Adhesive composition comprising amylopectin and mastic gum

Abstract

The invention is based on an adhesive composition comprising amylopectin, mastic gum, and at least one solvent, such as water and / or an alcoholic solvent, for example ethanol, optionally further comprising glycerol and / or sodium chloride. The invention also pertains to an adhesive, obtainable from an adhesive composition according to this invention, wherein the adhesive is a conductive or a non-conductive adhesive. The invention also pertains to a method for preparing and / or obtaining an adhesive composition or an adhesive, and to an adhesive composition or an adhesive obtainable by the method according to this invention. An adhesive composition or an adhesive for use in medicine, and an adhesive composition or an adhesive for use in a method of preventing and / or treating a disease, such as a cardiological disease, a neurological disease, an oncological disease, a vascular disease, an immunological disease, a carcinoid, and / or an infectious disease, is also provided.

Description

[0001] ADHESIVE COMPOSITION COMPRISING AMYLOPECTIN AND MASTIC GUM

[0002] FIELD OF THE INVENTION

[0003] [1] The invention is based on an adhesive composition comprising amylopectin, mastic gum, and at least one solvent, such as water and / or an alcoholic solvent, for example ethanol, optionally further comprising glycerol and / or sodium chloride. The invention also pertains to an adhesive, obtainable from an adhesive composition according to this invention, wherein the adhesive is a conductive or a non- conductive adhesive. The invention also pertains to a method for preparing and / or obtaining an adhesive composition or an adhesive, and to an adhesive composition or an adhesive obtainable by the method according to this invention. An adhesive composition or an adhesive for use in medicine, and an adhesive composition or an adhesive for use in a method of preventing and / or treating a disease, such as a cardiological disease, a neurological disease, an oncological disease, a vascular disease, an immunological disease, a carcinoid, and / or an infectious disease, is also provided.

[0004] DESCRIPTION

[0005] [2] In the field of biosensing and wearable technology, the development of on-skin adhesives stands at the forefront of innovation, promising a transformative impact on various fields, including clinical diagnostics, therapeutics, and research. These adhesives play a role in securely affixing sensors directly onto the skin, facilitating the efficient and reliable recording of signals. In contrast, mobile integrated electrode systems utilize skin adhesive for secure placement, providing enhanced portability, comfort level, ease of use, and adaptability to diverse body shapes.

[0006] [3] To achieve this goal, it is crucial to develop skin adhesives that are biocompatible, provide strong and durable adhesion, and adapt to various skin conditions while being easily detachable. On skin adhesives are classified into three types - chemical, mechanical, and physical adhesives - based on their interfacial adhesion mechanisms. Previous studies on chemical adhesives suggest that a combination of hydrogen bonds and covalent bonds enables them to perform effectively on sweaty and oily skin while remaining relatively easy to remove.

[0007] [4] Importantly, skin adhesives with reliable and consistent conductivity can potentially overcome another limitation associated with wet electrodes. This limitation arises from the substantial decrease in conductivity and signal quality resulting from the evaporation of water in the conductive gel or paste applied to wet electrodes. This lack of long-term stable conductivity can be rectified by employing either dry electrodes or wet electrodes with an enhanced conductive gel, the latter generally demonstrating lower impedance.

[0008] [5] WO 2019 / 090350 A2 relates to peptides that form adhesive bonds, and their use in methods for producing hydrogels and / or adhesive materials.

[0009] [6] CN 115636960 A relates to a photo-crosslinking silk fibroin hemostatic adhesive and a preparation method thereof, and belongs to the field of biological materials and biomedical applications.

[0010] [7] CN 116019969 A relates to a biomedical bonding system based on barnacle Trx-Balcp 19k protein. [8] Thus, it is an object of the invention to provide an adhesive composition and / or an adhesive that is biocompatible, provides strong and / or durable adhesion, can adapt to various skin conditions, is easily detachable, and / or is characterized by a long-term stable conductivity. It is a further object of the invention to provide a skin adhesive that is characterized by allowing and / or assisting in secure placement, providing enhanced portability, comfort level, ease of use, and / or adaptability to diverse body shapes. It is also an object of the invention to provide a method for preparing and / or obtaining an adhesive composition or an adhesive having the above characteristics. It is a further object of the invention to provide an adhesive composition and an adhesive for use in medicine, and / or for use in a method of preventing and / or treating a disease, such as a cardiological disease, a neurological disease, an oncological disease, a vascular disease, an immunological disease, a carcinoid, and / or an infectious disease.

[0011] [9] To solve the above problems, the inventors developed a novel chemical skin adhesive composition comprising amylopectin and mastic gum, two biocompatible materials. The adhesion properties of amylopectin arise from the hydroxyl groups that can form hydrogen bonds with the human skin. However, in cases when skin become moist or sweaty, the water molecules disrupt the bonding. Therefore, it is crucial to incorporate an additional interaction, such as covalent bonds by combining amylopectin with mastic gum. Importantly, when mastic gum is dissolved in an alcoholic solvent and comes into contact with human skin, a range of interaction occurs including hydrogen bonding, amide bonding and Schiff’s base formation.

[0012] BRIEF DESCRIPTION OF THE INVENTION

[0013]

[0010] Generally, and by way of brief description, the main aspects of the present invention can be described as follows:

[0014]

[0011] In a first aspect, the invention pertains to an adhesive comprising amylopectin, mastic gum, and at least one solvent, such as water and / or an alcoholic solvent, for example ethanol, optionally further comprising glycerol and / or sodium chloride.

[0015]

[0012] In a second aspect, the invention pertains to an adhesive, obtainable from an adhesive composition according to the first aspect of this invention, wherein the adhesive is a conductive or a non-conductive adhesive.

[0016]

[0013] In a third aspect, the invention pertains to a method for preparing and / or obtaining an adhesive composition or an adhesive.

[0017]

[0014] In a fourth aspect, the invention pertains to an adhesive composition or an adhesive, obtainable by the method according to the third aspect of this invention.

[0018]

[0015] In a fifth aspect, the invention pertains to an adhesive composition or an adhesive for use in medicine.

[0019]

[0016] In a sixth aspect, the invention pertains to an adhesive composition or an adhesive for use in a method of preventing and / or treating a disease, such as a cardiological disease, a neurological disease, an oncological disease, a vascular disease, an immunological disease, a carcinoid, and / or an infectious disease.

[0017] In a seventh aspect, the invention relates to a kit comprising an adhesive composition or an adhesive according to this invention.

[0020]

[0018] In an eighth aspect, the invention relates to a method of placing an adhesive according to this invention on a biological substrate, such as on a part of a body of an animal or a human subject, for example on the head, the chest, the arm, the leg, and / or the back of an animal or a human subject.

