,7,. Chitosan and alginate are stimuli-responsive biological polymers that can be triggered to self-assemble into hydrogel films in response to imposed electrical signals 8. The thickness of these hydrogels is determined by the extent to which the pH gradient extends from the electrode. This can be modified using varying current densities and deposition times 6,7. This protocol will describe how chitosan films are deposited and functionalized by covalently attaching biological components to the abundant primary amine groups present on the film through either enzymatic or electrochemical methods 9,10. Alginate films and their entrapment of live cells will also be addressed 11. Finally, the utility of biofabrication is demonstrated through examples of signal-based interaction, including chemical-to-electrical, cell-to-cell, and also enzyme-to-cell signal transmission. 
Both the electrodeposition and functionalization can be performed under near-physiological conditions without the need for reagents and thus spare labile biological components from harsh conditions. Additionally, both chitosan and alginate have long been used for biologically-relevant purposes 12,13. Overall, biofabrication, a rapid technique that can be simply performed on a benchtop, can be used for creating micron scale patterns of functional biological components on electrodes and can be used for a variety of lab-on-a-chip applications.

This article describes a biofabrication approach: deposition of stimuli-responsive polysaccharides in the presence of biased electrodes to create biocompatible films which can be functionalized with cells or proteins. We demonstrate a bench-top strategy for the generation of the films as well as their basic uses for creating interactive biofunctionalized surfaces for lab-on-a-chip applications.

Advancements in lab-on-a-chip technology promise to revolutionize both research and medicine through lower costs, better sensitivity, portability, and ...

Synthesis of Core-shell Lanthanide-doped Upconversion Nanocrystals for Cellular Applications

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical properties, which allow for the absorption of near-infrared (NIR) light and can subsequently convert it into multiplexed emissions that span over a broad range of regions from the UV to the visible to the NIR. This article presents detailed experimental procedures for high-temperature co-precipitation synthesis of core-shell UCNs that incorporate different lanthanide ions into nanocrystals for efficiently converting deep-tissue penetrable NIR excitation (808 nm) into a strong blue emission at 480 nm. By controlling the surface modification with biocompatible polymer (polyacrylic acid, PAA), the as-prepared UCNs acquires great solubility in buffer solutions. The hydrophilic nanocrystals are further functionalized with specific ligands (dibenzyl cyclooctyne, DBCO) for localization on the cell membrane. Upon NIR light (808 nm) irradiation, the upconverted blue emission can effectively activate the light-gated channel protein on the cell membrane and specifically regulate the cation (e.g., Ca2+) influx in the cytoplasm. This protocol provides a feasible methodology for the synthesis of core-shell lanthanide-doped UCNs and subsequent biocompatible surface modification for further cellular applications.

A protocol is presented for the synthesis of core-shell lanthanide-doped upconversion nanocrystals (UCNs) and their cellular applications for channel protein regulation upon near-infrared (NIR) light illumination.

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical ...

Luminescence Resonance Energy Transfer to Study Conformational Changes in Membrane Proteins Expressed in Mammalian Cells

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range of 10-100 &#197;. By measuring the distances under various ligated conditions, conformational changes of the protein can be easily assessed. With LRET, a lanthanide, most often chelated terbium, is used as the donor fluorophore, affording advantages such as a longer donor-only emission lifetime, the flexibility to use multiple acceptor fluorophores, and the opportunity to detect sensitized acceptor emission as an easy way to measure energy transfer without the risk of also detecting donor-only signal. Here, we describe a method to use LRET on membrane proteins expressed and assayed on the surface of intact mammalian cells. We introduce a protease cleavage site between the LRET fluorophore pair. After obtaining the original LRET signal, cleavage at that site removes the specific LRET signal from the protein of interest allowing us to quantitatively subtract the background signal that remains after cleavage. This method allows for more physiologically relevant measurements to be made without the need for purification of protein.

We describe here an improved Luminescence Resonance Energy Transfer (LRET) method where we introduce a protease cleavage site between the donor and acceptor fluorophore sites. This modification allows us to obtain specific LRET signals arising from membrane proteins of interest, allowing for the study of membrane proteins without protein purification.

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range ...

