using System;

using System.IO;

using System.Text;

using Newtonsoft.Json;

public class Program

{

    public static void Main()

    {

        ActivityEventNotification notification = new ActivityEventNotification() { Title = "\uD835" };

        byte[] bytes = SerializeToBytes(notification);

        Console.WriteLine(bytes.Length);

    }

        /// <summary>

        /// Serializes an <see cref="ActivityEventNotification" /> instance to a byte array.

        /// </summary>

        /// <param name="activityNotification">The instance.</param>

        /// <returns>A byte array serialized representation of the instance.</returns>

        public static byte[] SerializeToBytes(ActivityEventNotification activityNotification)

        {

            using (var stream = new MemoryStream())

            {

                using (JsonWriter writer = new JsonTextWriter(new StreamWriter(stream)))

                {

                    var serializer = JsonSerializer.CreateDefault(new JsonSerializerSettings());

                    serializer.Serialize(writer, activityNotification);

​

                    writer.Flush();

                    return stream.ToArray();

                }

            }

        }

}

public class ActivityEventNotification

{

    public string Title { get; set; }

}