[0021] DETAILED DESCRIPTION OF THE INVENTION

[0022]

[0019] In the following, the elements of the invention will be described. These elements are listed with specific embodiments, however, it should be understood that they may be combined in any manner and in any number to create additional embodiments. The variously described examples and preferred embodiments should not be construed to limit the present invention to only the explicitly described embodiments. This description should be understood to support and encompass embodiments which combine two or more of the explicitly described embodiments or which combine the one or more of the explicitly described embodiments with any number of the disclosed and / or preferred elements. Furthermore, any permutations and combinations of all described elements in this application should be considered disclosed by the description of the present application unless the context indicates otherwise.

[0023]

[0020] In the first aspect, the invention pertains to an adhesive composition comprising amylopectin, mastic gum, and at least one solvent, such as water and / or an alcoholic solvent, for example ethanol, optionally further comprising glycerol and / or sodium chloride.

[0024]

[0021] According to the present invention, the term “adhesive” shall refer to a non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation either entirely or to a certain percentage. The terms “adhesive” and “glue” can be used interchangeably, and are also known as cement, mucilage, or paste.

[0025]

[0022] According to the present invention, the term “adhesive composition” shall refer to a composition having adhesive properties. In general, an adhesive is obtainable form an adhesive composition according to this invention.

[0026]

[0023] According to the present invention, the term “mastic gum” or “mastic” refers to a resin obtained from the mastic tree (Pistacia lentiscus). “Mastic gum” or “mastic” is also known as “tears of Chios”, being traditionally produced on the island Chios, and, like other natural resins, is produced in "tears" or droplets. “Mastic” is excreted by the resin glands of certain trees and dries into pieces of brittle, translucent resin. When chewed, the resin softens and becomes a bright white and opaque gum. The flavor of mastic gum is bitter at first, but after some chewing, it releases a refreshing flavor similar to pine and cedar.

[0027]

[0024] In one embodiment, the mastic gum is chios mastic gum, such as chios mastiha, optionally wherein the quantity of at least one triterpene in the mastic gum is between 60 wt.% and 80 wt.%, preferably between 65 wt.% and 75 wt.%, more preferably around 70 wt.%.

[0028]

[0025] Chios mastic gum is a natural resin originating from the mastic tree, and it is cultivated for its culinary usage. However, mastic gum is known for its antimicrobial properties, anti-inflammatory attributes and its adhesive properties.

[0026] In one embodiment, the mastic gum is a hydrophobic mastic gum, and / or comprises hydrophobic mastic gum molecules.

[0029]

[0027] In one embodiment, the adhesive composition comprises amylopectin in form of an amylopectin solution and mastic gum in form of a mastic gum solution, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%, and wherein the mastic gum solution has a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, or wherein the adhesive composition comprises amylopectin in form of an amylopectin solution and mastic gum in form of a mastic gum-glycerol mixture, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%, and wherein the mastic gum-glycerol mixture comprises a mastic gum solution having a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, and wherein the ratio of the mastic gum ethanol solution to glycerol is around 6: 1, preferably around 5: 1, more preferably around 4: 1, even more preferably around 3: 1, even more preferably around 2: 1, and most preferably around 1: 1.

[0030]

[0028] For obtaining a solution comprising the mastic gum ethanol solution and glycerol in a ratio of 1: 1, a certain amount (such as 1 ml) of the mastic gum ethanol solution is mixed with an equal amount (such as 1 ml) of glycerol.

[0031]

[0029] In one embodiment, the ratio of the amylopectin solution to the mastic gum solution, or of the amylopectin solution to the mastic gum-glycerol mixture, is between 3 to 0.1 and 0.1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is around 2 to 1.

[0032]

[0030] The inventors carefully and systematically optimized the performance of adhesive compositions according to this invention based on, e.g., lap shear adhesion tests and microscopic observations by optimizing (i) the amylopectin-water mixture, (ii) the mastic gum -ethanol mixture, (iii) the ratio of glycerol to mastic-gum to avoid aggregation, and then (iv) mixing the highest adhesion strength of amylopectin- water and mastic gum-ethanol-glycerol mixture (see Figure 1). Importantly, the inventors also performed a time -dependent test of the mixture with the highest adhesive strength (Figure 2A). The inventors further evaluated the performance of adhesive obtainable by an optimized adhesive composition according to the present invention, considering factors such as water-washability, adhesion duration, and practical applications (Figure 2B, C).

[0033]

[0031] The inventors surprisingly found that an adhesive composition having excellent characteristics for a non-conductive adhesive according to this invention comprises 1 mL of an amylopectin-water mixture with a water content of 60 wt.%, and 0.5 mL of a mastic gum-ethanol-glycerol mixture. The latter is prepared by adding 0.2 mL of glycerol to 1 mL of a mastic gum -ethanol mixture with a mastic gum concentration of 200 mg / mL. This optimal non-conductive adhesive composition showed excellent lap shear adhesion strength at 88.65 ± 5.27 kPa, measured immediately after applying a pressure of 6.3 kPa to the adhesive sandwiched between two PI films for ten minutes. Additionally, this adhesive also displayed exceptional durability, maintaining adhesion strength at 218.42 ± 7.58 kPa even after one week. Moreover, practical performance evaluation on human skin revealed residue-free detachment using water and robust adhesion lasting over 24 hours, even on skin with sweat and oil.

[0034]

[0032] In one embodiment, the adhesive composition is for a non-conductive adhesive or a conductive adhesive.

[0035]

[0033] In one embodiment, the adhesive composition is for a non-conductive adhesive, wherein the adhesive composition does not comprise sodium chloride (NaCl). In one embodiment, the adhesive composition is for a conductive adhesive, wherein the adhesive composition comprises sodium chloride (NaCl). A conductive adhesive is particularly useful for clinical diagnostics, such as for Electroencephalography (EEG).

[0036]

[0034] According to this invention, the term “conductive” shall refer to the property and / or ability of conducting something, such as electricity and / or heat. The term "conductive" shall also refer to a substance that is able to conduct something, such as electricity and / or heat. According to this invention, a “conductor” refers to an object or type of material that allows the flow of charge (such as an electric current) in one or more directions. In some embodiments, the flow of negatively charged electrons generates electric current, positively charged holes, and / or positive or negative ions. In a preferred embodiment, the term “conductive” shall refer to the property of having a reliable and consistent conductivity.

[0037]

[0035] The term “non-conductive” shall refer to the absence of the property and / or ability of conducting something, such as electricity and / or heat. For example, a “non-conductive” material and / or a “non- conductive” composition does not have the property and / or ability of conducting something, such as electricity and / or heat.