Combining QD-FRET and Microfluidics to Monitor DNA Nanocomplex Self-Assembly in Real-Time

Advances in genomics continue to fuel the development of therapeutics that can target pathogenesis at the cellular and molecular level. Typically functional inside the cell, nucleic acid-based therapeutics require an efficient intracellular delivery system. One widely adopted approach is to complex DNA with a gene carrier to form nanocomplexes via electrostatic self-assembly, facilitating cellular uptake of DNA while protecting it against degradation. The challenge lies in the rational design of efficient gene carriers, since premature dissociation or overly stable binding would be detrimental to the cellular uptake and therapeutic efficacy. Nanocomplexes synthesized by bulk mixing showed a diverse range of intracellular unpacking and trafficking behavior, which was attributed to the heterogeneity in size and stability of nanocomplexes. Such heterogeneity hinders the accurate assessment of the self-assembly kinetics and adds to the difficulty in correlating their physical properties to transfection efficiencies or bioactivities. We present a novel convergence of nanophotonics (i.e. QD-FRET) and microfluidics to characterize the real-time kinetics of the nanocomplex self-assembly under laminar flow. QD-FRET provides a highly sensitive indication of the onset of molecular interactions and quantitative measure throughout the synthesis process, whereas microfluidics offers a well-controlled microenvironment to spatially analyze the process with high temporal resolution (~milliseconds). For the model system of polymeric nanocomplexes, two distinct stages in the self-assembly process were captured by this analytic platform. The kinetic aspect of the self-assembly process obtained at the microscale would be particularly valuable for microreactor-based reactions which are relevant to many micro- and nano-scale applications. Further, nanocomplexes may be customized through proper design of microfludic devices, and the resulting QD-FRET polymeric DNA nanocomplexes could be readily applied for establishing structure-function relationships. 

We present a novel and powerful integration of nanophotonics (QD-FRET) and microfluidics to investigate the formation of polyelectrolyte polyplexes, which is expected to provide better control and synthesis of uniform and customizable polyplexes for future nucleic acid-based therapeutics.

Advances in genomics continue to fuel the development of therapeutics that can target pathogenesis at the cellular and molecular level. Typically ...

Biology

A Novel Technique for Generating and Observing Chemiluminescence in a Biological Setting

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are quickly moving into the operating room. Here, we present a new approach that utilizes a technique not yet explored for intraoperative imaging: chemiluminescent imaging. This method employs a ruthenium-based chemiluminescent reporter along with a custom-built nebulizing system to produce ex vivo or in vivo images with high signal-to-noise ratios. The ruthenium-based reporter produces light following exposure to an aqueous oxidizing solution and re-reduction within the surrounding tissue. This method has allowed us to detect reporter concentrations as low as 6.9 pmol/cm2. In this work, we present a visual guide to our proof-of-concept in vivo studies involving subdermal and intravenous injections in mice. The results suggest that this technology is a promising candidate for further preclinical research and might ultimately become a useful tool in the operating room.

This protocol describes a new intraoperative imaging technique that uses a ruthenium complex as a source of chemiluminescent light emission, thereby producing high signal-to-noise ratios during in vivo imaging. Intraoperative imaging is an expanding field that could revolutionize the way that surgical procedures are performed.

Intraoperative imaging techniques have the potential to make surgical interventions safer and more effective; for these reasons, such techniques are ...

Hydrothermal Synthesis of Persistent Luminescent Nanoparticles

Synthesis of Persistent Luminescent Nanoparticles for Rewritable Displays and Illumination Applications

Persistent luminescent nanoparticles (PLNPs) possess the capabilities to maintain extended longevity and robust emission even after the excitation has ceased. PLNPs have been widely used across various domains, including information displays, data encryption, biological imaging, and artistic decoration with sustained and vivid luminosity, providing boundless possibilities for a variety of innovative technology and artistic projects. This protocol focuses on an experimental procedure for the hydrothermal synthesis of PLNPs. The successful synthesis of enduring luminescent nanomaterials with Mn2+ or Cr3+ serving as a luminescent center in Zn2GeO4: Mn (ZGO: Mn) or ZnGa2O4: Cr highlights the universality of this synthetic method. On the other hand, the optical properties of ZGO: Mn can be changed by adjusting the pH of precursor solutions, demonstrating the tunability of the protocol. When charged with ultraviolet (UV) at a wavelength of 365 nm for 3 min and then stopped, PLNPs exhibit the remarkable capacity to generate afterglow efficiently and consistently, which makes them ideal for making two-dimensional rewritable displays and three-dimensional transparent, luminous artworks. This protocol outlined in this paper provides a feasible method for the synthesis of persistent luminescent nanoparticles for further illumination and imaging applications, opening up novel prospects for the fields of science and art.

Author Spotlight: Advancing Bioimaging and Therapy with Functional Nanomaterials

A protocol is presented for the synthesis of persistent luminescent nanomaterials (PLNPs) and their potential applications in rewritable displays and artistic processing utilizing the afterglow effect under ultraviolet light (365 nm) irradiation.