[0038]

[0036] After the non-conductive skin adhesive composition underwent a systematic optimization process through lap shear adhesion tests and microscopic observations, the inventors introduced 1 M NaCl to the optimal non-conductive adhesive composition to make a conductive adhesive composition. The inventors conducted electrical impedance spectroscopy measurements overtime on both the conductive skin adhesive and a commercially available EEG conductive gel, enabling a comparative analysis between the two (Figure 3).

[0039]

[0037] In one embodiment, the adhesive composition is for a conductive adhesive, and the adhesive composition comprises sodium chloride (NaCl), wherein, preferably, the content of NaCl in the adhesive composition is around 40 mg / mL to 80 mg / mL, more preferably around 50 mg / mL to 70 mg / mL, even more preferably around 55 mg / mL to 65 mg / mL, and most preferably around 58,44 mg / mL.

[0040]

[0038] In one embodiment, the adhesive composition is for a conductive adhesive, and the adhesive composition comprises sodium chloride (NaCl), wherein NaCl has been added to the amylopectin solution prior mixing the amylopectin solution with the mastic gum solution or the mastic gum -glycerol mixture.

[0039] In one embodiment, the adhesive composition is for a conductive adhesive, and the adhesive composition comprises sodium chloride (NaCl), wherein NaCl has been added to the amylopectin solution prior mixing the amylopectin solution with the mastic gum solution or the mastic gum-glycerol mixture, and wherein the content of NaCl in the amylopectin solution is around 70 to 100 mg / mL, preferably around 75 to 95 mg / mL, more preferably around 80 to 90 mg / mL, and most preferably around 87,66 mg / mL.

[0041]

[0040] In one embodiment, the adhesive composition comprises glycerol, optionally wherein glycerol facilitates an encapsulation, such as a partial encapsulation, of at least one mastic gum molecule, and / or facilitates the formation of amphiphilic molecules, for example micelles, optionally wherein the micelles encapsulate the at least one mastic gum molecule.

[0042]

[0041] The inventors surprisingly found that the presence of glycerol in an adhesive composition according to the present invention can assist in obtaining a homogenous adhesive composition. Combining mastic gum with amylopectin can generate a promising adhesive composition. However, an amylopectin- water mixture is a hydrophilic mixture, and mastic gum exhibits hydrophobic properties. The inventors found that the addition of glycerol and ethanol to mastic gum enables the formation of micelles (amphiphilic molecules) which encapsulate the hydrophobic mastic gum molecules. Once enveloped by amphiphilic molecules, the hydrophilic heads engage with the water molecules enabling the interaction with other hydrophilic substances, such as the molecules in the amylopectin-water mixture.

[0043]

[0042] Moreover, the inventors surprisingly found that the impedance of an adhesive composition for a conductive adhesive consistently remained below 100 kQ, attributed to the moisture-retaining effect of glycerol, which prevents the evaporation of water.

[0044]

[0043] One embodiment relates to an adhesive composition comprising:

[0045] (i) amylopectin,

[0046] (ii) mastic gum, and

[0047] (iii) at least one solvent, such as water and / or an alcoholic solvent, for example ethanol,

[0048] (iv) optionally further comprising glycerol and / or sodium chloride.

[0049]

[0044] One embodiment relates to an adhesive composition comprising:

[0050] (i) amylopectin in form of an amylopectin solution, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%,

[0051] (ii) mastic gum in form of a mastic gum solution, wherein the mastic gum solution has a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, and

[0052] (iii) at least one solvent, such as water and / or an alcoholic solvent, for example ethanol,

[0053] (iv) optionally further comprising sodium chloride, wherein the ratio of the amylopectin solution to the mastic gum solution is between 3 to 0. 1 and 0. 1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is around 2 to 1.

[0045] One embodiment relates to an adhesive composition comprising:

[0054] (i) amylopectin in form of an amylopectin solution, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%,

[0055] (ii) mastic gum in form of a mastic gum-glycerol mixture, wherein the mastic gum-glycerol mixture comprises a mastic gum solution having a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, and wherein the ratio of the mastic gum ethanol solution to glycerol is around 6: 1, preferably around 5: 1, more preferably around 4: 1, even more preferably around 3: 1, even more preferably around 2: 1, and most preferably around 1: 1,

[0056] (iii) at least one solvent, such as water and / or an alcoholic solvent, for example ethanol,

[0057] (iv) optionally further comprising sodium chloride, wherein the ratio of the amylopectin solution to the mastic gum-glycerol mixture is between 3 to 0.1 and 0.1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is 2 to 1.

[0058]

[0046] One embodiment relates to an adhesive composition comprising:

[0059] (i) amylopectin in form of an amylopectin solution, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%,

[0060] (ii) mastic gum in form of a mastic gum solution, wherein the mastic gum solution has a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution,

[0061] (iii) at least one solvent, such as water and / or an alcoholic solvent, for example ethanol, and

[0062] (iv) sodium chloride, wherein, preferably, the content of NaCl in the adhesive composition is around 40 mg / mL to 80 mg / mL, more preferably around 50 mg / mL to 70 mg / mL, even more preferably around 55 mg / mL to 65 mg / mL, and most preferably around 58,44 mg / mL, wherein the ratio of the amylopectin solution to the mastic gum solution is between 3 to 0. 1 and 0. 1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is around 2 to 1.

[0063]

[0047] In this embodiment, the adhesive composition is for a conductive adhesive.

[0064]

[0048] One embodiment relates to an adhesive composition comprising:

[0065] (i) amylopectin in form of an amylopectin solution, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%,

[0066] (ii) mastic gum in form of a mastic gum-glycerol mixture, wherein the mastic gum-glycerol mixture comprises a mastic gum solution having a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, wherein the ratio of the mastic gum ethanol solution to glycerol is around 6: 1, preferably around 5: 1, more preferably around 4: 1, even more preferably around 3: 1, even more preferably around 2: 1, and most preferably around 1: 1,

[0067] (iii) at least one solvent, such as water and / or an alcoholic solvent, for example ethanol, and

[0068] (iv) sodium chloride, wherein, preferably, the content of NaCl in the adhesive composition is around 40 mg / mL to 80 mg / mL, more preferably around 50 mg / mL to 70 mg / mL, even more preferably around 55 mg / mL to 65 mg / mL, and most preferably around 58,44 mg / mL, wherein the ratio of the amylopectin solution to the mastic gum-glycerol mixture is between 3 to 0.1 and 0.1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is 2 to 1.

[0069]

[0049] In this embodiment, the adhesive composition is for a conductive adhesive.

[0070]

[0050] In a second aspect, the invention pertains to an adhesive, obtainable from an adhesive composition according to the first aspect of this invention.

[0071]

[0051] In one embodiment, the adhesive according to the second aspect of this invention is a conductive or a non-conductive adhesive.

[0072]

[0052] In one embodiment, the adhesive according to the second aspect is a biocompatible adhesive and / or a skin adhesive, such as an adhesive for on-skin applications, for example for biosensing, for wearable technology, and / or for clinical diagnostics, such as for Electroencephalography (EEG), and / or wherein the adhesive is a washable adhesive, such as an adhesive washable in water, and / or wherein the adhesive is detachable after use of the adhesive, such as is detachable from skin after use of the adhesive.

[0073]

[0053] The inventors developed novel adhesives, preferably skin adhesives, both non-conductive and conductive, that incorporate amylopectin, mastic gum, and at least one solvent, such as water and / or an alcoholic solvent. In a preferred embodiment, the non-conductive adhesives, such as non-conductive skin adhesives, incorporate amylopectin, mastic gum, water, ethanol, and glycerol. In another preferred embodiment, the conductive adhesives, such as conductive skin adhesives, incorporate amylopectin, mastic gum, water, ethanol, glycerol, and sodium chloride.

[0074]

[0054] It is an advantage of the present invention that the adhesives can adapt to various skin conditions, and yet are easily detachable, such as are residue-free detachable from skin by using water.

[0075]

[0055] In one embodiment, the adhesive according to the second aspect is for affixing and / or placing at least one sensor directly onto the skin, thereby, optionally, facilitating the recording of at least one signal by the at least one sensor.

[0076]

[0056] In a preferred embodiment, the adhesive is for securely affixing and / or securely placing at least one sensor directly onto the skin, thereby, optionally, facilitating the recording, such as the efficient and / or reliable recording, of at least one signal by the at least one sensor.

[0057] In one embodiment, the adhesive according to the second aspect has an adhesion strength of at least 15.00 kPa, preferably of at least 30.00 kPa, more preferably of at least 60.00 kPa, even more preferably of at least 80.00 kPa, and most preferably of at least 100.00 kPa, such as around 89 kPa when measured immediately after applying a pressure, such as a pressure of 6.3 kPa, to the adhesive for a certain period of time, such as for ten minutes, and / or around 225 kPa when measured after 24 hours after applying a pressure, such as a pressure of 6.3 kPa, to the adhesive for a certain period of time, such as for ten minutes, and / or around 218 kPa when measured after 1 week after applying a pressure, such as a pressure of 6.3 kPa, to the adhesive for a certain period of time, such as for ten minutes.

[0077]

[0058] The inventors surprisingly found that an ideal non-conductive adhesive showed an excellent lap shear adhesion strength at 88.65 ± 5.27 kPa, measured immediately after applying a pressure of 6.3 kPa to the adhesive sandwiched between two PI films for ten minutes. Additionally, this adhesive also displayed exceptional durability, maintaining adhesion strength at 218.42 ± 7.58 kPa even after one week. The inventors also surprisingly found that the adhesive has an adhesion strength of around 225 kPa when measured after 24 hours after applying a pressure (i.e. around 168 hours after applying a pressure), such as a pressure of 6.3 kPa, to the adhesive for a certain period of time, such as for ten minutes. The adhesives of the present invention are thus characterized by a remarkable adhesion duration.

[0078]

[0059] The inventors found that the adhesion strength experienced a decrease to 19.91 ± 2.71 kPa when NaCl was introduced to the solution for the adhesive, i.e. when a conductive adhesive of the present invention was prepared. The drop in the adhesion strength of the conductive adhesive to 19.91 ± 2.71 kPa is most likely due to ion interaction and disruption of bonds.

[0079]

[0060] However, within the typical EEG frequency range (1Hz to 40Hz), the impedance of the conductive adhesive initially matches that of the commercial EEG conductive gel.

[0080]

[0061] In one embodiment, the adhesive according to the second aspect is a conductive adhesive, and the impedance of the conductive adhesive is no more than 120 kQ, preferably no more than 110 kQ, even more preferably no more than 105 kQ, and most preferably no more than 100 kQ.

[0081]

[0062] The inventors surprisingly found that after being exposed to the ambient environment for 8 hours and for 24 hours, the conductive adhesive of this invention exhibits significantly lower impedance and more stable phase behavior compared to its commercial counterpart, i.e. enhanced impedance properties compared to the commercial conductive gel.

[0082]

[0063] In a third aspect, the invention pertains to a method for preparing and / or obtaining an adhesive composition or an adhesive, for example an adhesive composition according to the first aspect of this invention, or an adhesive according to the second aspect of this invention, the method comprising the steps of: a) Providing amylopectin, mastic gum, and a solvent, such as water and / or an alcoholic solvent, for example ethanol; optionally further providing glycerol and / or sodium chloride; b) Optionally, swelling of the amylopectin as provided in step a), for example by applying a heatmoisture treatment, to obtain a swollen amylopectin preparation; c) Preparing an amylopectin solution by dissolving the amylopectin as provided in step a), or the swollen amylopectin preparation as obtained in step b), in a solvent, such as water, to obtain an amylopectin solution, such as an amylopectin solution having a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of between 55 wt.% and 65 wt.%, and most preferably of around 60 wt.%; d) Optionally, adding NaCl to the amylopectin solution as obtained in step c) to obtain an amylopectin NaCl solution, further optionally wherein the content of NaCl in the amylopectin solution is around 70 to 100 mg / mL, preferably around 75 to 95 mg / mL, more preferably around 80 to 90 mg / mL, and most preferably around 87,66 mg / mL; e) Preparing a mastic gum solution by dissolving mastic gum in an alcoholic solvent, such as ethanol, to obtain a mastic gum solution, wherein the mastic gum solution has a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, or preparing a mastic gum-glycerol mixture by dissolving mastic gum in an alcoholic solvent, such as ethanol, and mixing the mastic gum solution with glycerol to obtain a mastic gumglycerol mixture, wherein the mastic gum-glycerol mixture comprises a mastic gum solution having a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, and wherein the ratio of the mastic gum ethanol solution to glycerol is around 6: 1, preferably around 5: 1, more preferably around 4: 1, even more preferably around 3: 1, even more preferably around 2: 1, and most preferably around 1: 1, and f) Mixing the amylopectin solution as obtained in step c) or the amylopectin NaCl solution as obtained in step d) with the mastic gum solution as obtained in step e), or mixing the amylopectin solution as obtained in step c) or the amylopectin NaCl solution as obtained in step d) with the mastic gum-glycerol mixture as obtained in step e), wherein, preferably, the ratio of the amylopectin solution to the mastic gum solution, or the ratio of the amylopectin solution to the mastic gum-glycerol mixture, is between 3 to 0.1 and 0.1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is around 2 to 1.