Persistent luminescent nanoparticles (PLNPs) possess the capabilities to maintain extended longevity and robust emission even after the excitation has ...

Effective aPDT Using Curcuminoids for Oral Candidiasis in Mice

Curcuminoid-Mediated Antimicrobial Photodynamic Therapy on a Murine Model of Oral Candidiasis

Antimicrobial Photodynamic Therapy (aPDT) has been extensively investigated in vitro, and preclinical animal models of infections are suitable for evaluating alternative treatments prior to clinical trials. This study describes the efficacy of aPDT in a murine model of oral candidiasis. Forty mice were immunosuppressed with subcutaneous injections of prednisolone, and their tongues were inoculated using an oral swab previously soaked in a C. albicans cell suspension. Tetracycline was administered via drinking water during the course of the experiment. Five days after fungal inoculation, mice were randomly distributed into eight groups; a ninth group of untreated uninfected mice was included as a negative control (n = 5). Three concentrations (20 &#181;M, 40 &#181;M, and 80 &#181;M) of a mixture of curcuminoids were tested with a blue LED light (89.2 mW/cm2; ~455 nm) and without light (C+L+ and C+L- groups, respectively). Light alone (C-L+), no treatment (C-L-), and animals without infection were evaluated as controls. Data were analyzed using Welch&#39;s ANOVA and Games-Howell tests (&#945; = 0.05). Oral candidiasis was established in all infected animals and visualized macroscopically through the presence of characteristic white patches or pseudomembranes on the dorsum of the tongues. Histopathological sections confirmed a large presence of yeast and filaments limited to the keratinized layer of the epithelium in the C-L- group, and the presence of fungal cells was visually decreased in the images obtained from mice subjected to aPDT with either 40 &#181;M or 80 &#181;M curcuminoids. aPDT mediated by 80 &#181;M curcuminoids promoted a 2.47 log10 reduction in colony counts in comparison to those in the C-L- group (p = 0.008). All other groups showed no statistically significant reduction in the number of colonies, including photosensitizer (C+L-) or light alone (C-L+) groups. Curcuminoid-mediated aPDT reduced the fungal load from the tongues of mice.

Author Spotlight: Exploring Photodynamic Therapy with Curcumin in a Murine Model for Oral Candidiasis

This protocol describes the application of antimicrobial Photodynamic Therapy (aPDT) in a murine model of oral candidiasis. aPDT was performed using a water-soluble mixture of curcuminoids and blue LED light.

Antimicrobial Photodynamic Therapy (aPDT) has been extensively investigated in vitro, and preclinical animal models of infections are suitable for ...

Immunology and Infection

Antimicrobial Efficacy of Nano-Herbal-Coated Fabrics

An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and burns. These cotton-based protective coats provide ideal conditions for microbial growth and attachment sites due to their porous nature, moisture-holding capacity, and retention of warmth from the user&#39;s body. Several studies have demonstrated the survival of pathogenic bacteria on hospital garments and lab coats, acting as vectors of microbial transmission.
A common approach to fix these problems is the application of antimicrobial agents in textile finishing, but concerns have been raised due to the toxicity and environmental effects of many synthetic chemicals. The ongoing pandemic has also opened a window for the investigation of effective antimicrobials and eco-friendly and toxic-free formulations. This study uses two natural bioactive compounds, carvacrol and thymol, encapsulated in chitosan nanoparticles, which guarantee effective protection against four human pathogens with up to a 4-log reduction (99.99%). These pathogens are frequently detected in lab coats used in biohazard laboratories.
The treated fabrics also resisted up to 10 wash cycles with 90% microbial reduction, which is sufficient for the intended use. We made modifications to the existing standard fabric tests to better represent the typical scenarios of lab coat usage. These refinements allow for a more accurate evaluation of the effectiveness of antimicrobial lab coats and for the simulation of the fate of any accidental microbial spills that must be neutralized within a short time. Further studies are recommended to investigate the accumulation of pathogens over time on antimicrobial lab coats compared to regular protective coats.

Author Spotlight: An Antimicrobial Fabric Using Nano-Herbal Encapsulation of Essential Oils  

Antimicrobial lab coats prevent the cross-contamination of pathogen accumulation and accidental bio-spills. Here, we describe the protocol for developing a skin-friendly antimicrobial fabric using nano-herbal encapsulation and modified standard tests to precisely evaluate the efficacy and suitability for typical usage of the lab coat.

Lab coats are widely used in biohazard laboratories and healthcare facilities as protective garments to prevent direct exposure to pathogens, spills, and ...