[0083]

[0064] In one embodiment in step e), a certain amount of a solution comprising the mastic gum ethanol solution and a certain amount of glycerol is mixed. For example, to obtain a solution comprising the mastic gum ethanol solution and glycerol in a ratio of 1: 1, a certain amount (such as 1 ml) of the mastic gum ethanol solution is mixed with an equal amount (such as 1 ml) of glycerol.

[0084]

[0065] In a fourth aspect, the invention pertains to an adhesive composition or an adhesive, obtainable by the method according to the third aspect of this invention.

[0085]

[0066] In a fifth aspect, the invention pertains to an adhesive composition or an adhesive for use in medicine, for example an adhesive composition according to the first or the fourth aspect of this invention, or an adhesive according to the second or the fourth aspect of this invention, for use in medicine.

[0067] In a sixth aspect, the invention pertains to an adhesive composition or an adhesive for use in a method of preventing and / or treating a disease, such as a cardiological disease, a neurological disease, an oncological disease, a vascular disease, an immunological disease, a carcinoid, and / or an infectious disease, for example an adhesive composition according to the first or the fourth aspect of this invention, or an adhesive according to the second or the fourth aspect of this invention, for use in a method of preventing and / or treating a disease, such as a cardiological disease, a neurological disease, an oncological disease, a vascular disease, an immunological disease, a carcinoid, and / or an infectious disease.

[0086]

[0068] A seventh aspect relates to a kit comprising an adhesive composition or an adhesive according to any aspect and / or embodiment of this invention, optionally further comprising a manual for use.

[0087]

[0069] An eighth aspect relates to a method of placing an adhesive according to any aspect and / or embodiment of this invention on a biological substrate, such as on a part of a body of an animal or a human subject, for example on the head, the chest, the arm, the leg, and / or the back of an animal or a human subject.

[0088]

[0070] The terms “of the [present] invention”, “in accordance with the invention”, “according to the invention” and the like, as used herein are intended to refer to all aspects and embodiments of the invention described and / or claimed herein.

[0089]

[0071] As used herein, the term “comprising” is to be construed as encompassing both “including” and “consisting of’, both meanings being specifically intended, and hence individually disclosed embodiments in accordance with the present invention. Where used herein, “and / or” is to be taken as specific disclosure of each of the two specified features or components with or without the other. For example, “A and / or B” is to be taken as specific disclosure of each of (i) A, (ii) B and (iii) A and B, just as if each is set out individually herein. In the context of the present invention, the terms “about” and “approximately” denote an interval of accuracy that the person skilled in the art will understand to still ensure the technical effect of the feature in question. The term typically indicates deviation from the indicated numerical value by ±20%, ±15%, ±10%, and for example ±5%. As will be appreciated by the person of ordinary skill, the specific such deviation for a numerical value for a given technical effect will depend on the nature of the technical effect. For example, a natural or biological technical effect may generally have a larger such deviation than one for a man-made or engineering technical effect. As will be appreciated by the person of ordinary skill, the specific such deviation for a numerical value for a given technical effect will depend on the nature of the technical effect. For example, a natural or biological technical effect may generally have a larger such deviation than one for a man-made or engineering technical effect. Where an indefinite or definite article is used when referring to a singular noun, e.g. "a", "an" or "the", this includes a plural of that noun unless something else is specifically stated.

[0090]

[0072] It is to be understood that application of the teachings of the present invention to a specific problem or environment, and the inclusion of variations of the present invention or additional features thereto (such as further aspects and embodiments), will be within the capabilities of one having ordinary skill in the art in light of the teachings contained herein.

[0091]

[0073] Unless context dictates otherwise, the descriptions and definitions of the features set out above are not limited to any particular aspect or embodiment of the invention and apply equally to all aspects and embodiments which are described.

[0092]

[0074] All references, patents, and publications cited herein are hereby incorporated by reference in their entirety.

[0093] BRIEF DESCRIPTION OF THE FIGURES

[0094]

[0075] The figures show:

[0095]

[0076] Figure 1 shows A. The adhesion strength of different amylopectin water ratios. B. The adhesion strength of different mastic gum in ethanol concentrations. C. The adhesion strength of different mastic gum-glycerol mixtures D. The adhesion strength of different adhesive compositions according to the present invention comprising different ratios of the amylopectin solution to the mastic gum solution, or of the amylopectin solution to the mastic gum -glycerol mixture.

[0096]

[0077] Figure 2 A. shows the adhesion strength of an adhesive composition according to one embodiment of the present invention. B. shows no discomfort after placement of an adhesive according to one embodiment of the present invention. C. shows the placement of a non-conductive adhesive according to one embodiment of the present invention on the forehead and behind the ear of a subject.

[0097]

[0078] Figure 3 shows a comparison of the impedance (Q) of a commercial conductive gel compared to a conductive adhesive according to one embodiment of this invention over time.

[0098]

[0079] Figure 4 shows microscopic images of adhesive compositions according to this invention. A. An adhesive composition according to one embodiment of this invention comprising a mastic gum-glycerol mixture (1: 1 ratio of mixture A and B), which is non-homogenous. B. An adhesive composition according to one embodiment of this invention comprising a mastic gum-glycerol mixture, wherein the ratio of the mastic gum ethanol solution (comprising a 1 : 1 ratio of mixture A and B) to glycerol is around 6: 1, which is homogenous.

[0099] EXAMPLES

[0100]

[0080] Certain aspects and embodiments of the invention will now be illustrated by way of example and with reference to the description, figures and tables set out herein. Such examples of the methods, uses and other aspects of the present invention are representative only, and should not be taken to limit the scope of the present invention to only such representative examples.

[0101]

[0081] The examples show:

[0102] Example 1: Preparing a non-conductive adhesive

[0103]

[0082] A non-conductive adhesive of the present invention is composed of two main materials: amylopectin and mastic gum.

[0104]

[0083] Amylopectin from maize, glycerol (> 99.5%), ethanol (> 99.8%) and sodium chloride (> 99.0%) were purchased from Sigma- Aldrich. Mastic gum, specifically natural mastiha from chios, was procured from Chios. A commercial mastic spirit glue was obtained from Kroylan GmbH, while an EEG conductive gel (ABRALYT HiCl) was purchased from Easycap GmbH.

[0105]

[0084] The amylopectin is a glucose polymer with a branching structure that exposes many hydroxyl groups. The hydroxyl groups contribute significantly to its adhesive property and the ability to form hydrogen bonding with surfaces. Dry amylopectin powder lacks adhesive properties and is insoluble in cold water. However, the swelling of amylopectin by applying a heat-moisture treatment can reveal more hydroxyl groups which form more hydrogen bonds with surfaces. The hydroxyl group can create hydrogen bonding with the amine groups, carboxylic acid groups, and thiol groups present on the surface of the skin.

[0106]

[0085] For preparing amylopectin-water mixtures, 15 g amylopectin was introduced into 80 mb distilled water, heated to 90 °C in a water bath and stirred with a magnetic bar for over 12 hours to gelatinize amylopectin and evaporate water, until the water content (mass fraction) reached 60 wt.%. The water content was determined by subtracting the weight of the dried mixture from that of the initial wet mixture, and dividing by the weight of the wet mixture, multiplying by 100%. to study the effect of water content on amylopectin adhesion, five amylopectin-water mixtures were prepared, each with different water contents by subsequently diluting the 60 wt.% solution with distilled water to create mixtures with water content levels of 65 wt.%, 70 wt.%, 75 wt.%, and 80 wt.%.

[0107]

[0086] It is noteworthy that the amylopectin-water mixture entered a "gelatinization state" when the water content was below 55 wt.%. However, all samples experiencing gelatinization were deemed unsuitable for adhesive application due to their challenging handling and poor spreading characteristics. As shown in figure 1 A, a decrease in adhesion strength was observed with the increasing amount of water content. This decrease can be attributed to the reduction of internal cohesion forces, and the reduction of interfacial adhesion forces resulting from the occupation of hydroxyl groups on amylopectin molecules by water molecules. Therefore, the 60 wt% amylopectin-water mixture, showed the highest adhesion strength, measuring 55.84±4.61 kPa (mixture A). However, when the skin becomes moist or sweaty, the water molecules disrupt the hydrogen bond adhesion to wet surfaces, resulting in detachment. Consequently, it is crucial to incorporate other forms of bonding such as covalent bonds.

[0108]

[0087] Mastic gum is a complex natural resin made of approximately 120 chemical compounds, out of which triterpenes make up for 70% of the resin total weight. Triterpenes exist in a variety of structures, some of have functional groups including carboxylic acid groups, hydroxyl groups, aldehyde groups, and carbonyl groups. As amylopectin, the mastic gum in its dry resin state lacks adhesiveness, but when dissolved in alcoholic solvents the adhesion property is enhanced and exposing the above-mentioned functional groups. When the dissolved mastic mixture becomes in contact with the human skin, a range of interactions occurs including hydrogen bonding, amide bonding and Schiff’s base interaction.

[0109]

[0088] To prepare mastic gum-ethanol mixtures, 2 g mastic gum was mixed with 1.5 mb ethanol using a mini shaker at a speed of 2000 rpm for 5 minutes. 10 pL of the supernatant was extracted and the weight of the residue after complete evaporation of ethanol was measured, indicating a mastic gum concentration of 650 mg / mL. To optimize the adhesion strength of mastic gum, five mastic gum-ethanol mixtures were investigated, each with different mastic gum concentration: 50 mg / mL, 200 mg / mL, 350 mg / mL, 500 mg / mL and 650 mg / mL. These mastic gum mixtures were prepared by diluting the supernatant as obtained after centrifugation at a speed of 2000 rpm for 5 minutes was then diluted using ethanol to create mixtures with mastic gum concentrations of 500 mg / mL, 350 mg / mL, 200 mg / mL and 50 mg / mL.

[0110]

[0089] Of note, a decline in adhesion strength with higher mastic gum concentrations was observed (see Figure IB). The decline in adhesion strength with higher mastic gum concentrations can be ascribed to the excess of ductile mastic gum. Conversely, the reduction in adhesion strength with lower mastic gum concentration can be attributed to insufficient bonding. As results, the 200 mg / mL mastic gum-ethanol concentration exhibited the highest adhesion strength in comparison to the other investigated mixture, measuring 33.10 ± 2.50 kPa (mixture B), as shown in Figure IB. However, the mastic gum adhesive cannot be washed away by water due to the hydrophobic property, rendering it use less convenient for short term on skin applications.

[0111]

[0090] To prepare a non-conductive adhesive, the amylopectin-water mixture (without sodium chloride) was added to 50 pL of mastic gum-ethanol mixture, and thoroughly stirred using a stick. This procedure was repeated until the added mastic gum-ethanol-glycerol mixture reached the desired volume.

[0112] Example 2: Preparing a non-conductive adhesive comprising glycerol

[0113]

[0091] Combining mastic gum with amylopectin holds the potential of developing and adhesive that can form multiple hydrogen bonding, covalent bonding, and can be washed away by water. However, amylopectin-water mixture is a hydrophilic mixture, and mastic gum exhibits hydrophobic properties. One solution is the formation of micelles (amphiphilic molecules) which encapsulate the hydrophobic molecules. Once enveloped by amphiphilic molecules, the hydrophilic heads engage with the water molecules enabling the interaction with other hydrophilic substances. Glycerol lacks amphiphilic properties. However, when glycerol and ethanol are combined through hydrogen bonding, the combination can exhibit amphiphilic properties. This allows for the partial encapsulation of the mastic gum molecules. Thus, mastic gum-ethanol-glycerol mixtures are prepared by adding 0.2 mL, 0.6 mL, or 1.0 mL of glycerol to 1 mL of the 200mg / mL mastic gum-ethanol mixture. These mixtures were subsequently blended using a mini shaker at a speed of 2000 rpm for 5 minutes.

[0114]

[0092] As shown in figure 1C, the adhesion strength experienced an increase with less glycerol content in the mixture. The decline in adhesion strength can be ascribed to both the decline in cohesive forces due to the rise micelles, and the decline in interfacial adhesion forces resulting from the reduction in mastic gum concentration. Among the mastic gum-ethanol-glycerol mixtures, the 0.2mL glycerol to 200mg / mL (mixture C) exhibited the highest adhesion strengths, measuring at 62.50±5.51 kPa as shown in figure 1C.

[0115]

[0093] Finally, to determine the optimal ratio between the mixture A and mixture C, four ratios were investigated 1: 1 , 2: 1 ,4: 1,1:2, (Mixture A : Mixture C), and an additional sample of 1: 1 ratio of mixture A with mixture B (without glycerol). Among the five investigated ratios, the 2: 1 ratio exhibited the highest adhesion strength at 88.65±5.27 kPa as shown in figure ID, and left the least residue on the polyimide substrate as shown in figure S 1. Moreover, the 1: 1 ratio of mixture A and B exhibited an adhesion strength at 71.05±6.89 kPa. However, as shown in figure 4A despite the high adhesion strength, the mixture was non-homogenous in comparison to the other mixture with glycerol as shown in figure 4B.

[0094] To prepare a non-conductive adhesive, the amylopectin-water mixture (without sodium chloride) was added to 50 pL of mastic gum-ethanol-glycerol mixture, and thoroughly stirred using a stick. This procedure was repeated until the added mastic gum-ethanol-glycerol mixture reached the desired volume.

[0116] Example 3: Examination of the adhesive strength of the adhesives of the present invention

[0117]

[0095] To examine the lap shear adhesion strength of the optimal non-conductive adhesive (2: 1 ratio of mixture A and C) overtime, measurements were conducted at various time intervals following exposure to ambient conditions (constant lab temperature and humidity): 1 hour, 8 hours, 24 hours, and 1 week.

[0118]

[0096] The adhesion performance of the adhesives was tested with a universal testing machine (TesT, Germany) using lap shear tests. 10 pL of the adhesive was sandwiched between two polyimide (PI) substrates (thickness 125 pm) to form a bonding area of 2 cm * 1 cm. A 6.3 kPa pressure was applied for 10 minutes to promote bonding. The lap shear rate was 5 mm / min. For each type of adhesive, five samples were measured.

[0119]

[0097] The adhesion strength continued to rise as time increased, surpassing 225 kPa after 24 hours and sustaining a robust adhesion strength of 218.42 ± 7.58 kPa even after 1 week, as illustrated in Figure 2A. It is worth mentioning that the universal testing machine has a force limitation of 45 N, corresponding to an adhesion strength of 225 kPa.

[0120] Example 4: Practical performance evaluation of the non-conductive adhesive of this invention

[0121]

[0098] To assess the practical performance of the optimal non-conductive adhesive for on-skin application, dry electroencephalography holders using thermoplastic polyurethane (TPU) were fabricated using a 3D fused deposition modelling (FDM) printer (Ultimaker, the Netherlands). Each electrode holder was designed with two threaded holes (diameter 5 mm) and a slim rectangular base (25 mm x 20 mm x 0.25 mm) at the bottom for contact with the adherend. Initially, one tough PLA and one TPU holder were affixed to the back of the hand using the optimal non-conductive adhesive, the adhesiveness and residue after water washing were observed. Following this, several PLA and TPU holders were applied to both the hairy forehead and hairless skin behind the ear as shown in figure 2C to assess durability while the pilot engaged in daily activities such as sports, showering (without direct water rinsing on the electrode holder) and sleeping. The pilot was instructed to promptly report any discomfort or skin irritation during this period.

[0122]

[0099] Regarding durability, the TPU holders stayed stably for over 24 hours on the sweaty and oily hairy forehead and the hairless skin behind the ear. The pilot underwent normal daily activities which include sport activities, showering (avoiding direct rinsing) and sleeping. Intentional detachment of TPU holders after 24 hours was effectively triggered through direct lukewarm water rinsing for approx. 2 minutes. No discomfort or skin irritation was reported by the pilot during this extended period as shown in figure 2B.

[0123] Example 5: Preparing a conductive adhesive

[0124]

[0100] A conductive adhesive with 1 M sodium chloride according to this invention was made by adding 175.32 mg sodium chloride to a 2 m of amylopectin-water mixture with 60 wt.% water, heated to 80 °C and stirred until no solid was visible. 2 m of this amylopectin-water NaCl mixture was combined with 1 m of mastic gum-ethanol-glycerol mixture. Compared to the optimal non-conductive adhesive, the adhesion strength of the conductive adhesive dropped to 19.91 ± 2.71 kPa due to ion interaction and disruption of bonds.

[0125]

[0101] The initial impedance of the conductive adhesive of this invention was comparable to that of the commercial conductive gel, with a smaller phase angle. The impedance of the commercial conductive gel was measured at 4.16 ± 0.69 kQ, while the impedance of the conductive adhesive of this invention was 5.47 ± 0.64 kQ at 10Hz as shown in figure 4. After 8 hours, a significant increase in impedance was observed in the commercial conductive gel due to water evaporation. In contrast, the impedance of the conductive adhesive of this invention consistently remained below 100 kQ, attributed to the moistureretaining effect of glycerol. At 10 Hz, the commercial conductive gel exhibited an impedance of 860.02 ± 235.16 kQ, contrasting with the adhesive's impedance of the conductive adhesive of this invention of 30.22 ± 13.33 kQ. Following a 24-hour period, the impedance of the commercial conductive gel rose to 9.51 ± 4.35 MQ at 10 Hz. In comparison, the conductive adhesive of this invention displayed an impedance of 138.48 ± 26.42 kQ at 10 Hz as shown in figure 3.

[0126]

[0102] To prepare a conductive adhesive, the amylopectin-water mixture (with sodium chloride) was added to 50 pL of mastic gum-ethanol-glycerol mixture, and thoroughly stirred using a stick. This procedure was repeated until the added mastic gum-ethanol-glycerol mixture reached the desired volume.

[0127] Example 6: Electrical impedance spectroscopy of a conductive adhesive according to this invention

[0128]

[0103] To compare the electrical impedance of the conductive adhesive of this invention and the commercial conductive gel, both were placed on the patterned Au electrodes and a cuboid-shaped mold (2 cm x 0.5 cm x 0.1 cm) was used to control the shape of the samples. An impedance analyzer (PalmSens, the Netherlands) was used to record the impedance using a two-electrode setup. For both the conductive adhesive of this invention and the commercial conductive gel, five samples were measured.

[0129]

[0104] The features disclosed in the foregoing description, in the claims and / or in the accompanying drawings may, both separately and in any combination thereof, be material for realizing the invention in diverse forms thereof.

Claims

Claims1. An adhesive composition comprising amylopectin, mastic gum, and at least one solvent, such as water and / or an alcoholic solvent, for example ethanol, optionally further comprising glycerol and / or sodium chloride.

2. The adhesive composition according to claim 1, wherein the mastic gum is chios mastic gum, such as chios mastiha, optionally wherein the quantity of at least one triterpene in the mastic gum is between 60 wt.% and 80 wt.%, preferably between 65 wt.% and 75 wt.%, more preferably around 70 wt.%.

3. The adhesive composition according to claim 1 or 2, wherein the adhesive composition comprises amylopectin in form of an amylopectin solution and mastic gum in form of a mastic gum solution, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%, and wherein the mastic gum solution has a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, or wherein the adhesive composition comprises amylopectin in form of an amylopectin solution and mastic gum in form of a mastic gum-glycerol mixture, wherein the amylopectin solution has a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of around 60 wt.%, and wherein the mastic gum-glycerol mixture comprises a mastic gum solution having a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, and wherein the ratio of the mastic gum solution to glycerol is around 6:1, preferably around 5:1, more preferably around 4:1, even more preferably around 3:1, even more preferably around 2:1, and most preferably around 1:1.

4. The adhesive composition according to claim 3, wherein the ratio of the amylopectin solution to the mastic gum solution, or of the amylopectin solution to the mastic gumglycerol mixture, is between 3 to 0.1 and 0.1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is around 2 to 1.

5. The adhesive composition according to any one of the preceding claims, wherein if the adhesive composition is for a conductive adhesive, the adhesive composition comprises sodium chloride (NaCl), wherein, preferably, the content of NaCl in the adhesive composition is around 40 mg / mL to 80 mg / mL, more preferably around 50 mg / mL to 70 mg / mL, even more preferably around 55 mg / mL to 65 mg / mL, and most preferably around 58,44 mg / mL.

6. The adhesive composition according to any one of the preceding claims, wherein the adhesive composition comprises glycerol, optionally wherein glycerol facilitates an encapsulation, such as a partial encapsulation, of at least one mastic gum molecule, and / or facilitates the formation of amphiphilic molecules, for example micelles, optionally wherein the micelles encapsulate the at least one mastic gum molecule.

7. An adhesive, obtainable from an adhesive composition according to any one of the preceding claims, wherein the adhesive is a conductive or a non-conductive adhesive.

8. The adhesive according to claim 7, wherein the adhesive is a biocompatible adhesive and / or a skin adhesive, such as an adhesive for on-skin applications, for example for biosensing, for wearable technology, and / or for clinical diagnostics, such as for Electroencephalography (EEG), and / or wherein the adhesive is a washable adhesive, such as an adhesive washable in water, and / or wherein the adhesive is detachable after use of the adhesive, such as is detachable from skin after use of the adhesive.

9. The adhesive according to claim 7 or 8, wherein the adhesive is for affixing and / or placing at least one sensor directly onto the skin, thereby, optionally, facilitating the recording of at least one signal by the at least one sensor.

10. The adhesive according to any one of claims 7 to 9, wherein the adhesive has an adhesion strength of at least 15.00 kPa, preferably of at least 30.00 kPa, more preferably of at least 60.00 kPa, even more preferably of at least 80.00 kPa, and most preferably of at least 100.00 kPa, such as around 89 kPa when measured immediately after applying a pressure, such as a pressure of 6.3 kPa, to the adhesive for a certain period of time, such as for ten minutes, and / or around 225 kPa when measured after 24 hours after applying a pressure, such as a pressure of 6.3 kPa, to the adhesive for a certain period of time, such as for ten minutes, and / or around 218 kPa when measured after 1 week after applying a pressure, such as a pressure of 6.3 kPa, to the adhesive for a certain period of time, such as for ten minutes.

11. The adhesive according to any one of claims 7 to 10, wherein if the adhesive is a conductive adhesive, the impedance of the conductive adhesive is no more than 120 kfl, preferably no more than 110 kfl, even more preferably no more than 105 kfl, and most preferably no more than 100 kfl.

12. A method for preparing and / or obtaining an adhesive composition or an adhesive, for example an adhesive composition according to any one of claims 1 to 6, or an adhesive according to any one of claims to 7 to 11, the method comprising the steps of:a) Providing amylopectin, mastic gum, and a solvent, such as water and / or an alcoholic solvent, for example ethanol; optionally further providing glycerol and / or sodium chloride; b) Optionally, swelling of the amylopectin as provided in step a), for example by applying a heat-moisture treatment, to obtain a swollen amylopectin preparation; c) Preparing an amylopectin solution by dissolving the amylopectin as provided in step a), or the swollen amylopectin preparation as obtained in step b), in a solvent, such as water, to obtain an amylopectin solution, such as an amylopectin solution having a water content of between 40 wt.% and 80 wt.%, preferably of between 50 wt.% and 70 wt.%, more preferably of between 55 wt.% and 65 wt.%, and most preferably of around 60 wt.%; d) Optionally, adding NaCl to the amylopectin solution as obtained in step c) to obtain an amylopectin NaCl solution, further optionally wherein the content of NaCl in the amylopectin solution is around 70 to too mg / mL, preferably around 75 to 95 mg / mL, more preferably around 80 to 90 mg / mL, and most preferably around 87,66 mg / mL; e) Preparing a mastic gum solution by dissolving mastic gum in an alcoholic solvent, such as ethanol, to obtain a mastic gum solution, wherein the mastic gum solution has a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, or preparing a mastic gum-glycerol mixture by dissolving mastic gum in an alcoholic solvent, such as ethanol, and mixing the mastic gum solution with glycerol to obtain a mastic gum-glycerol mixture, wherein the mastic gum-glycerol mixture comprises a mastic gum solution having a concentration of between 160 mg / mL and 240 mg / mL, preferably of between 180 mg / mL and 220 mg / mL, more preferably of around 200 mg / mL, such as a 200 mg / mL mastic gum ethanol solution, and wherein the ratio of the mastic gum solution to glycerol is around 6:1, preferably around 5:1, more preferably around 4:1, even more preferably around 3:1, even more preferably around 2:1, and most preferably around 1:1, and f) Mixing the amylopectin solution as obtained in step c) or the amylopectin NaCl solution as obtained in step d) with the mastic gum solution as obtained in step e), or mixing the amylopectin solution as obtained in step c) or the amylopectin NaCl solution as obtained in step d) with the mastic gum-glycerol mixture as obtained in step e), wherein, preferably, the ratio of the amylopectin solution to the mastic gum solution, or the ratio of the amylopectin solution to the mastic gum-glycerol mixture, is between 3 to 0.1 and 0.1 to 3, preferably is between 2.5 to 0.5 and 0.5 to 2.5, more preferably is between 2.2 to 0.8 and 0.8 to 2.2, and most preferably is around 2 to 1.

13. An adhesive composition or an adhesive, obtainable by the method according to claim14- An adhesive composition according to any one of claims 1 to 6, an adhesive composition according to claim 13, an adhesive according to any one of claims 7 to 11, or an adhesive according to claim 13, for use in medicine.

15. An adhesive composition according to any one of claims 1 to 6, an adhesive composition according to claim 13, an adhesive according to any one of claims 7 to 11, or an adhesive according to claim 13, for use in a method of preventing and / or treating a disease, such as a cardiological disease, a neurological disease, an oncological disease, a vascular disease, an immunological disease, a carcinoid, and / or an infectious disease.

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